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Structure (mathematical logic)

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43: 12073: 242: 2442: 9525:. Types are inductively defined; given two types δ and σ there is also a type σ → δ that represents functions from objects of type σ to objects of type δ. A structure for a typed language (in the ordinary first-order semantics) must include a separate set of objects of each type, and for a function type the structure must have complete information about the function represented by each object of that type. 9547:. When using full higher-order semantics, a structure need only have a universe for objects of type 0, and the T-schema is extended so that a quantifier over a higher-order type is satisfied by the model if and only if it is disquotationally true. When using first-order semantics, an additional sort is added for each higher-order type, as in the case of a many sorted first order language. 2095: 2224: 1908: 7046:
Structures are sometimes referred to as "first-order structures". This is misleading, as nothing in their definition ties them to any specific logic, and in fact they are suitable as semantic objects both for very restricted fragments of first-order logic such as that used in universal algebra, and
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Both universal algebra and model theory study classes of (structures or) algebras that are defined by a signature and a set of axioms. In the case of model theory these axioms have the form of first-order sentences. The formalism of universal algebra is much more restrictive; essentially it only
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on a database can be described by another structure in the same signature as the database model. A homomorphism from the relational model to the structure representing the query is the same thing as a solution to the query. This shows that the conjunctive query problem is also equivalent to the
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The set of integers gives an even smaller substructure of the real numbers which is not a field. Indeed, the integers are the substructure of the real numbers generated by the empty set, using this signature. The notion in abstract algebra that corresponds to a substructure of a field, in this
2437:{\displaystyle {\begin{alignedat}{3}\operatorname {ar} _{f}&(+)&&=2,\\\operatorname {ar} _{f}&(\times )&&=2,\\\operatorname {ar} _{f}&(-)&&=1,\\\operatorname {ar} _{f}&(0)&&=0,\\\operatorname {ar} _{f}&(1)&&=0.\\\end{alignedat}}} 9509:
0 × 0 = 1 is not true.) Therefore, one is naturally led to allow partial functions, i.e., functions that are defined only on a subset of their domain. However, there are several obvious ways to generalize notions such as substructure, homomorphism and identity.
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In the case of fields this strategy works only for addition. For multiplication it fails because 0 does not have a multiplicative inverse. An ad hoc attempt to deal with this would be to define 0 = 0. (This attempt fails, essentially because with this definition
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Many-sorted structures are often used as a convenient tool even when they could be avoided with a little effort. But they are rarely defined in a rigorous way, because it is straightforward and tedious (hence unrewarding) to carry out the generalization explicitly.
6681: 9391: 7849: 9497:). One consequence is that the choice of a signature is more significant in universal algebra than it is in model theory. For example, the class of groups, in the signature consisting of the binary function symbol × and the constant symbol 1, is an 2090:{\displaystyle {\begin{alignedat}{3}{\mathcal {Q}}&=(\mathbb {Q} ,\sigma _{f},I_{\mathcal {Q}})\\{\mathcal {R}}&=(\mathbb {R} ,\sigma _{f},I_{\mathcal {R}})\\{\mathcal {C}}&=(\mathbb {C} ,\sigma _{f},I_{\mathcal {C}})\\\end{alignedat}}} 8858:
also prescribe on which sorts the functions and relations of a many-sorted structure are defined. Therefore, the arities of function symbols or relation symbols must be more complicated objects such as tuples of sorts rather than natural numbers.
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together with two binary functions, that can be enhanced with a unary function, and two distinguished elements; but there is no requirement that it satisfy any of the field axioms. The
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to distinguish them from the "set models" discussed above. When the domain is a proper class, each function and relation symbol may also be represented by a proper class.
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is the same thing as a homomorphism between the two structures coding the graph. In the example of the previous section, even though the subgraph
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of two subsets is the closed subset generated by their union. Universal algebra studies the lattice of substructures of a structure in detail.
1195: 8865:, for example, can be regarded as two-sorted structures in the following way. The two-sorted signature of vector spaces consists of two sorts 9409: 2229: 1913: 11210: 10351: 6848:
As seen above, in the standard encoding of graphs as structures the induced substructures are precisely the induced subgraphs. However, a
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When a structure (and hence an interpretation function) is given by context, no notational distinction is made between a symbol
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that indicates how the signature is to be interpreted on the domain. To indicate that a structure has a particular signature
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Thus, for example, a "ring" is a structure for the language of rings that satisfies each of the ring axioms, and a model of
4504:. The rational numbers are the smallest substructure of the real (or complex) numbers that also satisfies the field axioms. 1447: 11537: 10860: 17: 6676:{\displaystyle (a_{1},a_{2},\dots ,a_{n})\in R^{\mathcal {A}}\iff (h(a_{1}),h(a_{2}),\dots ,h(a_{n}))\in R^{\mathcal {B}}} 511: 2782: 2711: 11542: 11532: 11269: 11122: 10475: 3821: 10466: 9386:{\displaystyle \times ^{\mathcal {V}}:|{\mathcal {V}}|_{S}\times |{\mathcal {V}}|_{V}\rightarrow |{\mathcal {V}}|_{V}} 4689:
are connected by an edge. In this encoding, the notion of induced substructure is more restrictive than the notion of
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because a logic over a type theory categorically corresponds to one ("total") category, capturing the logic, being
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The fact that such classes constitute a model of the traditional real number system was pointed out by Dedekind.
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is more common amongst set theorists, while the opposite convention is more common amongst model theorists.
7844:{\displaystyle (a_{1},\ldots ,a_{n})\in R\Leftrightarrow {\mathcal {M}}\vDash \varphi (a_{1},\ldots ,a_{n})} 11956: 11782: 11468: 11102: 10701: 4611: 4520: 3749: 1091: 12097: 11834: 11829: 11439: 11178: 11107: 10436: 10337: 9502: 7362: 7248: 4793: 605:
but often no notational distinction is made between a structure and its domain (that is, the same symbol
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allows first-order sentences that have the form of universally quantified equations between terms, e.g.
8463:{\displaystyle R=\{(a_{1},\ldots ,a_{n})\in M^{n}:{\mathcal {M}}\vDash \varphi (a_{1},\ldots ,a_{n})\}.} 7695:{\displaystyle R=\{(a_{1},\ldots ,a_{n})\in M^{n}:{\mathcal {M}}\vDash \varphi (a_{1},\ldots ,a_{n})\}.} 1765: 1633: 12112: 11763: 11353: 10747: 10715: 10406: 10185: 10160: 5857: 4051: 3380: 3132: 167: 9701: 8047: 6720: 6691: 5763: 5729: 5533: 5504: 4143: 4112: 3940: 2883: 2854: 2449: 547: 12053: 12002: 11899: 11397: 11358: 10835: 10480: 9739: 8794: 8599: 7337: 4369: 4297: 4133: 3527: 3294: 1420: 581: 10509: 9627:
Hodges, Wilfrid (2009). "Functional Modelling and Mathematical Models". In Meijers, Anthonie (ed.).
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From the model-theoretic point of view, structures are the objects used to define the semantics of
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Mapping of mathematical formulas to a particular meaning, in universal algebra and in model theory
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Thus an embedding is the same thing as a strong homomorphism which is one-to-one. The category σ-
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if it satisfies the defining axioms of that theory, although it is sometimes disambiguated as a
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and therefore structures for such a signature are not algebras, even though they are of course
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Some authors refer to structures as "algebras" when generalizing universal algebra to allow
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Jeavons, Peter; Cohen, David; Pearson, Justin (1998), "Constraints and universal algebra",
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respectively). Thus a structure (algebra) for this signature consists of a set of elements
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which is interpreted as that element. This relation is defined inductively using Tarski's
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A structure for this signature consists of a set of elements and an interpretation of the
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assigns functions and relations to the symbols of the signature. To each function symbol
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puts it: "A logic is always a logic over a type theory." This emphasis in turn leads to
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often contain only function symbols, a signature with no relation symbols is called an
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are part of the signature, and they play the role of names for the different domains.
12072: 12012: 11819: 11629: 11619: 11511: 11392: 11227: 11203: 10984: 10968: 10873: 10850: 10727: 10696: 10661: 10556: 10391: 10319: 10296: 10274: 10237: 10211: 10189: 10164: 10135: 10113: 10091: 10067: 10021: 9632: 9413: 9401: 8821: 7466: 7051:. In connection with first-order logic and model theory, structures are often called 7024: 5846: 4904: 638: 377: 178: 120: 112: 100: 10000: 7365:
is a structure in the language of set theory that satisfies each of the ZFC axioms.
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Every element of a structure is definable using the element itself as a parameter.
7016: 5214:{\displaystyle h(f(a_{1},a_{2},\dots ,a_{n}))=f(h(a_{1}),h(a_{2}),\dots ,h(a_{n}))} 4781: 2533:{\displaystyle I_{\mathcal {Q}}(+):\mathbb {Q} \times \mathbb {Q} \to \mathbb {Q} } 713: 707: 281: 226: 10153: 12007: 11997: 11951: 11934: 11889: 11851: 11753: 11673: 11480: 11407: 11380: 11368: 11274: 11188: 11162: 11117: 11085: 10886: 10688: 10631: 10581: 10546: 10504: 10233: 10207: 10087: 10086:, Graduate Texts in Mathematics, vol. 173 (3rd ed.), Berlin, New York: 10051: 9560: 9417: 7012: 4566:
The vertices of the graph form the domain of the structure, and for two vertices
4513: 4493: 4397: 1805: 1309: 218: 155: 11992: 11971: 11929: 11909: 11804: 11659: 11257: 11247: 11237: 11232: 11166: 11040: 10916: 10805: 10800: 10778: 10379: 10177: 10148: 8006:{\displaystyle {\mathcal {M}}\vDash \forall x(x=m\leftrightarrow \varphi (x)).} 7854:
An important special case is the definability of specific elements. An element
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is essentially the same thing as a relational structure. It turns out that a
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A Course in Model Theory: An Introduction to Contemporary Mathematical Logic
9505:. Universal algebra solves this problem by adding a unary function symbol . 9400:
In most mathematical endeavours, not much attention is paid to the sorts. A
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that is, if the following condition is satisfied: for every natural number
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where additional symbols can be derived, such as a unary function symbol
1256:{\displaystyle R^{\mathcal {A}}=I(R)\subseteq A^{\operatorname {ar(R)} }} 6836:. In this case induced substructures also correspond to subobjects in σ- 3057:
The ordinary signature for set theory includes a single binary relation
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The strong homomorphisms give rise to a subcategory of the category σ-
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Conversely, the domain of an induced substructure is a closed subset.
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The domain of a structure is an arbitrary set; it is also called the
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be a graph consisting of two vertices connected by an edge, and let
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The closed subsets (or induced substructures) of a structure form a
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Oxford English Dictionary, s.v. "model, n., sense I.8.b", July 2023
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the interpretations of all function and relation symbols agree on
2965:-structure in the same way. In fact, there is no requirement that 11639: 10431: 4509: 2935: 946: 9631:. Handbook of the Philosophy of Science. Vol. 9. Elsevier. 3258:{\displaystyle \sigma ({\mathcal {A}})=\sigma ({\mathcal {B}});} 2653:{\displaystyle I_{\mathcal {Q}}(-):\mathbb {Q} \to \mathbb {Q} } 10104:
Ebbinghaus, Heinz-Dieter; Flum, Jörg; Thomas, Wolfgang (1994),
8824:, every implicitly definable relation is explicitly definable. 9276:{\displaystyle 0_{S}^{\mathcal {V}}=0\in |{\mathcal {V}}|_{S}} 9209:{\displaystyle 0_{V}^{\mathcal {V}}=0\in |{\mathcal {V}}|_{V}} 6230:{\displaystyle (a_{1},a_{2},\dots ,a_{n})\in R^{\mathcal {A}}} 6071:{\displaystyle (b_{1},b_{2},\dots ,b_{n})\in R^{\mathcal {B}}} 4959:{\displaystyle h:|{\mathcal {A}}|\rightarrow |{\mathcal {B}}|} 11183: 10529: 10374: 9685:
A logical system that allows the empty domain is known as an
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be again the standard signature for fields. When regarded as
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when one discusses the notion in the more general setting of
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that preserves the functions and relations. More precisely:
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For a given theory in model theory, a structure is called a
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over another ("base") category, capturing the type theory.
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be the graph consisting of the same vertices but no edges.
3367:{\displaystyle |{\mathcal {A}}|\subseteq |{\mathcal {B}}|;} 3103: 2151:{\displaystyle \sigma _{f}=(S_{f},\operatorname {ar} _{f})} 2099:
In all three cases we have the standard signature given by
757:{\displaystyle \operatorname {ar} :\ S\to \mathbb {N} _{0}} 6985:{\displaystyle h:{\mathcal {A}}\rightarrow {\mathcal {B}}} 6416:{\displaystyle h:{\mathcal {A}}\rightarrow {\mathcal {B}}} 5896:{\displaystyle h:{\mathcal {A}}\rightarrow {\mathcal {B}}} 5715:{\displaystyle h:{\mathcal {A}}\rightarrow {\mathcal {B}}} 9521:, there are many sorts of variables, each of which has a 5856:
which has σ-structures as objects and σ-homomorphisms as
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can be identified with a constant element of the domain.
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Universal algebra studies structures that generalize the
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instead of a set. These structures are sometimes called
3447:{\displaystyle {\mathcal {A}}\subseteq {\mathcal {B}}.} 6952:
of a finite relational signature, find a homomorphism
1484:{\displaystyle f:{\mathcal {A}}^{2}\to {\mathcal {A}}} 955:. A structure with such a signature is also called an 162:
has a different scope that encompasses more arbitrary
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that corresponds to induced substructures is that of
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As a consequence of these conventions, the notation
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in the extended language containing the language of
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together with a constant symbol for each element of
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refers to the interpretation of the relation symbol
959:; this should not be confused with the notion of an 537:{\displaystyle \operatorname {dom} ({\mathcal {A}})} 10043: 9978: 7031: 2818:{\displaystyle I_{\mathcal {Q}}(1)\in \mathbb {Q} } 2747:{\displaystyle I_{\mathcal {Q}}(0)\in \mathbb {Q} } 10225: 10152: 10105: 9962: 9933: 9906: 9886: 9852: 9822: 9800: 9755: 9724: 9470: 9446: 9385: 9275: 9208: 9141: 9094: 9047: 8873:(for scalars) and the following function symbols: 8810: 8779: 8759: 8726: 8702: 8682: 8659: 8635: 8615: 8588: 8568: 8548: 8528: 8504: 8484: 8462: 8331: 8276: 8252: 8232: 8212: 8161: 8138: 8118: 8094: 8070: 8032: 8005: 7939: 7910: 7886: 7866: 7843: 7734: 7714: 7694: 7563: 7507: 7481: 7449: 7425: 7405: 7385: 7353: 7326: 7306: 7286: 7262: 7235: 7204: 7181: 7157: 7136: 7103: 6984: 6944: 6920: 6790: 6766: 6738: 6709: 6675: 6494: 6415: 6360: 6229: 6149: 6070: 5990: 5895: 5834: 5810: 5786: 5752: 5714: 5674: 5650: 5619: 5595: 5571: 5551: 5522: 5488: 5307: 5213: 5049: 4958: 4895: 4871: 4843: 4819: 4768: 4745: 4725: 4705: 4681: 4661: 4641: 4601: 4578: 4558: 4535: 4500:, and the real numbers form a substructure of the 4484: 4464: 4385: 4358: 4338: 4313: 4286: 4243: 4217: 4166: 4124: 4101: 4066: 4040: 4013: 3986: 3963: 3929: 3887: 3811: 3788: 3738: 3718: 3698: 3630: 3606: 3586: 3566: 3543: 3512: 3488: 3446: 3406: 3366: 3310: 3283: 3257: 3202: 3178: 3151: 3123: 3092: 3072: 3042: 3017: 2988: 2957: 2926: 2901: 2872: 2840: 2817: 2769: 2746: 2698: 2672: 2652: 2596: 2532: 2467: 2436: 2213: 2150: 2089: 1897: 1877: 1849: 1824: 1796: 1776: 1754: 1732: 1710: 1688: 1666: 1644: 1622: 1596: 1562: 1483: 1436: 1409: 1389: 1357: 1334: 1299: 1279: 1255: 1184: 1164: 1144: 1124: 1078: 1057: 1037: 1017: 993: 935: 908: 884: 864: 820: 776: 756: 697: 673: 621: 597: 570: 536: 457: 437: 417: 394: 368: 340: 10044:Burris, Stanley N.; Sankappanavar, H. P. (1981), 9981:Annals of Mathematics and Artificial Intelligence 9771: 9769: 9629:Philosophy of technology and engineering sciences 9512: 8832:Structures as defined above are sometimes called 4630: 3888:{\displaystyle f(b_{1},b_{2},\dots ,b_{n})\in B.} 3100:relation as a binary relation on these elements. 12089: 4346:assigns to every symbol of σ the restriction to 4102:{\displaystyle \langle B\rangle _{\mathcal {A}}} 2660:is the function that takes each rational number 272:In the context of mathematical logic, the term " 8015: 7722:is definable if and only if there is a formula 6805:of σ-structures and σ-embeddings is a concrete 4787: 4776:but not an induced substructure. The notion in 674:{\displaystyle \sigma =(S,\operatorname {ar} )} 284:(1831 – 1916), a pioneer in the development of 276:" was first applied in 1940 by the philosopher 9766: 9539:There is more than one possible semantics for 8760:{\displaystyle {\mathcal {M}}\vDash \varphi ,} 8284:is explicitly definable if there is a formula 7165:in the language consisting of the language of 4543:consisting of a single binary relation symbol 3699:{\displaystyle b_{1},b_{2},\dots ,b_{n}\in B,} 629:refers both to the structure and its domain.) 206:. Logicians sometimes refer to structures as " 10345: 8332:{\displaystyle \varphi (x_{1},\ldots ,x_{n})} 7564:{\displaystyle \varphi (x_{1},\ldots ,x_{n})} 5559:is the interpretation of the relation symbol 10255:A Concise Introduction to Mathematical Logic 10057: 8454: 8352: 7686: 7584: 7104:{\displaystyle {\mathcal {M}}=(M,\sigma ,I)} 4794:Universal algebra § Basic constructions 4459: 4429: 4218:{\displaystyle {\mathcal {A}}=(A,\sigma ,I)} 4119: 4116: 4088: 4081: 4061: 4055: 3003:needs an additional binary relation such as 2208: 2178: 341:{\displaystyle {\mathcal {A}}=(A,\sigma ,I)} 4465:{\displaystyle \sigma =\{+,\times ,-,0,1\}} 3930:{\displaystyle B\subseteq |{\mathcal {A}}|} 3489:{\displaystyle B\subseteq |{\mathcal {A}}|} 10537: 10352: 10338: 10249: 9801:{\displaystyle \mathbf {0} ,\mathbf {1} ,} 9763:In practice this never leads to confusion. 8841:to distinguish them from the more general 7137:{\displaystyle {\mathcal {M}}\vDash \phi } 6860:is not induced, the identity map id:  6582: 6578: 5395: 5391: 4404:of two subsets is their intersection. The 966: 10286: 9953: 9914:on the right refer to natural numbers of 9528: 9031:, the corresponding two-sorted structure 8827: 8184:. Broadly speaking, the convention that 7151: 6992:or show that no such homomorphism exists. 6868:is a homomorphism. This map is in fact a 6322: 6315: 6279: 3039: 3032: 3014: 3010: 2920: 2811: 2740: 2646: 2638: 2590: 2582: 2574: 2526: 2518: 2510: 2214:{\displaystyle S_{f}=\{+,\times ,-,0,1\}} 2048: 1991: 1934: 1885:like any other field, can be regarded as 1868: 1843: 1815: 1273: 821:{\displaystyle n=\operatorname {ar} (s).} 744: 87:Learn how and when to remove this message 9423: 8195: 7058: 6750:of the object theory σ in the structure 6495:{\displaystyle a_{1},a_{2},\dots ,a_{n}} 3417:The usual notation for this relation is 3104:Induced substructures and closed subsets 1608:consists of two binary function symbols 865:{\displaystyle n=\operatorname {ar} (s)} 50:This article includes a list of general 10079: 6891: 3524:if it is closed under the functions of 3054:in the usual, loose sense of the word. 487:(especially in universal algebra), its 14: 12090: 10359: 10223: 10201: 10176: 10147: 10125: 10013: 9626: 9596: – Additional mathematical object 9142:{\displaystyle |{\mathcal {V}}|_{S}=F} 9095:{\displaystyle |{\mathcal {V}}|_{V}=V} 7368: 6896:The following problem is known as the 6888:which is not an induced substructure. 5919:of the object theory and any elements 5579:of the object theory in the structure 2604:is multiplication of rational numbers, 10333: 9670: 7038:Model theory § First-order logic 4642:{\displaystyle (a,b)\!\in {\text{E}}} 3937:there is a smallest closed subset of 3789:{\displaystyle b_{1}b_{2}\dots b_{n}} 1125:{\displaystyle f^{\mathcal {A}}=I(f)} 10112:(2nd ed.), New York: Springer, 7004:can be studied using the methods of 6824:. If σ has only function symbols, σ- 6816:Induced substructures correspond to 5722:, although technically the function 4492:-structures in the natural way, the 1132:on the domain. Each relation symbol 236: 36: 10324:Stanford Encyclopedia of Philosophy 9428: 945:Since the signatures that arise in 24: 10128:Fundamentals of Mathematical Logic 9745: 9712: 9551:Structures that are proper classes 9465: 9441: 9366: 9339: 9312: 9296: 9256: 9234: 9189: 9167: 9116: 9069: 9040: 8800: 8743: 8719: 8652: 8605: 8521: 8408: 8269: 8111: 8058: 7964: 7956: 7918:if and only if there is a formula 7903: 7795: 7640: 7502: 7476: 7442: 7343: 7279: 7228: 7174: 7123: 7072: 6977: 6967: 6937: 6913: 6783: 6759: 6730: 6701: 6667: 6572: 6502:, the following equivalence holds: 6408: 6398: 6221: 6137: 6062: 5978: 5888: 5878: 5827: 5803: 5774: 5740: 5707: 5697: 5667: 5643: 5612: 5588: 5543: 5514: 5480: 5385: 5315:, the following implication holds: 5295: 5037: 4946: 4926: 4888: 4864: 4836: 4812: 4375: 4303: 4186: 4154: 4093: 3951: 3917: 3623: 3533: 3505: 3476: 3436: 3426: 3391: 3351: 3331: 3300: 3276: 3244: 3225: 3195: 3171: 3144: 3116: 2938:, which is not a field, is also a 2893: 2864: 2792: 2721: 2619: 2555: 2491: 2459: 2074: 2032: 2017: 1975: 1960: 1918: 1777:{\displaystyle \mathbf {\times } } 1645:{\displaystyle \mathbf {\times } } 1547: 1520: 1504: 1476: 1460: 1426: 1244: 1238: 1235: 1205: 1101: 1010: 614: 587: 558: 526: 309: 280:, in a reference to mathematician 56:it lacks sufficient corresponding 25: 12124: 10309: 10017:Categorical Logic and Type Theory 9732:may also be used to refer to the 9543:, as discussed in the article on 7516:cf. below) if there is a formula 5845:For every signature σ there is a 4519:The most obvious way to define a 4067:{\displaystyle \langle B\rangle } 3407:{\displaystyle |{\mathcal {A}}|.} 491:(especially in model theory, cf. 12071: 9816: 9791: 9783: 9725:{\displaystyle |{\mathcal {A}}|} 8071:{\displaystyle |{\mathcal {M}}|} 7042:Model theory § Definability 7032:Structures and first-order logic 6739:{\displaystyle R^{\mathcal {B}}} 6710:{\displaystyle R^{\mathcal {A}}} 5787:{\displaystyle |{\mathcal {B}}|} 5753:{\displaystyle |{\mathcal {A}}|} 5552:{\displaystyle R^{\mathcal {B}}} 5523:{\displaystyle R^{\mathcal {A}}} 4798: 4523:is a structure with a signature 4167:{\displaystyle |{\mathcal {A}}|} 4125:{\displaystyle \langle \rangle } 3964:{\displaystyle |{\mathcal {A}}|} 2902:{\displaystyle I_{\mathcal {C}}} 2873:{\displaystyle I_{\mathcal {R}}} 2540:is addition of rational numbers, 2468:{\displaystyle I_{\mathcal {Q}}} 1748: 1726: 1704: 1682: 1660: 1616: 571:{\displaystyle |{\mathcal {A}}|} 240: 41: 10263:Springer Science+Business Media 9756:{\displaystyle {\mathcal {A}}.} 9027:is a vector space over a field 8811:{\displaystyle {\mathcal {M}}.} 8616:{\displaystyle {\mathcal {M}}.} 7495:definable with parameters from 7354:{\displaystyle {\mathcal {M}}.} 7294:is the same as the language of 6998:constraint satisfaction problem 5057:, the following equation holds: 4386:{\displaystyle {\mathcal {A}}.} 4314:{\displaystyle {\mathcal {A}},} 3994:It is called the closed subset 3544:{\displaystyle {\mathcal {A}},} 3311:{\displaystyle {\mathcal {B}}:} 1905:-structures in an obvious way: 1696:) and the two constant symbols 1437:{\displaystyle {\mathcal {A}},} 1417:is a binary function symbol of 598:{\displaystyle {\mathcal {A}},} 10007: 9972: 9830:on the left refer to signs of 9718: 9706: 9692: 9679: 9664: 9645: 9620: 9607: 9513:Structures for typed languages 9373: 9360: 9356: 9346: 9333: 9319: 9306: 9263: 9250: 9196: 9183: 9123: 9110: 9076: 9063: 9055:consists of the vector domain 9048:{\displaystyle {\mathcal {V}}} 8727:{\displaystyle {\mathcal {M}}} 8660:{\displaystyle {\mathcal {M}}} 8529:{\displaystyle {\mathcal {M}}} 8512:must be over the signature of 8451: 8419: 8387: 8355: 8326: 8294: 8277:{\displaystyle {\mathcal {M}}} 8119:{\displaystyle {\mathcal {M}}} 8064: 8052: 7997: 7994: 7988: 7982: 7970: 7934: 7928: 7911:{\displaystyle {\mathcal {M}}} 7838: 7806: 7790: 7781: 7749: 7683: 7651: 7619: 7587: 7558: 7526: 7450:{\displaystyle {\mathcal {M}}} 7413:on the universe (i.e. domain) 7287:{\displaystyle {\mathcal {M}}} 7236:{\displaystyle {\mathcal {M}}} 7182:{\displaystyle {\mathcal {M}}} 7098: 7080: 6972: 6945:{\displaystyle {\mathcal {B}}} 6921:{\displaystyle {\mathcal {A}}} 6791:{\displaystyle {\mathcal {B}}} 6767:{\displaystyle {\mathcal {A}}} 6655: 6652: 6639: 6624: 6611: 6602: 6589: 6583: 6579: 6560: 6515: 6403: 6352: 6339: 6309: 6296: 6273: 6260: 6209: 6164: 6143: 6131: 6050: 6005: 5984: 5972: 5883: 5835:{\displaystyle {\mathcal {B}}} 5811:{\displaystyle {\mathcal {A}}} 5780: 5768: 5746: 5734: 5702: 5675:{\displaystyle {\mathcal {B}}} 5651:{\displaystyle {\mathcal {A}}} 5620:{\displaystyle {\mathcal {B}}} 5596:{\displaystyle {\mathcal {A}}} 5468: 5465: 5452: 5437: 5424: 5415: 5402: 5396: 5392: 5373: 5328: 5301: 5289: 5208: 5205: 5192: 5177: 5164: 5155: 5142: 5136: 5127: 5124: 5079: 5073: 5043: 5031: 4952: 4940: 4936: 4932: 4920: 4896:{\displaystyle {\mathcal {B}}} 4872:{\displaystyle {\mathcal {A}}} 4844:{\displaystyle {\mathcal {B}}} 4820:{\displaystyle {\mathcal {A}}} 4627: 4615: 4294:is an induced substructure of 4287:{\displaystyle (B,\sigma ,I')} 4281: 4258: 4212: 4194: 4160: 4148: 3957: 3945: 3923: 3911: 3873: 3828: 3631:{\displaystyle {\mathcal {A}}} 3513:{\displaystyle {\mathcal {A}}} 3482: 3470: 3397: 3385: 3357: 3345: 3337: 3325: 3291:is contained in the domain of 3284:{\displaystyle {\mathcal {A}}} 3249: 3239: 3230: 3220: 3203:{\displaystyle {\mathcal {B}}} 3179:{\displaystyle {\mathcal {A}}} 3152:{\displaystyle {\mathcal {B}}} 3124:{\displaystyle {\mathcal {A}}} 2969:of the field axioms hold in a 2804: 2798: 2733: 2727: 2642: 2631: 2625: 2586: 2567: 2561: 2522: 2503: 2497: 2416: 2410: 2375: 2369: 2334: 2328: 2293: 2287: 2252: 2246: 2145: 2119: 2080: 2044: 2023: 1987: 1966: 1930: 1553: 1541: 1537: 1527: 1514: 1471: 1381: 1375: 1329: 1323: 1247: 1241: 1223: 1217: 1119: 1113: 1018:{\displaystyle {\mathcal {A}}} 859: 853: 812: 806: 739: 668: 656: 622:{\displaystyle {\mathcal {A}}} 564: 552: 531: 521: 335: 317: 13: 1: 12032:History of mathematical logic 10204:Model Theory: An Introduction 10047:A Course in Universal Algebra 10037: 9963:{\displaystyle \mathbb {Q} .} 9404:however naturally leads to a 6378: 4411: 3496:of the domain of a structure 1878:{\displaystyle \mathbb {C} ,} 1825:{\displaystyle \mathbb {Q} ,} 1313:, because its interpretation 764:that ascribes to each symbol 291: 212:interpretation (model theory) 170:structures such as models of 11957:Primitive recursive function 10289:Introduction to Model Theory 9823:{\displaystyle \mathbf {-} } 9671:Quine, Willard V.O. (1940). 8190:definable without parameters 8178:definable without parameters 8016:Definability with parameters 6904:Given two finite structures 4788:Homomorphisms and embeddings 4244:{\displaystyle B\subseteq A} 2927:{\displaystyle \mathbb {Z} } 2446:The interpretation function 1850:{\displaystyle \mathbb {R} } 1755:{\displaystyle \mathbf {+} } 1733:{\displaystyle \mathbf {1} } 1711:{\displaystyle \mathbf {0} } 1689:{\displaystyle \mathbf {+} } 1667:{\displaystyle \mathbf {-} } 1623:{\displaystyle \mathbf {+} } 681:of a structure consists of: 632: 7: 10287:Rothmaler, Philipp (2000), 10080:Diestel, Reinhard (2005) , 9941:and to the unary operation 9655:. Oxford University Press. 9587: 9283:, or scalar multiplication 8596:is not in the signature of 8180:, while other authors mean 7940:{\displaystyle \varphi (x)} 7063:Each first-order structure 6850:homomorphism between graphs 4851:of the same signature σ, a 4496:form a substructure of the 2989:{\displaystyle \sigma _{f}} 2958:{\displaystyle \sigma _{f}} 1597:{\displaystyle \sigma _{f}} 1572: 971:Not to be confused with an 300:can be defined as a triple 115:along with a collection of 10: 12129: 11021:Schröder–Bernstein theorem 10748:Monadic predicate calculus 10407:Foundations of mathematics 10186:Cambridge University Press 10161:Cambridge University Press 10020:, Elsevier, pp. 1–4, 9532: 8877: 8492:used to define a relation 8200:Recall from above that an 7508:{\displaystyle \emptyset } 7482:{\displaystyle \emptyset } 7035: 7011:Another application is in 6843: 4791: 3043:{\displaystyle \,\leq ,\,} 1263:on the domain. A nullary ( 970: 636: 578:is used for the domain of 472: 232: 150:is used for structures of 29: 12067: 12054:Philosophy of mathematics 12003:Automated theorem proving 11985: 11880: 11712: 11605: 11457: 11174: 11150: 11128:Von Neumann–Bernays–Gödel 11073: 10967: 10871: 10769: 10760: 10687: 10622: 10528: 10450: 10367: 10271:10.1007/978-1-4419-1221-3 8182:definable with parameters 8162:{\displaystyle \varphi .} 8042:definable with parameters 7144:defined for all formulas 4366:of its interpretation in 4251:is a closed subset, then 4134:finitary closure operator 973:interpretation of a model 920:of the interpretation of 468: 445:one can refer to it as a 9600: 9471:{\displaystyle \forall } 9447:{\displaystyle \forall } 8710:is the only relation on 8636:{\displaystyle \varphi } 8549:{\displaystyle \varphi } 8485:{\displaystyle \varphi } 8095:{\displaystyle \varphi } 8082:) if there is a formula 7735:{\displaystyle \varphi } 6375:that was defined above. 5682:is typically denoted as 4512:, rather than that of a 4508:signature, is that of a 3210:have the same signature 3018:{\displaystyle \,<\,} 1740:(uniquely determined by 1674:(uniquely determined by 395:{\displaystyle \sigma ,} 183:Tarski's theory of truth 123:that are defined on it. 30:Not to be confused with 12103:Mathematical structures 11704:Self-verifying theories 11525:Tarski's axiomatization 10476:Tarski's undefinability 10471:incompleteness theorems 9993:10.1023/A:1018941030227 9675:. Vol. vi. Norton. 7158:{\displaystyle \,\phi } 5726:is between the domains 4536:{\displaystyle \sigma } 4485:{\displaystyle \sigma } 3796:is again an element of 3706:the result of applying 2909:are similarly defined. 1898:{\displaystyle \sigma } 1577:The standard signature 1365:and its interpretation 980:interpretation function 967:Interpretation function 508:Sometimes the notation 458:{\displaystyle \sigma } 438:{\displaystyle \sigma } 404:interpretation function 278:Willard Van Orman Quine 71:more precise citations. 12078:Mathematics portal 11689:Proof of impossibility 11337:propositional variable 10647:Propositional calculus 10224:Poizat, Bruno (2000), 10202:Marker, David (2002), 10182:A shorter model theory 9964: 9935: 9908: 9888: 9887:{\displaystyle 0,1,2,} 9854: 9853:{\displaystyle S_{f}.} 9824: 9802: 9757: 9726: 9594:Mathematical structure 9529:Higher-order languages 9472: 9448: 9387: 9277: 9210: 9143: 9096: 9049: 8856:Many-sorted signatures 8828:Many-sorted structures 8812: 8781: 8761: 8728: 8704: 8684: 8661: 8637: 8623:If there is a formula 8617: 8590: 8570: 8550: 8530: 8506: 8486: 8464: 8333: 8278: 8254: 8234: 8214: 8163: 8140: 8120: 8096: 8072: 8034: 8007: 7941: 7912: 7888: 7868: 7845: 7736: 7716: 7696: 7565: 7509: 7483: 7451: 7427: 7407: 7387: 7355: 7328: 7314:and every sentence in 7308: 7288: 7264: 7237: 7206: 7183: 7159: 7138: 7105: 7028:homomorphism problem. 6986: 6946: 6922: 6828:is the subcategory of 6792: 6768: 6740: 6711: 6677: 6496: 6443:of σ and any elements 6417: 6362: 6231: 6151: 6072: 5992: 5897: 5836: 5812: 5794:of the two structures 5788: 5754: 5716: 5676: 5652: 5621: 5597: 5573: 5553: 5524: 5490: 5309: 5236:of σ and any elements 5215: 5051: 4978:of σ and any elements 4960: 4897: 4873: 4845: 4821: 4770: 4747: 4727: 4707: 4683: 4663: 4643: 4603: 4580: 4560: 4537: 4486: 4466: 4387: 4360: 4340: 4315: 4288: 4245: 4219: 4168: 4126: 4103: 4068: 4042: 4015: 3988: 3965: 3931: 3889: 3813: 3790: 3740: 3720: 3700: 3632: 3608: 3588: 3568: 3545: 3514: 3490: 3448: 3408: 3368: 3312: 3285: 3259: 3204: 3180: 3153: 3133:(induced) substructure 3125: 3094: 3074: 3044: 3019: 2990: 2959: 2928: 2903: 2874: 2842: 2819: 2771: 2748: 2700: 2674: 2654: 2598: 2534: 2469: 2438: 2215: 2152: 2091: 1899: 1879: 1851: 1826: 1798: 1778: 1756: 1734: 1712: 1690: 1668: 1646: 1624: 1598: 1564: 1485: 1438: 1411: 1391: 1359: 1336: 1301: 1287:-ary) function symbol 1281: 1257: 1186: 1166: 1146: 1126: 1080: 1059: 1039: 1019: 995: 937: 910: 886: 866: 822: 778: 758: 699: 675: 623: 599: 572: 538: 483:of the structure, its 459: 439: 419: 396: 370: 342: 11947:Kolmogorov complexity 11900:Computably enumerable 11800:Model complete theory 11592:Principia Mathematica 10652:Propositional formula 10481:Banach–Tarski paradox 10014:Jacobs, Bart (1999), 9965: 9936: 9934:{\displaystyle N_{0}} 9909: 9889: 9855: 9825: 9803: 9758: 9727: 9617:as well as functions. 9581:Principia Mathematica 9473: 9449: 9424:Other generalizations 9388: 9278: 9211: 9144: 9097: 9050: 8845:many-sorted structure 8813: 8782: 8762: 8729: 8705: 8685: 8662: 8638: 8618: 8591: 8571: 8551: 8531: 8507: 8487: 8465: 8334: 8279: 8255: 8235: 8215: 8196:Implicit definability 8164: 8141: 8121: 8102:with parameters from 8097: 8073: 8035: 8008: 7942: 7913: 7889: 7869: 7846: 7737: 7717: 7697: 7566: 7510: 7484: 7452: 7428: 7408: 7388: 7356: 7329: 7309: 7289: 7265: 7238: 7207: 7184: 7160: 7139: 7113:satisfaction relation 7106: 7059:Satisfaction relation 6987: 6947: 6923: 6793: 6769: 6741: 6712: 6678: 6497: 6439:-ary relation symbol 6418: 6363: 6232: 6152: 6073: 5993: 5915:-ary relation symbol 5898: 5837: 5813: 5789: 5755: 5717: 5677: 5653: 5622: 5598: 5574: 5554: 5525: 5491: 5310: 5232:-ary relation symbol 5216: 5052: 4974:-ary function symbol 4961: 4898: 4874: 4846: 4822: 4803:Given two structures 4771: 4748: 4728: 4708: 4684: 4664: 4644: 4604: 4581: 4561: 4538: 4487: 4467: 4388: 4361: 4341: 4316: 4289: 4246: 4220: 4169: 4127: 4104: 4069: 4043: 4016: 3989: 3966: 3932: 3890: 3814: 3791: 3741: 3721: 3701: 3633: 3614:(in the signature of 3609: 3594:-ary function symbol 3589: 3569: 3546: 3515: 3491: 3449: 3409: 3369: 3313: 3286: 3260: 3205: 3181: 3154: 3126: 3095: 3075: 3073:{\displaystyle \in .} 3045: 3020: 2991: 2960: 2929: 2904: 2875: 2843: 2820: 2772: 2749: 2701: 2675: 2655: 2599: 2535: 2470: 2439: 2216: 2153: 2092: 1900: 1880: 1852: 1827: 1799: 1779: 1757: 1735: 1713: 1691: 1669: 1647: 1625: 1599: 1565: 1486: 1439: 1412: 1392: 1390:{\displaystyle I(s).} 1360: 1337: 1302: 1282: 1258: 1187: 1167: 1147: 1127: 1081: 1060: 1040: 1020: 996: 938: 911: 887: 867: 823: 779: 759: 700: 676: 624: 600: 573: 539: 460: 440: 420: 397: 371: 343: 11895:Church–Turing thesis 11882:Computability theory 11091:continuum hypothesis 10609:Square of opposition 10467:Gödel's completeness 10251:Rautenberg, Wolfgang 10232:, Berlin, New York: 10206:, Berlin, New York: 10050:, Berlin, New York: 9949: 9918: 9898: 9863: 9834: 9812: 9779: 9740: 9702: 9462: 9438: 9287: 9220: 9153: 9106: 9102:, the scalar domain 9059: 9035: 8836:one-sorted structure 8795: 8789:implicitly definable 8771: 8738: 8714: 8694: 8671: 8647: 8627: 8600: 8580: 8560: 8540: 8516: 8496: 8476: 8343: 8288: 8264: 8244: 8224: 8204: 8150: 8130: 8106: 8086: 8048: 8024: 7951: 7922: 7898: 7878: 7858: 7746: 7726: 7706: 7575: 7520: 7499: 7473: 7463:explicitly definable 7437: 7417: 7397: 7377: 7338: 7318: 7298: 7274: 7254: 7223: 7193: 7169: 7148: 7118: 7067: 6956: 6932: 6908: 6898:homomorphism problem 6892:Homomorphism problem 6778: 6754: 6721: 6692: 6512: 6447: 6387: 6241: 6161: 6082: 6002: 5923: 5903:is sometimes called 5867: 5822: 5798: 5764: 5730: 5686: 5662: 5638: 5607: 5583: 5563: 5534: 5505: 5325: 5240: 5067: 4982: 4910: 4883: 4859: 4831: 4807: 4757: 4737: 4717: 4697: 4673: 4653: 4612: 4590: 4570: 4547: 4527: 4476: 4420: 4370: 4350: 4325: 4298: 4255: 4229: 4181: 4144: 4113: 4078: 4052: 4029: 4002: 3975: 3941: 3901: 3822: 3800: 3750: 3730: 3710: 3642: 3618: 3598: 3578: 3555: 3528: 3500: 3460: 3421: 3381: 3321: 3295: 3271: 3214: 3190: 3166: 3139: 3111: 3093:{\displaystyle \in } 3084: 3061: 3052:algebraic structures 3029: 3007: 2973: 2942: 2916: 2884: 2855: 2829: 2783: 2758: 2712: 2684: 2664: 2610: 2546: 2482: 2450: 2225: 2162: 2103: 1909: 1889: 1864: 1839: 1811: 1788: 1766: 1744: 1722: 1700: 1678: 1656: 1634: 1612: 1581: 1495: 1448: 1421: 1401: 1369: 1349: 1335:{\displaystyle I(c)} 1317: 1291: 1280:{\displaystyle =\,0} 1267: 1196: 1176: 1156: 1136: 1092: 1070: 1049: 1029: 1005: 985: 961:algebra over a field 924: 900: 876: 838: 791: 768: 724: 689: 647: 609: 582: 548: 512: 449: 429: 409: 383: 357: 304: 164:first-order theories 152:first-order theories 128:algebraic structures 18:Relational structure 12049:Mathematical object 11940:P versus NP problem 11905:Computable function 11699:Reverse mathematics 11625:Logical consequence 11502:primitive recursive 11497:elementary function 11270:Free/bound variable 11123:Tarski–Grothendieck 10642:Logical connectives 10572:Logical equivalence 10422:Logical consequence 10126:Hinman, P. (2005), 10058:Chang, Chen Chung; 9239: 9172: 8146:is definable using 7369:Definable relations 7270:if the language of 7006:finite model theory 6383:A (σ-)homomorphism 4693:. For example, let 3638:) and all elements 2699:{\displaystyle -x,} 952:algebraic signature 498:domain of discourse 475:Domain of discourse 204:mathematical models 117:finitary operations 12098:Mathematical logic 11847:Transfer principle 11810:Semantics of logic 11795:Categorical theory 11771:Non-standard model 11285:Logical connective 10412:Information theory 10361:Mathematical logic 10108:Mathematical Logic 10060:Keisler, H. Jerome 9960: 9931: 9904: 9884: 9850: 9820: 9798: 9753: 9722: 9673:Mathematical logic 9545:second-order logic 9541:higher-order logic 9535:Second-order logic 9501:, but it is not a 9468: 9444: 9383: 9273: 9223: 9216:, the scalar zero 9206: 9156: 9139: 9092: 9045: 8869:(for vectors) and 8808: 8777: 8757: 8724: 8700: 8683:{\displaystyle R,} 8680: 8657: 8633: 8613: 8586: 8566: 8546: 8526: 8502: 8482: 8460: 8329: 8274: 8250: 8230: 8210: 8159: 8136: 8116: 8092: 8068: 8030: 8003: 7937: 7908: 7884: 7864: 7841: 7732: 7712: 7692: 7561: 7505: 7479: 7447: 7423: 7403: 7383: 7351: 7324: 7304: 7284: 7260: 7233: 7205:{\displaystyle M,} 7202: 7179: 7155: 7134: 7101: 7049:second-order logic 6982: 6942: 6918: 6872:in the category σ- 6788: 6764: 6736: 6707: 6673: 6492: 6413: 6358: 6227: 6147: 6068: 5988: 5893: 5832: 5808: 5784: 5750: 5712: 5672: 5648: 5617: 5593: 5569: 5549: 5520: 5486: 5305: 5211: 5047: 4956: 4893: 4869: 4841: 4817: 4769:{\displaystyle G,} 4766: 4743: 4723: 4703: 4679: 4659: 4639: 4602:{\displaystyle b,} 4599: 4576: 4559:{\displaystyle E.} 4556: 4533: 4482: 4462: 4383: 4356: 4339:{\displaystyle I'} 4336: 4311: 4284: 4241: 4215: 4164: 4122: 4099: 4064: 4041:{\displaystyle B,} 4038: 4014:{\displaystyle B,} 4011: 3987:{\displaystyle B.} 3984: 3961: 3927: 3885: 3812:{\displaystyle B:} 3809: 3786: 3736: 3716: 3696: 3628: 3604: 3584: 3567:{\displaystyle n,} 3564: 3541: 3510: 3486: 3444: 3404: 3364: 3308: 3281: 3255: 3200: 3176: 3149: 3121: 3090: 3070: 3040: 3015: 2986: 2955: 2924: 2899: 2870: 2841:{\displaystyle 1;} 2838: 2815: 2770:{\displaystyle 0,} 2767: 2744: 2696: 2670: 2650: 2594: 2530: 2465: 2434: 2432: 2211: 2148: 2087: 2085: 1895: 1875: 1847: 1822: 1794: 1774: 1752: 1730: 1708: 1686: 1664: 1642: 1620: 1594: 1560: 1481: 1444:one simply writes 1434: 1407: 1387: 1355: 1332: 1297: 1277: 1253: 1182: 1162: 1142: 1122: 1076: 1055: 1035: 1015: 991: 936:{\displaystyle s.} 933: 916:because it is the 906: 882: 862: 818: 774: 754: 695: 671: 619: 595: 568: 534: 455: 435: 415: 392: 369:{\displaystyle A,} 366: 338: 187:Tarskian semantics 32:Mathematical model 12113:Universal algebra 12085: 12084: 12017:Abstract category 11820:Theories of truth 11630:Rule of inference 11620:Natural deduction 11601: 11600: 11146: 11145: 10851:Cartesian product 10756: 10755: 10662:Many-valued logic 10637:Boolean functions 10520:Russell's paradox 10495:diagonal argument 10392:First-order logic 10302:978-90-5699-313-9 10280:978-1-4419-1220-6 10243:978-0-387-98655-5 10217:978-0-387-98760-6 10195:978-0-521-58713-6 10170:978-0-521-30442-9 10141:978-1-56881-262-5 10119:978-0-387-94258-2 10097:978-3-540-26183-4 10073:978-0-7204-0692-4 9907:{\displaystyle -} 9736:of the domain of 9638:978-0-444-51667-1 9414:categorical logic 9402:many-sorted logic 9021: 9020: 8780:{\displaystyle R} 8703:{\displaystyle R} 8690:and the relation 8667:and a new symbol 8589:{\displaystyle R} 8569:{\displaystyle R} 8505:{\displaystyle R} 8472:Here the formula 8253:{\displaystyle M} 8233:{\displaystyle R} 8213:{\displaystyle n} 8172:Some authors use 8139:{\displaystyle R} 8033:{\displaystyle R} 7887:{\displaystyle M} 7867:{\displaystyle m} 7715:{\displaystyle R} 7467:Beth definability 7433:of the structure 7426:{\displaystyle M} 7406:{\displaystyle R} 7386:{\displaystyle n} 7327:{\displaystyle T} 7307:{\displaystyle T} 7263:{\displaystyle T} 7025:conjunctive query 7002:complexity of CSP 6688:(where as before 5572:{\displaystyle R} 4782:induced subgraphs 4753:is a subgraph of 4746:{\displaystyle H} 4726:{\displaystyle H} 4706:{\displaystyle G} 4682:{\displaystyle b} 4662:{\displaystyle a} 4637: 4579:{\displaystyle a} 4359:{\displaystyle B} 3897:For every subset 3739:{\displaystyle n} 3719:{\displaystyle f} 3607:{\displaystyle f} 3587:{\displaystyle n} 2673:{\displaystyle x} 1797:{\displaystyle A} 1410:{\displaystyle f} 1358:{\displaystyle s} 1300:{\displaystyle c} 1185:{\displaystyle n} 1165:{\displaystyle n} 1145:{\displaystyle R} 1079:{\displaystyle n} 1058:{\displaystyle n} 1038:{\displaystyle f} 994:{\displaystyle I} 975:in another model. 909:{\displaystyle s} 885:{\displaystyle s} 777:{\displaystyle s} 735: 698:{\displaystyle S} 639:Signature (logic) 418:{\displaystyle I} 270: 269: 227:relational models 225:, in the form of 179:first-order logic 148:universal algebra 101:universal algebra 97: 96: 89: 16:(Redirected from 12120: 12076: 12075: 12027:History of logic 12022:Category of sets 11915:Decision problem 11694:Ordinal analysis 11635:Sequent calculus 11533:Boolean algebras 11473: 11472: 11447: 11418:logical/constant 11172: 11171: 11158: 11081:Zermelo–Fraenkel 10832:Set operations: 10767: 10766: 10704: 10535: 10534: 10515:Löwenheim–Skolem 10402:Formal semantics 10354: 10347: 10340: 10331: 10330: 10305: 10283: 10257:(3rd ed.), 10246: 10231: 10220: 10198: 10173: 10158: 10144: 10122: 10111: 10100: 10076: 10054: 10031: 10030: 10011: 10005: 10004: 9976: 9970: 9969: 9967: 9966: 9961: 9956: 9940: 9938: 9937: 9932: 9930: 9929: 9913: 9911: 9910: 9905: 9893: 9891: 9890: 9885: 9859: 9857: 9856: 9851: 9846: 9845: 9829: 9827: 9826: 9821: 9819: 9807: 9805: 9804: 9799: 9794: 9786: 9773: 9764: 9762: 9760: 9759: 9754: 9749: 9748: 9731: 9729: 9728: 9723: 9721: 9716: 9715: 9709: 9696: 9690: 9683: 9677: 9676: 9668: 9662: 9659: 9649: 9643: 9642: 9624: 9618: 9611: 9576:Bertrand Russell 9555:In the study of 9499:elementary class 9477: 9475: 9474: 9469: 9453: 9451: 9450: 9445: 9429:Partial algebras 9392: 9390: 9389: 9384: 9382: 9381: 9376: 9370: 9369: 9363: 9355: 9354: 9349: 9343: 9342: 9336: 9328: 9327: 9322: 9316: 9315: 9309: 9301: 9300: 9299: 9282: 9280: 9279: 9274: 9272: 9271: 9266: 9260: 9259: 9253: 9238: 9237: 9231: 9215: 9213: 9212: 9207: 9205: 9204: 9199: 9193: 9192: 9186: 9171: 9170: 9164: 9148: 9146: 9145: 9140: 9132: 9131: 9126: 9120: 9119: 9113: 9101: 9099: 9098: 9093: 9085: 9084: 9079: 9073: 9072: 9066: 9054: 9052: 9051: 9046: 9044: 9043: 8876: 8875: 8847: 8846: 8838: 8837: 8817: 8815: 8814: 8809: 8804: 8803: 8786: 8784: 8783: 8778: 8766: 8764: 8763: 8758: 8747: 8746: 8733: 8731: 8730: 8725: 8723: 8722: 8709: 8707: 8706: 8701: 8689: 8687: 8686: 8681: 8666: 8664: 8663: 8658: 8656: 8655: 8642: 8640: 8639: 8634: 8622: 8620: 8619: 8614: 8609: 8608: 8595: 8593: 8592: 8587: 8575: 8573: 8572: 8567: 8556:may not mention 8555: 8553: 8552: 8547: 8535: 8533: 8532: 8527: 8525: 8524: 8511: 8509: 8508: 8503: 8491: 8489: 8488: 8483: 8469: 8467: 8466: 8461: 8450: 8449: 8431: 8430: 8412: 8411: 8402: 8401: 8386: 8385: 8367: 8366: 8338: 8336: 8335: 8330: 8325: 8324: 8306: 8305: 8283: 8281: 8280: 8275: 8273: 8272: 8259: 8257: 8256: 8251: 8240:on the universe 8239: 8237: 8236: 8231: 8219: 8217: 8216: 8211: 8168: 8166: 8165: 8160: 8145: 8143: 8142: 8137: 8125: 8123: 8122: 8117: 8115: 8114: 8101: 8099: 8098: 8093: 8077: 8075: 8074: 8069: 8067: 8062: 8061: 8055: 8039: 8037: 8036: 8031: 8012: 8010: 8009: 8004: 7960: 7959: 7946: 7944: 7943: 7938: 7917: 7915: 7914: 7909: 7907: 7906: 7894:is definable in 7893: 7891: 7890: 7885: 7873: 7871: 7870: 7865: 7850: 7848: 7847: 7842: 7837: 7836: 7818: 7817: 7799: 7798: 7780: 7779: 7761: 7760: 7741: 7739: 7738: 7733: 7721: 7719: 7718: 7713: 7702:In other words, 7701: 7699: 7698: 7693: 7682: 7681: 7663: 7662: 7644: 7643: 7634: 7633: 7618: 7617: 7599: 7598: 7570: 7568: 7567: 7562: 7557: 7556: 7538: 7537: 7514: 7512: 7511: 7506: 7488: 7486: 7485: 7480: 7456: 7454: 7453: 7448: 7446: 7445: 7432: 7430: 7429: 7424: 7412: 7410: 7409: 7404: 7392: 7390: 7389: 7384: 7360: 7358: 7357: 7352: 7347: 7346: 7334:is satisfied by 7333: 7331: 7330: 7325: 7313: 7311: 7310: 7305: 7293: 7291: 7290: 7285: 7283: 7282: 7269: 7267: 7266: 7261: 7243:is said to be a 7242: 7240: 7239: 7234: 7232: 7231: 7211: 7209: 7208: 7203: 7188: 7186: 7185: 7180: 7178: 7177: 7164: 7162: 7161: 7156: 7143: 7141: 7140: 7135: 7127: 7126: 7110: 7108: 7107: 7102: 7076: 7075: 7017:relational model 6991: 6989: 6988: 6983: 6981: 6980: 6971: 6970: 6951: 6949: 6948: 6943: 6941: 6940: 6927: 6925: 6924: 6919: 6917: 6916: 6876:, and therefore 6797: 6795: 6794: 6789: 6787: 6786: 6773: 6771: 6770: 6765: 6763: 6762: 6745: 6743: 6742: 6737: 6735: 6734: 6733: 6716: 6714: 6713: 6708: 6706: 6705: 6704: 6682: 6680: 6679: 6674: 6672: 6671: 6670: 6651: 6650: 6623: 6622: 6601: 6600: 6577: 6576: 6575: 6559: 6558: 6540: 6539: 6527: 6526: 6501: 6499: 6498: 6493: 6491: 6490: 6472: 6471: 6459: 6458: 6423:is called a (σ-) 6422: 6420: 6419: 6414: 6412: 6411: 6402: 6401: 6367: 6365: 6364: 6359: 6351: 6350: 6332: 6331: 6308: 6307: 6289: 6288: 6272: 6271: 6253: 6252: 6236: 6234: 6233: 6228: 6226: 6225: 6224: 6208: 6207: 6189: 6188: 6176: 6175: 6156: 6154: 6153: 6148: 6146: 6141: 6140: 6134: 6126: 6125: 6107: 6106: 6094: 6093: 6077: 6075: 6074: 6069: 6067: 6066: 6065: 6049: 6048: 6030: 6029: 6017: 6016: 5997: 5995: 5994: 5989: 5987: 5982: 5981: 5975: 5967: 5966: 5948: 5947: 5935: 5934: 5902: 5900: 5899: 5894: 5892: 5891: 5882: 5881: 5841: 5839: 5838: 5833: 5831: 5830: 5817: 5815: 5814: 5809: 5807: 5806: 5793: 5791: 5790: 5785: 5783: 5778: 5777: 5771: 5759: 5757: 5756: 5751: 5749: 5744: 5743: 5737: 5721: 5719: 5718: 5713: 5711: 5710: 5701: 5700: 5681: 5679: 5678: 5673: 5671: 5670: 5657: 5655: 5654: 5649: 5647: 5646: 5626: 5624: 5623: 5618: 5616: 5615: 5602: 5600: 5599: 5594: 5592: 5591: 5578: 5576: 5575: 5570: 5558: 5556: 5555: 5550: 5548: 5547: 5546: 5529: 5527: 5526: 5521: 5519: 5518: 5517: 5495: 5493: 5492: 5487: 5485: 5484: 5483: 5464: 5463: 5436: 5435: 5414: 5413: 5390: 5389: 5388: 5372: 5371: 5353: 5352: 5340: 5339: 5314: 5312: 5311: 5306: 5304: 5299: 5298: 5292: 5284: 5283: 5265: 5264: 5252: 5251: 5220: 5218: 5217: 5212: 5204: 5203: 5176: 5175: 5154: 5153: 5123: 5122: 5104: 5103: 5091: 5090: 5056: 5054: 5053: 5048: 5046: 5041: 5040: 5034: 5026: 5025: 5007: 5006: 4994: 4993: 4965: 4963: 4962: 4957: 4955: 4950: 4949: 4943: 4935: 4930: 4929: 4923: 4902: 4900: 4899: 4894: 4892: 4891: 4878: 4876: 4875: 4870: 4868: 4867: 4853:(σ-)homomorphism 4850: 4848: 4847: 4842: 4840: 4839: 4826: 4824: 4823: 4818: 4816: 4815: 4775: 4773: 4772: 4767: 4752: 4750: 4749: 4744: 4732: 4730: 4729: 4724: 4712: 4710: 4709: 4704: 4688: 4686: 4685: 4680: 4668: 4666: 4665: 4660: 4648: 4646: 4645: 4640: 4638: 4635: 4608: 4606: 4605: 4600: 4585: 4583: 4582: 4577: 4565: 4563: 4562: 4557: 4542: 4540: 4539: 4534: 4494:rational numbers 4491: 4489: 4488: 4483: 4471: 4469: 4468: 4463: 4392: 4390: 4389: 4384: 4379: 4378: 4365: 4363: 4362: 4357: 4345: 4343: 4342: 4337: 4335: 4320: 4318: 4317: 4312: 4307: 4306: 4293: 4291: 4290: 4285: 4280: 4250: 4248: 4247: 4242: 4224: 4222: 4221: 4216: 4190: 4189: 4173: 4171: 4170: 4165: 4163: 4158: 4157: 4151: 4131: 4129: 4128: 4123: 4108: 4106: 4105: 4100: 4098: 4097: 4096: 4073: 4071: 4070: 4065: 4047: 4045: 4044: 4039: 4020: 4018: 4017: 4012: 3993: 3991: 3990: 3985: 3970: 3968: 3967: 3962: 3960: 3955: 3954: 3948: 3936: 3934: 3933: 3928: 3926: 3921: 3920: 3914: 3894: 3892: 3891: 3886: 3872: 3871: 3853: 3852: 3840: 3839: 3818: 3816: 3815: 3810: 3795: 3793: 3792: 3787: 3785: 3784: 3772: 3771: 3762: 3761: 3745: 3743: 3742: 3737: 3725: 3723: 3722: 3717: 3705: 3703: 3702: 3697: 3686: 3685: 3667: 3666: 3654: 3653: 3637: 3635: 3634: 3629: 3627: 3626: 3613: 3611: 3610: 3605: 3593: 3591: 3590: 3585: 3573: 3571: 3570: 3565: 3550: 3548: 3547: 3542: 3537: 3536: 3519: 3517: 3516: 3511: 3509: 3508: 3495: 3493: 3492: 3487: 3485: 3480: 3479: 3473: 3453: 3451: 3450: 3445: 3440: 3439: 3430: 3429: 3413: 3411: 3410: 3405: 3400: 3395: 3394: 3388: 3373: 3371: 3370: 3365: 3360: 3355: 3354: 3348: 3340: 3335: 3334: 3328: 3317: 3315: 3314: 3309: 3304: 3303: 3290: 3288: 3287: 3282: 3280: 3279: 3264: 3262: 3261: 3256: 3248: 3247: 3229: 3228: 3209: 3207: 3206: 3201: 3199: 3198: 3185: 3183: 3182: 3177: 3175: 3174: 3158: 3156: 3155: 3150: 3148: 3147: 3130: 3128: 3127: 3122: 3120: 3119: 3099: 3097: 3096: 3091: 3079: 3077: 3076: 3071: 3049: 3047: 3046: 3041: 3024: 3022: 3021: 3016: 2999:A signature for 2995: 2993: 2992: 2987: 2985: 2984: 2964: 2962: 2961: 2956: 2954: 2953: 2933: 2931: 2930: 2925: 2923: 2908: 2906: 2905: 2900: 2898: 2897: 2896: 2879: 2877: 2876: 2871: 2869: 2868: 2867: 2847: 2845: 2844: 2839: 2824: 2822: 2821: 2816: 2814: 2797: 2796: 2795: 2776: 2774: 2773: 2768: 2753: 2751: 2750: 2745: 2743: 2726: 2725: 2724: 2705: 2703: 2702: 2697: 2679: 2677: 2676: 2671: 2659: 2657: 2656: 2651: 2649: 2641: 2624: 2623: 2622: 2603: 2601: 2600: 2595: 2593: 2585: 2577: 2560: 2559: 2558: 2539: 2537: 2536: 2531: 2529: 2521: 2513: 2496: 2495: 2494: 2474: 2472: 2471: 2466: 2464: 2463: 2462: 2443: 2441: 2440: 2435: 2433: 2420: 2405: 2404: 2379: 2364: 2363: 2338: 2323: 2322: 2297: 2282: 2281: 2256: 2241: 2240: 2220: 2218: 2217: 2212: 2174: 2173: 2157: 2155: 2154: 2149: 2144: 2143: 2131: 2130: 2115: 2114: 2096: 2094: 2093: 2088: 2086: 2079: 2078: 2077: 2064: 2063: 2051: 2036: 2035: 2022: 2021: 2020: 2007: 2006: 1994: 1979: 1978: 1965: 1964: 1963: 1950: 1949: 1937: 1922: 1921: 1904: 1902: 1901: 1896: 1884: 1882: 1881: 1876: 1871: 1856: 1854: 1853: 1848: 1846: 1831: 1829: 1828: 1823: 1818: 1806:rational numbers 1803: 1801: 1800: 1795: 1783: 1781: 1780: 1775: 1773: 1761: 1759: 1758: 1753: 1751: 1739: 1737: 1736: 1731: 1729: 1717: 1715: 1714: 1709: 1707: 1695: 1693: 1692: 1687: 1685: 1673: 1671: 1670: 1665: 1663: 1651: 1649: 1648: 1643: 1641: 1629: 1627: 1626: 1621: 1619: 1603: 1601: 1600: 1595: 1593: 1592: 1569: 1567: 1566: 1561: 1556: 1551: 1550: 1544: 1536: 1535: 1530: 1524: 1523: 1517: 1509: 1508: 1507: 1490: 1488: 1487: 1482: 1480: 1479: 1470: 1469: 1464: 1463: 1443: 1441: 1440: 1435: 1430: 1429: 1416: 1414: 1413: 1408: 1397:For example, if 1396: 1394: 1393: 1388: 1364: 1362: 1361: 1356: 1341: 1339: 1338: 1333: 1306: 1304: 1303: 1298: 1286: 1284: 1283: 1278: 1262: 1260: 1259: 1254: 1252: 1251: 1250: 1210: 1209: 1208: 1191: 1189: 1188: 1183: 1171: 1169: 1168: 1163: 1151: 1149: 1148: 1143: 1131: 1129: 1128: 1123: 1106: 1105: 1104: 1085: 1083: 1082: 1077: 1064: 1062: 1061: 1056: 1044: 1042: 1041: 1036: 1024: 1022: 1021: 1016: 1014: 1013: 1000: 998: 997: 992: 942: 940: 939: 934: 915: 913: 912: 907: 891: 889: 888: 883: 871: 869: 868: 863: 827: 825: 824: 819: 783: 781: 780: 775: 763: 761: 760: 755: 753: 752: 747: 733: 714:relation symbols 708:function symbols 704: 702: 701: 696: 680: 678: 677: 672: 628: 626: 625: 620: 618: 617: 604: 602: 601: 596: 591: 590: 577: 575: 574: 569: 567: 562: 561: 555: 543: 541: 540: 535: 530: 529: 464: 462: 461: 456: 444: 442: 441: 436: 424: 422: 421: 416: 401: 399: 398: 393: 375: 373: 372: 367: 348:consisting of a 347: 345: 344: 339: 313: 312: 282:Richard Dedekind 265: 262: 244: 237: 156:relation symbols 92: 85: 81: 78: 72: 67:this article by 58:inline citations 45: 44: 37: 21: 12128: 12127: 12123: 12122: 12121: 12119: 12118: 12117: 12088: 12087: 12086: 12081: 12070: 12063: 12008:Category theory 11998:Algebraic logic 11981: 11952:Lambda calculus 11890:Church encoding 11876: 11852:Truth predicate 11708: 11674:Complete theory 11597: 11466: 11462: 11458: 11453: 11445: 11165: and  11161: 11156: 11142: 11118:New Foundations 11086:axiom of choice 11069: 11031:Gödel numbering 10971: and  10963: 10867: 10752: 10702: 10683: 10632:Boolean algebra 10618: 10582:Equiconsistency 10547:Classical logic 10524: 10505:Halting problem 10493: and  10469: and  10457: and  10456: 10451:Theorems ( 10446: 10363: 10358: 10320:Classical Logic 10312: 10303: 10281: 10244: 10234:Springer-Verlag 10218: 10208:Springer-Verlag 10196: 10178:Hodges, Wilfrid 10171: 10149:Hodges, Wilfrid 10142: 10120: 10098: 10088:Springer-Verlag 10074: 10052:Springer-Verlag 10040: 10035: 10034: 10028: 10012: 10008: 9977: 9973: 9952: 9950: 9947: 9946: 9925: 9921: 9919: 9916: 9915: 9899: 9896: 9895: 9864: 9861: 9860: 9841: 9837: 9835: 9832: 9831: 9815: 9813: 9810: 9809: 9790: 9782: 9780: 9777: 9776: 9774: 9767: 9744: 9743: 9741: 9738: 9737: 9717: 9711: 9710: 9705: 9703: 9700: 9699: 9697: 9693: 9687:inclusive logic 9684: 9680: 9669: 9665: 9651: 9650: 9646: 9639: 9625: 9621: 9612: 9608: 9603: 9590: 9561:category theory 9553: 9537: 9531: 9515: 9463: 9460: 9459: 9439: 9436: 9435: 9431: 9426: 9377: 9372: 9371: 9365: 9364: 9359: 9350: 9345: 9344: 9338: 9337: 9332: 9323: 9318: 9317: 9311: 9310: 9305: 9295: 9294: 9290: 9288: 9285: 9284: 9267: 9262: 9261: 9255: 9254: 9249: 9233: 9232: 9227: 9221: 9218: 9217: 9200: 9195: 9194: 9188: 9187: 9182: 9166: 9165: 9160: 9154: 9151: 9150: 9127: 9122: 9121: 9115: 9114: 9109: 9107: 9104: 9103: 9080: 9075: 9074: 9068: 9067: 9062: 9060: 9057: 9056: 9039: 9038: 9036: 9033: 9032: 8991: 8974: 8953: 8936: 8930: 8913: 8892: 8886: 8844: 8843: 8835: 8834: 8830: 8799: 8798: 8796: 8793: 8792: 8772: 8769: 8768: 8742: 8741: 8739: 8736: 8735: 8718: 8717: 8715: 8712: 8711: 8695: 8692: 8691: 8672: 8669: 8668: 8651: 8650: 8648: 8645: 8644: 8628: 8625: 8624: 8604: 8603: 8601: 8598: 8597: 8581: 8578: 8577: 8561: 8558: 8557: 8541: 8538: 8537: 8520: 8519: 8517: 8514: 8513: 8497: 8494: 8493: 8477: 8474: 8473: 8445: 8441: 8426: 8422: 8407: 8406: 8397: 8393: 8381: 8377: 8362: 8358: 8344: 8341: 8340: 8320: 8316: 8301: 8297: 8289: 8286: 8285: 8268: 8267: 8265: 8262: 8261: 8245: 8242: 8241: 8225: 8222: 8221: 8205: 8202: 8201: 8198: 8151: 8148: 8147: 8131: 8128: 8127: 8110: 8109: 8107: 8104: 8103: 8087: 8084: 8083: 8063: 8057: 8056: 8051: 8049: 8046: 8045: 8025: 8022: 8021: 8018: 7955: 7954: 7952: 7949: 7948: 7923: 7920: 7919: 7902: 7901: 7899: 7896: 7895: 7879: 7876: 7875: 7859: 7856: 7855: 7832: 7828: 7813: 7809: 7794: 7793: 7775: 7771: 7756: 7752: 7747: 7744: 7743: 7727: 7724: 7723: 7707: 7704: 7703: 7677: 7673: 7658: 7654: 7639: 7638: 7629: 7625: 7613: 7609: 7594: 7590: 7576: 7573: 7572: 7552: 7548: 7533: 7529: 7521: 7518: 7517: 7500: 7497: 7496: 7474: 7471: 7470: 7441: 7440: 7438: 7435: 7434: 7418: 7415: 7414: 7398: 7395: 7394: 7378: 7375: 7374: 7371: 7342: 7341: 7339: 7336: 7335: 7319: 7316: 7315: 7299: 7296: 7295: 7278: 7277: 7275: 7272: 7271: 7255: 7252: 7251: 7227: 7226: 7224: 7221: 7220: 7194: 7191: 7190: 7173: 7172: 7170: 7167: 7166: 7149: 7146: 7145: 7122: 7121: 7119: 7116: 7115: 7071: 7070: 7068: 7065: 7064: 7061: 7044: 7034: 7013:database theory 6976: 6975: 6966: 6965: 6957: 6954: 6953: 6936: 6935: 6933: 6930: 6929: 6912: 6911: 6909: 6906: 6905: 6894: 6846: 6798:respectively). 6782: 6781: 6779: 6776: 6775: 6758: 6757: 6755: 6752: 6751: 6729: 6728: 6724: 6722: 6719: 6718: 6700: 6699: 6695: 6693: 6690: 6689: 6666: 6665: 6661: 6646: 6642: 6618: 6614: 6596: 6592: 6571: 6570: 6566: 6554: 6550: 6535: 6531: 6522: 6518: 6513: 6510: 6509: 6486: 6482: 6467: 6463: 6454: 6450: 6448: 6445: 6444: 6407: 6406: 6397: 6396: 6388: 6385: 6384: 6381: 6346: 6342: 6327: 6323: 6303: 6299: 6284: 6280: 6267: 6263: 6248: 6244: 6242: 6239: 6238: 6220: 6219: 6215: 6203: 6199: 6184: 6180: 6171: 6167: 6162: 6159: 6158: 6142: 6136: 6135: 6130: 6121: 6117: 6102: 6098: 6089: 6085: 6083: 6080: 6079: 6061: 6060: 6056: 6044: 6040: 6025: 6021: 6012: 6008: 6003: 6000: 5999: 5983: 5977: 5976: 5971: 5962: 5958: 5943: 5939: 5930: 5926: 5924: 5921: 5920: 5887: 5886: 5877: 5876: 5868: 5865: 5864: 5863:A homomorphism 5826: 5825: 5823: 5820: 5819: 5802: 5801: 5799: 5796: 5795: 5779: 5773: 5772: 5767: 5765: 5762: 5761: 5745: 5739: 5738: 5733: 5731: 5728: 5727: 5706: 5705: 5696: 5695: 5687: 5684: 5683: 5666: 5665: 5663: 5660: 5659: 5642: 5641: 5639: 5636: 5635: 5630:A homomorphism 5611: 5610: 5608: 5605: 5604: 5587: 5586: 5584: 5581: 5580: 5564: 5561: 5560: 5542: 5541: 5537: 5535: 5532: 5531: 5513: 5512: 5508: 5506: 5503: 5502: 5479: 5478: 5474: 5459: 5455: 5431: 5427: 5409: 5405: 5384: 5383: 5379: 5367: 5363: 5348: 5344: 5335: 5331: 5326: 5323: 5322: 5300: 5294: 5293: 5288: 5279: 5275: 5260: 5256: 5247: 5243: 5241: 5238: 5237: 5199: 5195: 5171: 5167: 5149: 5145: 5118: 5114: 5099: 5095: 5086: 5082: 5068: 5065: 5064: 5042: 5036: 5035: 5030: 5021: 5017: 5002: 4998: 4989: 4985: 4983: 4980: 4979: 4951: 4945: 4944: 4939: 4931: 4925: 4924: 4919: 4911: 4908: 4907: 4887: 4886: 4884: 4881: 4880: 4863: 4862: 4860: 4857: 4856: 4835: 4834: 4832: 4829: 4828: 4811: 4810: 4808: 4805: 4804: 4801: 4796: 4790: 4758: 4755: 4754: 4738: 4735: 4734: 4718: 4715: 4714: 4698: 4695: 4694: 4674: 4671: 4670: 4654: 4651: 4650: 4634: 4613: 4610: 4609: 4591: 4588: 4587: 4571: 4568: 4567: 4548: 4545: 4544: 4528: 4525: 4524: 4502:complex numbers 4477: 4474: 4473: 4421: 4418: 4417: 4414: 4374: 4373: 4371: 4368: 4367: 4351: 4348: 4347: 4328: 4326: 4323: 4322: 4302: 4301: 4299: 4296: 4295: 4273: 4256: 4253: 4252: 4230: 4227: 4226: 4185: 4184: 4182: 4179: 4178: 4159: 4153: 4152: 4147: 4145: 4142: 4141: 4114: 4111: 4110: 4109:. The operator 4092: 4091: 4087: 4079: 4076: 4075: 4053: 4050: 4049: 4048:and denoted by 4030: 4027: 4026: 4003: 4000: 3999: 3976: 3973: 3972: 3956: 3950: 3949: 3944: 3942: 3939: 3938: 3922: 3916: 3915: 3910: 3902: 3899: 3898: 3867: 3863: 3848: 3844: 3835: 3831: 3823: 3820: 3819: 3801: 3798: 3797: 3780: 3776: 3767: 3763: 3757: 3753: 3751: 3748: 3747: 3731: 3728: 3727: 3711: 3708: 3707: 3681: 3677: 3662: 3658: 3649: 3645: 3643: 3640: 3639: 3622: 3621: 3619: 3616: 3615: 3599: 3596: 3595: 3579: 3576: 3575: 3556: 3553: 3552: 3532: 3531: 3529: 3526: 3525: 3504: 3503: 3501: 3498: 3497: 3481: 3475: 3474: 3469: 3461: 3458: 3457: 3435: 3434: 3425: 3424: 3422: 3419: 3418: 3396: 3390: 3389: 3384: 3382: 3379: 3378: 3356: 3350: 3349: 3344: 3336: 3330: 3329: 3324: 3322: 3319: 3318: 3299: 3298: 3296: 3293: 3292: 3275: 3274: 3272: 3269: 3268: 3243: 3242: 3224: 3223: 3215: 3212: 3211: 3194: 3193: 3191: 3188: 3187: 3170: 3169: 3167: 3164: 3163: 3143: 3142: 3140: 3137: 3136: 3115: 3114: 3112: 3109: 3108: 3106: 3085: 3082: 3081: 3062: 3059: 3058: 3030: 3027: 3026: 3008: 3005: 3004: 2980: 2976: 2974: 2971: 2970: 2949: 2945: 2943: 2940: 2939: 2919: 2917: 2914: 2913: 2892: 2891: 2887: 2885: 2882: 2881: 2863: 2862: 2858: 2856: 2853: 2852: 2830: 2827: 2826: 2810: 2791: 2790: 2786: 2784: 2781: 2780: 2759: 2756: 2755: 2739: 2720: 2719: 2715: 2713: 2710: 2709: 2685: 2682: 2681: 2665: 2662: 2661: 2645: 2637: 2618: 2617: 2613: 2611: 2608: 2607: 2589: 2581: 2573: 2554: 2553: 2549: 2547: 2544: 2543: 2525: 2517: 2509: 2490: 2489: 2485: 2483: 2480: 2479: 2458: 2457: 2453: 2451: 2448: 2447: 2431: 2430: 2419: 2406: 2400: 2396: 2393: 2392: 2378: 2365: 2359: 2355: 2352: 2351: 2337: 2324: 2318: 2314: 2311: 2310: 2296: 2283: 2277: 2273: 2270: 2269: 2255: 2242: 2236: 2232: 2228: 2226: 2223: 2222: 2169: 2165: 2163: 2160: 2159: 2139: 2135: 2126: 2122: 2110: 2106: 2104: 2101: 2100: 2084: 2083: 2073: 2072: 2068: 2059: 2055: 2047: 2037: 2031: 2030: 2027: 2026: 2016: 2015: 2011: 2002: 1998: 1990: 1980: 1974: 1973: 1970: 1969: 1959: 1958: 1954: 1945: 1941: 1933: 1923: 1917: 1916: 1912: 1910: 1907: 1906: 1890: 1887: 1886: 1867: 1865: 1862: 1861: 1859:complex numbers 1842: 1840: 1837: 1836: 1814: 1812: 1809: 1808: 1789: 1786: 1785: 1769: 1767: 1764: 1763: 1747: 1745: 1742: 1741: 1725: 1723: 1720: 1719: 1703: 1701: 1698: 1697: 1681: 1679: 1676: 1675: 1659: 1657: 1654: 1653: 1637: 1635: 1632: 1631: 1615: 1613: 1610: 1609: 1588: 1584: 1582: 1579: 1578: 1575: 1552: 1546: 1545: 1540: 1531: 1526: 1525: 1519: 1518: 1513: 1503: 1502: 1498: 1496: 1493: 1492: 1475: 1474: 1465: 1459: 1458: 1457: 1449: 1446: 1445: 1425: 1424: 1422: 1419: 1418: 1402: 1399: 1398: 1370: 1367: 1366: 1350: 1347: 1346: 1318: 1315: 1314: 1310:constant symbol 1292: 1289: 1288: 1268: 1265: 1264: 1234: 1233: 1229: 1204: 1203: 1199: 1197: 1194: 1193: 1177: 1174: 1173: 1172:is assigned an 1157: 1154: 1153: 1137: 1134: 1133: 1100: 1099: 1095: 1093: 1090: 1089: 1071: 1068: 1067: 1065:is assigned an 1050: 1047: 1046: 1030: 1027: 1026: 1009: 1008: 1006: 1003: 1002: 986: 983: 982: 976: 969: 925: 922: 921: 901: 898: 897: 877: 874: 873: 839: 836: 835: 792: 789: 788: 769: 766: 765: 748: 743: 742: 725: 722: 721: 690: 687: 686: 648: 645: 644: 641: 635: 613: 612: 610: 607: 606: 586: 585: 583: 580: 579: 563: 557: 556: 551: 549: 546: 545: 525: 524: 513: 510: 509: 477: 471: 450: 447: 446: 430: 427: 426: 410: 407: 406: 384: 381: 380: 358: 355: 354: 308: 307: 305: 302: 301: 294: 266: 260: 257: 250:needs expansion 235: 219:database theory 208:interpretations 93: 82: 76: 73: 63:Please help to 62: 46: 42: 35: 28: 23: 22: 15: 12: 11: 5: 12126: 12116: 12115: 12110: 12105: 12100: 12083: 12082: 12068: 12065: 12064: 12062: 12061: 12056: 12051: 12046: 12041: 12040: 12039: 12029: 12024: 12019: 12010: 12005: 12000: 11995: 11993:Abstract logic 11989: 11987: 11983: 11982: 11980: 11979: 11974: 11972:Turing machine 11969: 11964: 11959: 11954: 11949: 11944: 11943: 11942: 11937: 11932: 11927: 11922: 11912: 11910:Computable set 11907: 11902: 11897: 11892: 11886: 11884: 11878: 11877: 11875: 11874: 11869: 11864: 11859: 11854: 11849: 11844: 11839: 11838: 11837: 11832: 11827: 11817: 11812: 11807: 11805:Satisfiability 11802: 11797: 11792: 11791: 11790: 11780: 11779: 11778: 11768: 11767: 11766: 11761: 11756: 11751: 11746: 11736: 11735: 11734: 11729: 11722:Interpretation 11718: 11716: 11710: 11709: 11707: 11706: 11701: 11696: 11691: 11686: 11676: 11671: 11670: 11669: 11668: 11667: 11657: 11652: 11642: 11637: 11632: 11627: 11622: 11617: 11611: 11609: 11603: 11602: 11599: 11598: 11596: 11595: 11587: 11586: 11585: 11584: 11579: 11578: 11577: 11572: 11567: 11547: 11546: 11545: 11543:minimal axioms 11540: 11529: 11528: 11527: 11516: 11515: 11514: 11509: 11504: 11499: 11494: 11489: 11476: 11474: 11455: 11454: 11452: 11451: 11450: 11449: 11437: 11432: 11431: 11430: 11425: 11420: 11415: 11405: 11400: 11395: 11390: 11389: 11388: 11383: 11373: 11372: 11371: 11366: 11361: 11356: 11346: 11341: 11340: 11339: 11334: 11329: 11319: 11318: 11317: 11312: 11307: 11302: 11297: 11292: 11282: 11277: 11272: 11267: 11266: 11265: 11260: 11255: 11250: 11240: 11235: 11233:Formation rule 11230: 11225: 11224: 11223: 11218: 11208: 11207: 11206: 11196: 11191: 11186: 11181: 11175: 11169: 11152:Formal systems 11148: 11147: 11144: 11143: 11141: 11140: 11135: 11130: 11125: 11120: 11115: 11110: 11105: 11100: 11095: 11094: 11093: 11088: 11077: 11075: 11071: 11070: 11068: 11067: 11066: 11065: 11055: 11050: 11049: 11048: 11041:Large cardinal 11038: 11033: 11028: 11023: 11018: 11004: 11003: 11002: 10997: 10992: 10977: 10975: 10965: 10964: 10962: 10961: 10960: 10959: 10954: 10949: 10939: 10934: 10929: 10924: 10919: 10914: 10909: 10904: 10899: 10894: 10889: 10884: 10878: 10876: 10869: 10868: 10866: 10865: 10864: 10863: 10858: 10853: 10848: 10843: 10838: 10830: 10829: 10828: 10823: 10813: 10808: 10806:Extensionality 10803: 10801:Ordinal number 10798: 10788: 10783: 10782: 10781: 10770: 10764: 10758: 10757: 10754: 10753: 10751: 10750: 10745: 10740: 10735: 10730: 10725: 10720: 10719: 10718: 10708: 10707: 10706: 10693: 10691: 10685: 10684: 10682: 10681: 10680: 10679: 10674: 10669: 10659: 10654: 10649: 10644: 10639: 10634: 10628: 10626: 10620: 10619: 10617: 10616: 10611: 10606: 10601: 10596: 10591: 10586: 10585: 10584: 10574: 10569: 10564: 10559: 10554: 10549: 10543: 10541: 10532: 10526: 10525: 10523: 10522: 10517: 10512: 10507: 10502: 10497: 10485:Cantor's  10483: 10478: 10473: 10463: 10461: 10448: 10447: 10445: 10444: 10439: 10434: 10429: 10424: 10419: 10414: 10409: 10404: 10399: 10394: 10389: 10384: 10383: 10382: 10371: 10369: 10365: 10364: 10357: 10356: 10349: 10342: 10334: 10328: 10327: 10311: 10310:External links 10308: 10307: 10306: 10301: 10284: 10279: 10247: 10242: 10221: 10216: 10199: 10194: 10174: 10169: 10145: 10140: 10123: 10118: 10101: 10096: 10077: 10072: 10055: 10039: 10036: 10033: 10032: 10026: 10006: 9971: 9959: 9955: 9928: 9924: 9903: 9883: 9880: 9877: 9874: 9871: 9868: 9849: 9844: 9840: 9818: 9797: 9793: 9789: 9785: 9765: 9752: 9747: 9720: 9714: 9708: 9691: 9678: 9663: 9644: 9637: 9619: 9605: 9604: 9602: 9599: 9598: 9597: 9589: 9586: 9552: 9549: 9533:Main article: 9530: 9527: 9514: 9511: 9467: 9443: 9430: 9427: 9425: 9422: 9380: 9375: 9368: 9362: 9358: 9353: 9348: 9341: 9335: 9331: 9326: 9321: 9314: 9308: 9304: 9298: 9293: 9270: 9265: 9258: 9252: 9248: 9245: 9242: 9236: 9230: 9226: 9203: 9198: 9191: 9185: 9181: 9178: 9175: 9169: 9163: 9159: 9138: 9135: 9130: 9125: 9118: 9112: 9091: 9088: 9083: 9078: 9071: 9065: 9042: 9019: 9018: 9017: 9016: 8999: 8998: 8997: 8987: 8984: 8970: 8967: 8949: 8944: 8943: 8942: 8932: 8926: 8923: 8909: 8906: 8888: 8882: 8829: 8826: 8822:Beth's theorem 8807: 8802: 8787:is said to be 8776: 8756: 8753: 8750: 8745: 8721: 8699: 8679: 8676: 8654: 8632: 8612: 8607: 8585: 8576:itself, since 8565: 8545: 8523: 8501: 8481: 8459: 8456: 8453: 8448: 8444: 8440: 8437: 8434: 8429: 8425: 8421: 8418: 8415: 8410: 8405: 8400: 8396: 8392: 8389: 8384: 8380: 8376: 8373: 8370: 8365: 8361: 8357: 8354: 8351: 8348: 8328: 8323: 8319: 8315: 8312: 8309: 8304: 8300: 8296: 8293: 8271: 8249: 8229: 8220:-ary relation 8209: 8197: 8194: 8158: 8155: 8135: 8113: 8091: 8066: 8060: 8054: 8040:is said to be 8029: 8017: 8014: 8002: 7999: 7996: 7993: 7990: 7987: 7984: 7981: 7978: 7975: 7972: 7969: 7966: 7963: 7958: 7936: 7933: 7930: 7927: 7905: 7883: 7863: 7840: 7835: 7831: 7827: 7824: 7821: 7816: 7812: 7808: 7805: 7802: 7797: 7792: 7789: 7786: 7783: 7778: 7774: 7770: 7767: 7764: 7759: 7755: 7751: 7731: 7711: 7691: 7688: 7685: 7680: 7676: 7672: 7669: 7666: 7661: 7657: 7653: 7650: 7647: 7642: 7637: 7632: 7628: 7624: 7621: 7616: 7612: 7608: 7605: 7602: 7597: 7593: 7589: 7586: 7583: 7580: 7560: 7555: 7551: 7547: 7544: 7541: 7536: 7532: 7528: 7525: 7504: 7478: 7457:is said to be 7444: 7422: 7402: 7393:-ary relation 7382: 7370: 7367: 7363:ZFC set theory 7350: 7345: 7323: 7303: 7281: 7259: 7230: 7201: 7198: 7176: 7154: 7133: 7130: 7125: 7100: 7097: 7094: 7091: 7088: 7085: 7082: 7079: 7074: 7060: 7057: 7033: 7030: 6994: 6993: 6979: 6974: 6969: 6964: 6961: 6939: 6915: 6893: 6890: 6845: 6842: 6785: 6761: 6732: 6727: 6703: 6698: 6686: 6685: 6684: 6683: 6669: 6664: 6660: 6657: 6654: 6649: 6645: 6641: 6638: 6635: 6632: 6629: 6626: 6621: 6617: 6613: 6610: 6607: 6604: 6599: 6595: 6591: 6588: 6585: 6581: 6574: 6569: 6565: 6562: 6557: 6553: 6549: 6546: 6543: 6538: 6534: 6530: 6525: 6521: 6517: 6504: 6503: 6489: 6485: 6481: 6478: 6475: 6470: 6466: 6462: 6457: 6453: 6410: 6405: 6400: 6395: 6392: 6380: 6377: 6369: 6368: 6357: 6354: 6349: 6345: 6341: 6338: 6335: 6330: 6326: 6321: 6318: 6314: 6311: 6306: 6302: 6298: 6295: 6292: 6287: 6283: 6278: 6275: 6270: 6266: 6262: 6259: 6256: 6251: 6247: 6223: 6218: 6214: 6211: 6206: 6202: 6198: 6195: 6192: 6187: 6183: 6179: 6174: 6170: 6166: 6145: 6139: 6133: 6129: 6124: 6120: 6116: 6113: 6110: 6105: 6101: 6097: 6092: 6088: 6064: 6059: 6055: 6052: 6047: 6043: 6039: 6036: 6033: 6028: 6024: 6020: 6015: 6011: 6007: 5986: 5980: 5974: 5970: 5965: 5961: 5957: 5954: 5951: 5946: 5942: 5938: 5933: 5929: 5890: 5885: 5880: 5875: 5872: 5829: 5805: 5782: 5776: 5770: 5748: 5742: 5736: 5709: 5704: 5699: 5694: 5691: 5669: 5645: 5627:respectively. 5614: 5590: 5568: 5545: 5540: 5516: 5511: 5499: 5498: 5497: 5496: 5482: 5477: 5473: 5470: 5467: 5462: 5458: 5454: 5451: 5448: 5445: 5442: 5439: 5434: 5430: 5426: 5423: 5420: 5417: 5412: 5408: 5404: 5401: 5398: 5394: 5387: 5382: 5378: 5375: 5370: 5366: 5362: 5359: 5356: 5351: 5347: 5343: 5338: 5334: 5330: 5317: 5316: 5303: 5297: 5291: 5287: 5282: 5278: 5274: 5271: 5268: 5263: 5259: 5255: 5250: 5246: 5225: 5224: 5223: 5222: 5210: 5207: 5202: 5198: 5194: 5191: 5188: 5185: 5182: 5179: 5174: 5170: 5166: 5163: 5160: 5157: 5152: 5148: 5144: 5141: 5138: 5135: 5132: 5129: 5126: 5121: 5117: 5113: 5110: 5107: 5102: 5098: 5094: 5089: 5085: 5081: 5078: 5075: 5072: 5059: 5058: 5045: 5039: 5033: 5029: 5024: 5020: 5016: 5013: 5010: 5005: 5001: 4997: 4992: 4988: 4954: 4948: 4942: 4938: 4934: 4928: 4922: 4918: 4915: 4890: 4866: 4838: 4814: 4800: 4797: 4789: 4786: 4765: 4762: 4742: 4722: 4702: 4678: 4658: 4633: 4629: 4626: 4623: 4620: 4617: 4598: 4595: 4575: 4555: 4552: 4532: 4481: 4461: 4458: 4455: 4452: 4449: 4446: 4443: 4440: 4437: 4434: 4431: 4428: 4425: 4413: 4410: 4382: 4377: 4355: 4334: 4331: 4310: 4305: 4283: 4279: 4276: 4272: 4269: 4266: 4263: 4260: 4240: 4237: 4234: 4214: 4211: 4208: 4205: 4202: 4199: 4196: 4193: 4188: 4162: 4156: 4150: 4138:set of subsets 4121: 4118: 4095: 4090: 4086: 4083: 4063: 4060: 4057: 4037: 4034: 4010: 4007: 3983: 3980: 3971:that contains 3959: 3953: 3947: 3925: 3919: 3913: 3909: 3906: 3884: 3881: 3878: 3875: 3870: 3866: 3862: 3859: 3856: 3851: 3847: 3843: 3838: 3834: 3830: 3827: 3808: 3805: 3783: 3779: 3775: 3770: 3766: 3760: 3756: 3735: 3715: 3695: 3692: 3689: 3684: 3680: 3676: 3673: 3670: 3665: 3661: 3657: 3652: 3648: 3625: 3603: 3583: 3563: 3560: 3540: 3535: 3507: 3484: 3478: 3472: 3468: 3465: 3443: 3438: 3433: 3428: 3415: 3414: 3403: 3399: 3393: 3387: 3375: 3363: 3359: 3353: 3347: 3343: 3339: 3333: 3327: 3307: 3302: 3278: 3267:the domain of 3265: 3254: 3251: 3246: 3241: 3238: 3235: 3232: 3227: 3222: 3219: 3197: 3173: 3146: 3118: 3105: 3102: 3089: 3069: 3066: 3038: 3035: 3013: 3001:ordered fields 2983: 2979: 2968: 2952: 2948: 2922: 2895: 2890: 2866: 2861: 2849: 2848: 2837: 2834: 2825:is the number 2813: 2809: 2806: 2803: 2800: 2794: 2789: 2778: 2766: 2763: 2754:is the number 2742: 2738: 2735: 2732: 2729: 2723: 2718: 2707: 2695: 2692: 2689: 2669: 2648: 2644: 2640: 2636: 2633: 2630: 2627: 2621: 2616: 2605: 2592: 2588: 2584: 2580: 2576: 2572: 2569: 2566: 2563: 2557: 2552: 2541: 2528: 2524: 2520: 2516: 2512: 2508: 2505: 2502: 2499: 2493: 2488: 2461: 2456: 2429: 2426: 2423: 2421: 2418: 2415: 2412: 2409: 2407: 2403: 2399: 2395: 2394: 2391: 2388: 2385: 2382: 2380: 2377: 2374: 2371: 2368: 2366: 2362: 2358: 2354: 2353: 2350: 2347: 2344: 2341: 2339: 2336: 2333: 2330: 2327: 2325: 2321: 2317: 2313: 2312: 2309: 2306: 2303: 2300: 2298: 2295: 2292: 2289: 2286: 2284: 2280: 2276: 2272: 2271: 2268: 2265: 2262: 2259: 2257: 2254: 2251: 2248: 2245: 2243: 2239: 2235: 2231: 2230: 2210: 2207: 2204: 2201: 2198: 2195: 2192: 2189: 2186: 2183: 2180: 2177: 2172: 2168: 2147: 2142: 2138: 2134: 2129: 2125: 2121: 2118: 2113: 2109: 2082: 2076: 2071: 2067: 2062: 2058: 2054: 2050: 2046: 2043: 2040: 2038: 2034: 2029: 2028: 2025: 2019: 2014: 2010: 2005: 2001: 1997: 1993: 1989: 1986: 1983: 1981: 1977: 1972: 1971: 1968: 1962: 1957: 1953: 1948: 1944: 1940: 1936: 1932: 1929: 1926: 1924: 1920: 1915: 1914: 1894: 1874: 1870: 1845: 1821: 1817: 1793: 1772: 1750: 1728: 1706: 1684: 1662: 1640: 1618: 1591: 1587: 1574: 1571: 1559: 1555: 1549: 1543: 1539: 1534: 1529: 1522: 1516: 1512: 1506: 1501: 1478: 1473: 1468: 1462: 1456: 1453: 1433: 1428: 1406: 1386: 1383: 1380: 1377: 1374: 1354: 1331: 1328: 1325: 1322: 1296: 1276: 1272: 1249: 1246: 1243: 1240: 1237: 1232: 1228: 1225: 1222: 1219: 1216: 1213: 1207: 1202: 1192:-ary relation 1181: 1161: 1141: 1121: 1118: 1115: 1112: 1109: 1103: 1098: 1075: 1054: 1034: 1012: 990: 968: 965: 932: 929: 905: 892:is called the 881: 861: 858: 855: 852: 849: 846: 843: 833:natural number 829: 828: 817: 814: 811: 808: 805: 802: 799: 796: 786:natural number 773: 751: 746: 741: 738: 732: 729: 718: 694: 670: 667: 664: 661: 658: 655: 652: 643:The signature 637:Main article: 634: 631: 616: 594: 589: 566: 560: 554: 533: 528: 523: 520: 517: 500: 490: 486: 482: 481:underlying set 473:Main article: 470: 467: 454: 434: 414: 391: 388: 365: 362: 337: 334: 331: 328: 325: 322: 319: 316: 311: 293: 290: 268: 267: 247: 245: 234: 231: 199:semantic model 111:consists of a 95: 94: 49: 47: 40: 26: 9: 6: 4: 3: 2: 12125: 12114: 12111: 12109: 12106: 12104: 12101: 12099: 12096: 12095: 12093: 12080: 12079: 12074: 12066: 12060: 12057: 12055: 12052: 12050: 12047: 12045: 12042: 12038: 12035: 12034: 12033: 12030: 12028: 12025: 12023: 12020: 12018: 12014: 12011: 12009: 12006: 12004: 12001: 11999: 11996: 11994: 11991: 11990: 11988: 11984: 11978: 11975: 11973: 11970: 11968: 11967:Recursive set 11965: 11963: 11960: 11958: 11955: 11953: 11950: 11948: 11945: 11941: 11938: 11936: 11933: 11931: 11928: 11926: 11923: 11921: 11918: 11917: 11916: 11913: 11911: 11908: 11906: 11903: 11901: 11898: 11896: 11893: 11891: 11888: 11887: 11885: 11883: 11879: 11873: 11870: 11868: 11865: 11863: 11860: 11858: 11855: 11853: 11850: 11848: 11845: 11843: 11840: 11836: 11833: 11831: 11828: 11826: 11823: 11822: 11821: 11818: 11816: 11813: 11811: 11808: 11806: 11803: 11801: 11798: 11796: 11793: 11789: 11786: 11785: 11784: 11781: 11777: 11776:of arithmetic 11774: 11773: 11772: 11769: 11765: 11762: 11760: 11757: 11755: 11752: 11750: 11747: 11745: 11742: 11741: 11740: 11737: 11733: 11730: 11728: 11725: 11724: 11723: 11720: 11719: 11717: 11715: 11711: 11705: 11702: 11700: 11697: 11695: 11692: 11690: 11687: 11684: 11683:from ZFC 11680: 11677: 11675: 11672: 11666: 11663: 11662: 11661: 11658: 11656: 11653: 11651: 11648: 11647: 11646: 11643: 11641: 11638: 11636: 11633: 11631: 11628: 11626: 11623: 11621: 11618: 11616: 11613: 11612: 11610: 11608: 11604: 11594: 11593: 11589: 11588: 11583: 11582:non-Euclidean 11580: 11576: 11573: 11571: 11568: 11566: 11565: 11561: 11560: 11558: 11555: 11554: 11552: 11548: 11544: 11541: 11539: 11536: 11535: 11534: 11530: 11526: 11523: 11522: 11521: 11517: 11513: 11510: 11508: 11505: 11503: 11500: 11498: 11495: 11493: 11490: 11488: 11485: 11484: 11482: 11478: 11477: 11475: 11470: 11464: 11459:Example  11456: 11448: 11443: 11442: 11441: 11438: 11436: 11433: 11429: 11426: 11424: 11421: 11419: 11416: 11414: 11411: 11410: 11409: 11406: 11404: 11401: 11399: 11396: 11394: 11391: 11387: 11384: 11382: 11379: 11378: 11377: 11374: 11370: 11367: 11365: 11362: 11360: 11357: 11355: 11352: 11351: 11350: 11347: 11345: 11342: 11338: 11335: 11333: 11330: 11328: 11325: 11324: 11323: 11320: 11316: 11313: 11311: 11308: 11306: 11303: 11301: 11298: 11296: 11293: 11291: 11288: 11287: 11286: 11283: 11281: 11278: 11276: 11273: 11271: 11268: 11264: 11261: 11259: 11256: 11254: 11251: 11249: 11246: 11245: 11244: 11241: 11239: 11236: 11234: 11231: 11229: 11226: 11222: 11219: 11217: 11216:by definition 11214: 11213: 11212: 11209: 11205: 11202: 11201: 11200: 11197: 11195: 11192: 11190: 11187: 11185: 11182: 11180: 11177: 11176: 11173: 11170: 11168: 11164: 11159: 11153: 11149: 11139: 11136: 11134: 11131: 11129: 11126: 11124: 11121: 11119: 11116: 11114: 11111: 11109: 11106: 11104: 11103:Kripke–Platek 11101: 11099: 11096: 11092: 11089: 11087: 11084: 11083: 11082: 11079: 11078: 11076: 11072: 11064: 11061: 11060: 11059: 11056: 11054: 11051: 11047: 11044: 11043: 11042: 11039: 11037: 11034: 11032: 11029: 11027: 11024: 11022: 11019: 11016: 11012: 11008: 11005: 11001: 10998: 10996: 10993: 10991: 10988: 10987: 10986: 10982: 10979: 10978: 10976: 10974: 10970: 10966: 10958: 10955: 10953: 10950: 10948: 10947:constructible 10945: 10944: 10943: 10940: 10938: 10935: 10933: 10930: 10928: 10925: 10923: 10920: 10918: 10915: 10913: 10910: 10908: 10905: 10903: 10900: 10898: 10895: 10893: 10890: 10888: 10885: 10883: 10880: 10879: 10877: 10875: 10870: 10862: 10859: 10857: 10854: 10852: 10849: 10847: 10844: 10842: 10839: 10837: 10834: 10833: 10831: 10827: 10824: 10822: 10819: 10818: 10817: 10814: 10812: 10809: 10807: 10804: 10802: 10799: 10797: 10793: 10789: 10787: 10784: 10780: 10777: 10776: 10775: 10772: 10771: 10768: 10765: 10763: 10759: 10749: 10746: 10744: 10741: 10739: 10736: 10734: 10731: 10729: 10726: 10724: 10721: 10717: 10714: 10713: 10712: 10709: 10705: 10700: 10699: 10698: 10695: 10694: 10692: 10690: 10686: 10678: 10675: 10673: 10670: 10668: 10665: 10664: 10663: 10660: 10658: 10655: 10653: 10650: 10648: 10645: 10643: 10640: 10638: 10635: 10633: 10630: 10629: 10627: 10625: 10624:Propositional 10621: 10615: 10612: 10610: 10607: 10605: 10602: 10600: 10597: 10595: 10592: 10590: 10587: 10583: 10580: 10579: 10578: 10575: 10573: 10570: 10568: 10565: 10563: 10560: 10558: 10555: 10553: 10552:Logical truth 10550: 10548: 10545: 10544: 10542: 10540: 10536: 10533: 10531: 10527: 10521: 10518: 10516: 10513: 10511: 10508: 10506: 10503: 10501: 10498: 10496: 10492: 10488: 10484: 10482: 10479: 10477: 10474: 10472: 10468: 10465: 10464: 10462: 10460: 10454: 10449: 10443: 10440: 10438: 10435: 10433: 10430: 10428: 10425: 10423: 10420: 10418: 10415: 10413: 10410: 10408: 10405: 10403: 10400: 10398: 10395: 10393: 10390: 10388: 10385: 10381: 10378: 10377: 10376: 10373: 10372: 10370: 10366: 10362: 10355: 10350: 10348: 10343: 10341: 10336: 10335: 10332: 10325: 10322:(an entry of 10321: 10317: 10314: 10313: 10304: 10298: 10294: 10290: 10285: 10282: 10276: 10272: 10268: 10264: 10260: 10256: 10252: 10248: 10245: 10239: 10235: 10230: 10229: 10222: 10219: 10213: 10209: 10205: 10200: 10197: 10191: 10187: 10184:, Cambridge: 10183: 10179: 10175: 10172: 10166: 10162: 10159:, Cambridge: 10157: 10156: 10150: 10146: 10143: 10137: 10133: 10129: 10124: 10121: 10115: 10110: 10109: 10102: 10099: 10093: 10089: 10085: 10084: 10078: 10075: 10069: 10065: 10061: 10056: 10053: 10049: 10048: 10042: 10041: 10029: 10027:9780080528700 10023: 10019: 10018: 10010: 10002: 9998: 9994: 9990: 9986: 9982: 9975: 9957: 9944: 9926: 9922: 9901: 9881: 9878: 9875: 9872: 9869: 9866: 9847: 9842: 9838: 9795: 9787: 9772: 9770: 9750: 9735: 9695: 9688: 9682: 9674: 9667: 9661: 9658: 9654: 9648: 9640: 9634: 9630: 9623: 9616: 9610: 9606: 9595: 9592: 9591: 9585: 9583: 9582: 9577: 9572: 9570: 9566: 9562: 9558: 9548: 9546: 9542: 9536: 9526: 9524: 9520: 9510: 9506: 9504: 9500: 9496: 9493: +  9492: 9489: =  9488: 9485: +  9484: 9480: 9457: 9421: 9419: 9415: 9411: 9407: 9403: 9398: 9394: 9378: 9351: 9329: 9324: 9302: 9291: 9268: 9246: 9243: 9240: 9228: 9224: 9201: 9179: 9176: 9173: 9161: 9157: 9136: 9133: 9128: 9089: 9086: 9081: 9030: 9026: 9014: 9010: 9006: 9002: 9001: 9000: 8995: 8990: 8985: 8982: 8978: 8973: 8968: 8965: 8961: 8957: 8952: 8947: 8946: 8945: 8940: 8935: 8929: 8924: 8921: 8917: 8912: 8907: 8904: 8900: 8896: 8891: 8885: 8880: 8879: 8878: 8874: 8872: 8868: 8864: 8863:Vector spaces 8860: 8857: 8853: 8849: 8840: 8825: 8823: 8818: 8805: 8790: 8774: 8754: 8751: 8748: 8697: 8677: 8674: 8630: 8610: 8583: 8563: 8543: 8499: 8479: 8470: 8457: 8446: 8442: 8438: 8435: 8432: 8427: 8423: 8416: 8413: 8403: 8398: 8394: 8390: 8382: 8378: 8374: 8371: 8368: 8363: 8359: 8349: 8346: 8321: 8317: 8313: 8310: 8307: 8302: 8298: 8291: 8247: 8227: 8207: 8193: 8191: 8187: 8183: 8179: 8175: 8170: 8156: 8153: 8133: 8089: 8081: 8043: 8027: 8013: 8000: 7991: 7985: 7979: 7976: 7973: 7967: 7961: 7931: 7925: 7881: 7861: 7852: 7833: 7829: 7825: 7822: 7819: 7814: 7810: 7803: 7800: 7787: 7784: 7776: 7772: 7768: 7765: 7762: 7757: 7753: 7729: 7709: 7689: 7678: 7674: 7670: 7667: 7664: 7659: 7655: 7648: 7645: 7635: 7630: 7626: 7622: 7614: 7610: 7606: 7603: 7600: 7595: 7591: 7581: 7578: 7553: 7549: 7545: 7542: 7539: 7534: 7530: 7523: 7515: 7492: 7468: 7464: 7460: 7420: 7400: 7380: 7366: 7364: 7348: 7321: 7301: 7257: 7250: 7246: 7217: 7215: 7199: 7196: 7152: 7131: 7128: 7114: 7095: 7092: 7089: 7086: 7083: 7077: 7056: 7054: 7050: 7043: 7039: 7029: 7026: 7022: 7018: 7014: 7009: 7007: 7003: 6999: 6962: 6959: 6903: 6902: 6901: 6899: 6889: 6887: 6883: 6879: 6875: 6871: 6867: 6864: →  6863: 6859: 6855: 6851: 6841: 6839: 6835: 6831: 6830:monomorphisms 6827: 6823: 6819: 6814: 6812: 6808: 6804: 6799: 6749: 6725: 6696: 6662: 6658: 6647: 6643: 6636: 6633: 6630: 6627: 6619: 6615: 6608: 6605: 6597: 6593: 6586: 6567: 6563: 6555: 6551: 6547: 6544: 6541: 6536: 6532: 6528: 6523: 6519: 6508: 6507: 6506: 6505: 6487: 6483: 6479: 6476: 6473: 6468: 6464: 6460: 6455: 6451: 6442: 6438: 6434: 6433: 6432: 6430: 6426: 6393: 6390: 6376: 6374: 6355: 6347: 6343: 6336: 6333: 6328: 6324: 6319: 6316: 6312: 6304: 6300: 6293: 6290: 6285: 6281: 6276: 6268: 6264: 6257: 6254: 6249: 6245: 6216: 6212: 6204: 6200: 6196: 6193: 6190: 6185: 6181: 6177: 6172: 6168: 6127: 6122: 6118: 6114: 6111: 6108: 6103: 6099: 6095: 6090: 6086: 6057: 6053: 6045: 6041: 6037: 6034: 6031: 6026: 6022: 6018: 6013: 6009: 5968: 5963: 5959: 5955: 5952: 5949: 5944: 5940: 5936: 5931: 5927: 5918: 5914: 5910: 5909: 5908: 5906: 5873: 5870: 5861: 5859: 5855: 5851: 5848: 5843: 5725: 5692: 5689: 5633: 5628: 5566: 5538: 5509: 5475: 5471: 5460: 5456: 5449: 5446: 5443: 5440: 5432: 5428: 5421: 5418: 5410: 5406: 5399: 5380: 5376: 5368: 5364: 5360: 5357: 5354: 5349: 5345: 5341: 5336: 5332: 5321: 5320: 5319: 5318: 5285: 5280: 5276: 5272: 5269: 5266: 5261: 5257: 5253: 5248: 5244: 5235: 5231: 5227: 5226: 5200: 5196: 5189: 5186: 5183: 5180: 5172: 5168: 5161: 5158: 5150: 5146: 5139: 5133: 5130: 5119: 5115: 5111: 5108: 5105: 5100: 5096: 5092: 5087: 5083: 5076: 5070: 5063: 5062: 5061: 5060: 5027: 5022: 5018: 5014: 5011: 5008: 5003: 4999: 4995: 4990: 4986: 4977: 4973: 4969: 4968: 4967: 4916: 4913: 4906: 4854: 4799:Homomorphisms 4795: 4785: 4783: 4779: 4763: 4760: 4740: 4720: 4700: 4692: 4676: 4656: 4631: 4624: 4621: 4618: 4596: 4593: 4573: 4553: 4550: 4530: 4522: 4517: 4515: 4511: 4505: 4503: 4499: 4495: 4479: 4456: 4453: 4450: 4447: 4444: 4441: 4438: 4435: 4432: 4426: 4423: 4409: 4407: 4403: 4399: 4394: 4380: 4353: 4332: 4329: 4308: 4277: 4274: 4270: 4267: 4264: 4261: 4238: 4235: 4232: 4209: 4206: 4203: 4200: 4197: 4191: 4175: 4139: 4135: 4084: 4058: 4035: 4032: 4024: 4008: 4005: 3997: 3981: 3978: 3907: 3904: 3895: 3882: 3879: 3876: 3868: 3864: 3860: 3857: 3854: 3849: 3845: 3841: 3836: 3832: 3825: 3806: 3803: 3781: 3777: 3773: 3768: 3764: 3758: 3754: 3733: 3713: 3693: 3690: 3687: 3682: 3678: 3674: 3671: 3668: 3663: 3659: 3655: 3650: 3646: 3601: 3581: 3561: 3558: 3538: 3523: 3466: 3463: 3454: 3441: 3431: 3401: 3376: 3361: 3341: 3305: 3266: 3252: 3236: 3233: 3217: 3162: 3161: 3160: 3134: 3131:is called an 3101: 3087: 3067: 3064: 3055: 3053: 3036: 3033: 3011: 3002: 2997: 2981: 2977: 2966: 2950: 2946: 2937: 2912:But the ring 2910: 2888: 2859: 2835: 2832: 2807: 2801: 2787: 2779: 2764: 2761: 2736: 2730: 2716: 2708: 2693: 2690: 2687: 2667: 2634: 2628: 2614: 2606: 2578: 2570: 2564: 2550: 2542: 2514: 2506: 2500: 2486: 2478: 2477: 2476: 2454: 2444: 2427: 2424: 2422: 2413: 2408: 2401: 2397: 2389: 2386: 2383: 2381: 2372: 2367: 2360: 2356: 2348: 2345: 2342: 2340: 2331: 2326: 2319: 2315: 2307: 2304: 2301: 2299: 2290: 2285: 2278: 2274: 2266: 2263: 2260: 2258: 2249: 2244: 2237: 2233: 2205: 2202: 2199: 2196: 2193: 2190: 2187: 2184: 2181: 2175: 2170: 2166: 2140: 2136: 2132: 2127: 2123: 2116: 2111: 2107: 2097: 2069: 2065: 2060: 2056: 2052: 2041: 2039: 2012: 2008: 2003: 1999: 1995: 1984: 1982: 1955: 1951: 1946: 1942: 1938: 1927: 1925: 1892: 1872: 1860: 1835: 1819: 1807: 1791: 1770: 1638: 1607: 1589: 1585: 1570: 1557: 1532: 1510: 1499: 1466: 1454: 1451: 1431: 1404: 1384: 1378: 1372: 1352: 1343: 1326: 1320: 1312: 1311: 1294: 1274: 1270: 1230: 1226: 1220: 1214: 1211: 1200: 1179: 1159: 1139: 1116: 1110: 1107: 1096: 1087: 1073: 1052: 1032: 988: 981: 974: 964: 962: 958: 954: 953: 948: 943: 930: 927: 919: 903: 895: 879: 856: 850: 847: 844: 841: 834: 815: 809: 803: 800: 797: 794: 787: 771: 749: 736: 730: 727: 719: 716: 715: 710: 709: 692: 684: 683: 682: 665: 662: 659: 653: 650: 640: 630: 592: 518: 515: 506: 504: 499: 496: 494: 488: 484: 480: 476: 466: 452: 432: 412: 405: 389: 386: 379: 363: 360: 353: 352: 332: 329: 326: 323: 320: 314: 299: 289: 287: 283: 279: 275: 264: 261:November 2023 255: 251: 248:This section 246: 243: 239: 238: 230: 228: 224: 220: 215: 213: 209: 205: 201: 200: 195: 190: 188: 184: 180: 175: 173: 169: 165: 161: 157: 153: 149: 145: 144:vector spaces 141: 137: 133: 129: 124: 122: 118: 114: 110: 106: 102: 91: 88: 80: 70: 66: 60: 59: 53: 48: 39: 38: 33: 19: 12108:Model theory 12069: 11867:Ultraproduct 11738: 11714:Model theory 11679:Independence 11615:Formal proof 11607:Proof theory 11590: 11563: 11520:real numbers 11492:second-order 11403:Substitution 11280:Metalanguage 11221:conservative 11194:Axiom schema 11138:Constructive 11108:Morse–Kelley 11074:Set theories 11053:Aleph number 11046:inaccessible 10952:Grothendieck 10836:intersection 10723:Higher-order 10711:Second-order 10657:Truth tables 10614:Venn diagram 10426: 10397:Formal proof 10288: 10254: 10227: 10203: 10181: 10155:Model theory 10154: 10127: 10107: 10083:Graph Theory 10082: 10066:, Elsevier, 10064:Model Theory 10063: 10046: 10016: 10009: 9984: 9980: 9974: 9942: 9694: 9681: 9672: 9666: 9656: 9652: 9647: 9628: 9622: 9609: 9579: 9573: 9569:class models 9568: 9565:proper class 9554: 9538: 9522: 9516: 9507: 9494: 9490: 9486: 9482: 9478: 9455: 9432: 9399: 9395: 9028: 9024: 9022: 9012: 9008: 9004: 9003:× of arity ( 8993: 8988: 8980: 8976: 8971: 8963: 8959: 8955: 8950: 8938: 8933: 8927: 8919: 8915: 8910: 8902: 8898: 8894: 8889: 8883: 8870: 8866: 8861: 8851: 8842: 8833: 8831: 8819: 8788: 8471: 8199: 8189: 8185: 8181: 8177: 8173: 8171: 8079: 8041: 8019: 7853: 7851:is correct. 7494: 7490: 7462: 7458: 7372: 7244: 7219:A structure 7218: 7112: 7062: 7052: 7045: 7010: 6995: 6897: 6895: 6885: 6877: 6873: 6870:monomorphism 6865: 6861: 6857: 6853: 6847: 6837: 6833: 6825: 6821: 6815: 6810: 6802: 6800: 6747: 6687: 6440: 6436: 6424: 6382: 6372: 6370: 6078:, there are 5916: 5912: 5904: 5862: 5853: 5844: 5723: 5631: 5629: 5500: 5233: 5229: 4975: 4971: 4852: 4802: 4778:graph theory 4518: 4506: 4498:real numbers 4415: 4395: 4176: 4022: 3995: 3896: 3521: 3455: 3416: 3107: 3056: 2998: 2996:-structure. 2911: 2850: 2445: 2098: 1834:real numbers 1576: 1491:rather than 1344: 1308: 1307:is called a 979: 977: 956: 950: 944: 893: 872:of a symbol 830: 717:, along with 712: 706: 642: 507: 503:empty domain 478: 465:-structure. 403: 349: 297: 296:Formally, a 295: 271: 258: 254:adding to it 249: 216: 197: 193: 191: 176: 168:foundational 166:, including 160:Model theory 147: 125: 108: 105:model theory 98: 83: 74: 55: 11977:Type theory 11925:undecidable 11857:Truth value 11744:equivalence 11423:non-logical 11036:Enumeration 11026:Isomorphism 10973:cardinality 10957:Von Neumann 10922:Ultrafilter 10887:Uncountable 10821:equivalence 10738:Quantifiers 10728:Fixed-point 10697:First-order 10577:Consistency 10562:Proposition 10539:Traditional 10510:Lindström's 10500:Compactness 10442:Type theory 10387:Cardinality 10318:section in 9734:cardinality 9519:type theory 9410:Bart Jacobs 9406:type theory 8020:A relation 6807:subcategory 4649:means that 720:a function 181:, cf. also 146:. The term 69:introducing 12092:Categories 11788:elementary 11481:arithmetic 11349:Quantifier 11327:functional 11199:Expression 10917:Transitive 10861:identities 10846:complement 10779:hereditary 10762:Set theory 10291:, London: 10132:A K Peters 10038:References 9557:set theory 8992:of arity ( 8975:of arity ( 8954:of arity ( 8937:of arity ( 8914:of arity ( 8893:of arity ( 8734:such that 8339:such that 8126:such that 7947:such that 7742:such that 7571:such that 7036:See also: 7015:, where a 6818:subobjects 6435:for every 6429:one-to-one 6379:Embeddings 6157:such that 5998:such that 5911:For every 5228:For every 4970:For every 4792:See also: 3520:is called 495:), or its 292:Definition 286:set theory 172:set theory 77:April 2010 52:references 12059:Supertask 11962:Recursion 11920:decidable 11754:saturated 11732:of models 11655:deductive 11650:axiomatic 11570:Hilbert's 11557:Euclidean 11538:canonical 11461:axiomatic 11393:Signature 11322:Predicate 11211:Extension 11133:Ackermann 11058:Operation 10937:Universal 10927:Recursive 10902:Singleton 10897:Inhabited 10882:Countable 10872:Types of 10856:power set 10826:partition 10743:Predicate 10689:Predicate 10604:Syllogism 10594:Soundness 10567:Inference 10557:Tautology 10459:paradoxes 10316:Semantics 10293:CRC Press 10062:(1989) , 9987:: 51–67, 9902:− 9817:− 9615:relations 9466:∀ 9442:∀ 9357:→ 9330:× 9292:× 9247:∈ 9180:∈ 8752:φ 8749:⊨ 8631:φ 8544:φ 8480:φ 8436:… 8417:φ 8414:⊨ 8391:∈ 8372:… 8311:… 8292:φ 8186:definable 8174:definable 8154:φ 8090:φ 8080:definable 7986:φ 7983:↔ 7965:∀ 7962:⊨ 7926:φ 7823:… 7804:φ 7801:⊨ 7791:⇔ 7785:∈ 7766:… 7730:φ 7668:… 7649:φ 7646:⊨ 7623:∈ 7604:… 7543:… 7524:φ 7503:∅ 7491:definable 7477:∅ 7459:definable 7153:ϕ 7132:ϕ 7129:⊨ 7090:σ 6973:→ 6882:subobject 6659:∈ 6631:… 6580:⟺ 6564:∈ 6545:… 6477:… 6427:if it is 6425:embedding 6404:→ 6317:… 6213:∈ 6194:… 6128:∈ 6112:… 6054:∈ 6035:… 5969:∈ 5953:… 5884:→ 5858:morphisms 5703:→ 5472:∈ 5444:… 5393:⟹ 5377:∈ 5358:… 5286:∈ 5270:… 5184:… 5109:… 5028:∈ 5012:… 4937:→ 4632:∈ 4531:σ 4480:σ 4445:− 4439:× 4424:σ 4268:σ 4236:⊆ 4204:σ 4120:⟩ 4117:⟨ 4089:⟩ 4082:⟨ 4062:⟩ 4056:⟨ 3996:generated 3908:⊆ 3877:∈ 3858:… 3774:… 3688:∈ 3672:… 3467:⊆ 3456:A subset 3432:⊆ 3342:⊆ 3237:σ 3218:σ 3088:∈ 3065:∈ 3034:≤ 2978:σ 2947:σ 2808:∈ 2737:∈ 2688:− 2643:→ 2629:− 2587:→ 2579:× 2565:× 2523:→ 2515:× 2332:− 2291:× 2194:− 2188:× 2108:σ 2057:σ 2000:σ 1943:σ 1893:σ 1771:× 1661:− 1639:× 1586:σ 1538:→ 1472:→ 1227:⊆ 1152:of arity 1088:function 1045:of arity 851:⁡ 804:⁡ 740:→ 651:σ 633:Signature 519:⁡ 453:σ 433:σ 387:σ 378:signature 327:σ 298:structure 223:databases 121:relations 109:structure 12044:Logicism 12037:timeline 12013:Concrete 11872:Validity 11842:T-schema 11835:Kripke's 11830:Tarski's 11825:semantic 11815:Strength 11764:submodel 11759:spectrum 11727:function 11575:Tarski's 11564:Elements 11551:geometry 11507:Robinson 11428:variable 11413:function 11386:spectrum 11376:Sentence 11332:variable 11275:Language 11228:Relation 11189:Automata 11179:Alphabet 11163:language 11017:-jection 10995:codomain 10981:Function 10942:Universe 10912:Infinite 10816:Relation 10599:Validity 10589:Argument 10487:theorem, 10259:New York 10253:(2010), 10180:(1997), 10151:(1993), 10001:15244028 9588:See also 8176:to mean 7214:T-schema 7021:database 5850:category 5847:concrete 4691:subgraph 4514:subfield 4412:Examples 4333:′ 4278:′ 2936:integers 1857:and the 1573:Examples 493:universe 489:universe 154:with no 130:such as 11986:Related 11783:Diagram 11681: ( 11660:Hilbert 11645:Systems 11640:Theorem 11518:of the 11463:systems 11243:Formula 11238:Grammar 11154: ( 11098:General 10811:Forcing 10796:Element 10716:Monadic 10491:paradox 10432:Theorem 10368:General 9503:variety 9481: ( 9011:;  9007:,  8979:;  8962:;  8958:,  8918:;  8901:;  8897:,  8536:and so 6844:Example 4510:subring 4398:lattice 4136:on the 4021:or the 3746:-tuple 3726:to the 957:algebra 947:algebra 485:carrier 402:and an 233:History 103:and in 65:improve 11749:finite 11512:Skolem 11465:  11440:Theory 11408:Symbol 11398:String 11381:atomic 11258:ground 11253:closed 11248:atomic 11204:ground 11167:syntax 11063:binary 10990:domain 10907:Finite 10672:finite 10530:Logics 10489:  10437:Theory 10299:  10277:  10240:  10214:  10192:  10167:  10138:  10116:  10094:  10070:  10024:  9999:  9775:Note: 9635:  9458:  9454:  9418:fibred 8188:means 7249:theory 7111:has a 7053:models 7040:, and 6996:Every 5905:strong 5501:where 4400:. The 4321:where 3574:every 3522:closed 1606:fields 734:  685:a set 469:Domain 351:domain 140:fields 132:groups 54:, but 11739:Model 11487:Peano 11344:Proof 11184:Arity 11113:Naive 11000:image 10932:Fuzzy 10892:Empty 10841:union 10786:Class 10427:Model 10417:Lemma 10375:Axiom 9997:S2CID 9943:minus 9601:Notes 9408:. As 8931:and 1 8887:and × 8852:sorts 8791:over 8767:then 7493:, or 7469:, or 7247:of a 7245:model 7019:of a 6880:is a 6832:of σ- 6820:in σ- 6809:of σ- 5634:from 4903:is a 4855:from 4521:graph 4132:is a 2158:with 918:arity 894:arity 274:model 194:model 136:rings 11862:Type 11665:list 11469:list 11446:list 11435:Term 11369:rank 11263:open 11157:list 10969:Maps 10874:sets 10733:Free 10703:list 10453:list 10380:list 10297:ISBN 10275:ISBN 10238:ISBN 10212:ISBN 10190:ISBN 10165:ISBN 10136:ISBN 10114:ISBN 10092:ISBN 10068:ISBN 10022:ISBN 9894:and 9808:and 9633:ISBN 9559:and 9523:type 8044:(or 7465:cf. 7461:(or 7047:for 6928:and 6431:and 6237:and 5907:if: 4827:and 4669:and 4586:and 4416:Let 4406:join 4402:meet 4225:and 4023:hull 3186:and 3012:< 2880:and 2851:and 2475:is: 2221:and 1832:the 1762:and 1718:and 1630:and 1604:for 1086:-ary 978:The 831:The 711:and 142:and 119:and 107:, a 11549:of 11531:of 11479:of 11011:Sur 10985:Map 10792:Ur- 10774:Set 10267:doi 9989:doi 9945:in 9578:'s 9574:In 9517:In 9023:If 8820:By 8260:of 7874:of 7373:An 6884:of 6874:Hom 6856:of 6838:Hom 6834:Hom 6826:Emb 6822:Emb 6811:Hom 6803:Emb 6373:Hom 5854:Hom 5658:to 4905:map 4879:to 4177:If 4140:of 4074:or 4025:of 3998:by 3374:and 3159:if 3135:of 3025:or 2967:any 2934:of 2777:and 2706:and 2680:to 1001:of 896:of 705:of 544:or 516:dom 256:. 217:In 185:or 113:set 99:In 12094:: 11935:NP 11559:: 11553:: 11483:: 11160:), 11015:Bi 11007:In 10295:, 10273:, 10265:, 10261:: 10236:, 10210:, 10188:, 10163:, 10134:, 10130:, 10090:, 9995:, 9985:24 9983:, 9768:^ 9393:. 9015:). 8996:). 8983:). 8966:). 8941:). 8922:). 8905:). 7216:. 7008:. 6900:: 6840:. 6813:. 6774:, 6717:, 5860:. 5852:σ- 5842:. 5818:, 5760:, 5603:, 5530:, 4784:. 4516:. 4174:. 2428:0. 2398:ar 2357:ar 2316:ar 2275:ar 2234:ar 2137:ar 963:. 848:ar 801:ar 784:a 728:ar 666:ar 505:. 376:a 229:. 214:. 189:. 174:. 158:. 138:, 134:, 12015:/ 11930:P 11685:) 11471:) 11467:( 11364:∀ 11359:! 11354:∃ 11315:= 11310:↔ 11305:→ 11300:∧ 11295:∨ 11290:¬ 11013:/ 11009:/ 10983:/ 10794:) 10790:( 10677:∞ 10667:3 10455:) 10353:e 10346:t 10339:v 10326:) 10269:: 10003:. 9991:: 9958:. 9954:Q 9927:0 9923:N 9882:, 9879:2 9876:, 9873:1 9870:, 9867:0 9848:. 9843:f 9839:S 9796:, 9792:1 9788:, 9784:0 9751:. 9746:A 9719:| 9713:A 9707:| 9689:. 9641:. 9495:x 9491:y 9487:y 9483:x 9479:y 9456:x 9379:V 9374:| 9367:V 9361:| 9352:V 9347:| 9340:V 9334:| 9325:S 9320:| 9313:V 9307:| 9303:: 9297:V 9269:S 9264:| 9257:V 9251:| 9244:0 9241:= 9235:V 9229:S 9225:0 9202:V 9197:| 9190:V 9184:| 9177:0 9174:= 9168:V 9162:V 9158:0 9137:F 9134:= 9129:S 9124:| 9117:V 9111:| 9090:V 9087:= 9082:V 9077:| 9070:V 9064:| 9041:V 9029:F 9025:V 9013:V 9009:V 9005:S 8994:V 8989:V 8986:0 8981:V 8977:V 8972:V 8969:− 8964:V 8960:V 8956:V 8951:V 8948:+ 8939:S 8934:S 8928:S 8925:0 8920:S 8916:S 8911:S 8908:− 8903:S 8899:S 8895:S 8890:S 8884:S 8881:+ 8871:S 8867:V 8848:s 8839:s 8806:. 8801:M 8775:R 8755:, 8744:M 8720:M 8698:R 8678:, 8675:R 8653:M 8611:. 8606:M 8584:R 8564:R 8522:M 8500:R 8458:. 8455:} 8452:) 8447:n 8443:a 8439:, 8433:, 8428:1 8424:a 8420:( 8409:M 8404:: 8399:n 8395:M 8388:) 8383:n 8379:a 8375:, 8369:, 8364:1 8360:a 8356:( 8353:{ 8350:= 8347:R 8327:) 8322:n 8318:x 8314:, 8308:, 8303:1 8299:x 8295:( 8270:M 8248:M 8228:R 8208:n 8157:. 8134:R 8112:M 8078:- 8065:| 8059:M 8053:| 8028:R 8001:. 7998:) 7995:) 7992:x 7989:( 7980:m 7977:= 7974:x 7971:( 7968:x 7957:M 7935:) 7932:x 7929:( 7904:M 7882:M 7862:m 7839:) 7834:n 7830:a 7826:, 7820:, 7815:1 7811:a 7807:( 7796:M 7788:R 7782:) 7777:n 7773:a 7769:, 7763:, 7758:1 7754:a 7750:( 7710:R 7690:. 7687:} 7684:) 7679:n 7675:a 7671:, 7665:, 7660:1 7656:a 7652:( 7641:M 7636:: 7631:n 7627:M 7620:) 7615:n 7611:a 7607:, 7601:, 7596:1 7592:a 7588:( 7585:{ 7582:= 7579:R 7559:) 7554:n 7550:x 7546:, 7540:, 7535:1 7531:x 7527:( 7489:- 7443:M 7421:M 7401:R 7381:n 7349:. 7344:M 7322:T 7302:T 7280:M 7258:T 7229:M 7200:, 7197:M 7175:M 7124:M 7099:) 7096:I 7093:, 7087:, 7084:M 7081:( 7078:= 7073:M 6978:B 6968:A 6963:: 6960:h 6938:B 6914:A 6886:G 6878:H 6866:G 6862:H 6858:G 6854:H 6784:B 6760:A 6748:R 6731:B 6726:R 6702:A 6697:R 6668:B 6663:R 6656:) 6653:) 6648:n 6644:a 6640:( 6637:h 6634:, 6628:, 6625:) 6620:2 6616:a 6612:( 6609:h 6606:, 6603:) 6598:1 6594:a 6590:( 6587:h 6584:( 6573:A 6568:R 6561:) 6556:n 6552:a 6548:, 6542:, 6537:2 6533:a 6529:, 6524:1 6520:a 6516:( 6488:n 6484:a 6480:, 6474:, 6469:2 6465:a 6461:, 6456:1 6452:a 6441:R 6437:n 6409:B 6399:A 6394:: 6391:h 6356:. 6353:) 6348:n 6344:a 6340:( 6337:h 6334:= 6329:n 6325:b 6320:, 6313:, 6310:) 6305:2 6301:a 6297:( 6294:h 6291:= 6286:2 6282:b 6277:, 6274:) 6269:1 6265:a 6261:( 6258:h 6255:= 6250:1 6246:b 6222:A 6217:R 6210:) 6205:n 6201:a 6197:, 6191:, 6186:2 6182:a 6178:, 6173:1 6169:a 6165:( 6144:| 6138:A 6132:| 6123:n 6119:a 6115:, 6109:, 6104:2 6100:a 6096:, 6091:1 6087:a 6063:B 6058:R 6051:) 6046:n 6042:b 6038:, 6032:, 6027:2 6023:b 6019:, 6014:1 6010:b 6006:( 5985:| 5979:B 5973:| 5964:n 5960:b 5956:, 5950:, 5945:2 5941:b 5937:, 5932:1 5928:b 5917:R 5913:n 5889:B 5879:A 5874:: 5871:h 5828:B 5804:A 5781:| 5775:B 5769:| 5747:| 5741:A 5735:| 5724:h 5708:B 5698:A 5693:: 5690:h 5668:B 5644:A 5632:h 5613:B 5589:A 5567:R 5544:B 5539:R 5515:A 5510:R 5481:B 5476:R 5469:) 5466:) 5461:n 5457:a 5453:( 5450:h 5447:, 5441:, 5438:) 5433:2 5429:a 5425:( 5422:h 5419:, 5416:) 5411:1 5407:a 5403:( 5400:h 5397:( 5386:A 5381:R 5374:) 5369:n 5365:a 5361:, 5355:, 5350:2 5346:a 5342:, 5337:1 5333:a 5329:( 5302:| 5296:A 5290:| 5281:n 5277:a 5273:, 5267:, 5262:2 5258:a 5254:, 5249:1 5245:a 5234:R 5230:n 5221:. 5209:) 5206:) 5201:n 5197:a 5193:( 5190:h 5187:, 5181:, 5178:) 5173:2 5169:a 5165:( 5162:h 5159:, 5156:) 5151:1 5147:a 5143:( 5140:h 5137:( 5134:f 5131:= 5128:) 5125:) 5120:n 5116:a 5112:, 5106:, 5101:2 5097:a 5093:, 5088:1 5084:a 5080:( 5077:f 5074:( 5071:h 5044:| 5038:A 5032:| 5023:n 5019:a 5015:, 5009:, 5004:2 5000:a 4996:, 4991:1 4987:a 4976:f 4972:n 4953:| 4947:B 4941:| 4933:| 4927:A 4921:| 4917:: 4914:h 4889:B 4865:A 4837:B 4813:A 4764:, 4761:G 4741:H 4721:H 4701:G 4677:b 4657:a 4636:E 4628:) 4625:b 4622:, 4619:a 4616:( 4597:, 4594:b 4574:a 4554:. 4551:E 4460:} 4457:1 4454:, 4451:0 4448:, 4442:, 4436:, 4433:+ 4430:{ 4427:= 4381:. 4376:A 4354:B 4330:I 4309:, 4304:A 4282:) 4275:I 4271:, 4265:, 4262:B 4259:( 4239:A 4233:B 4213:) 4210:I 4207:, 4201:, 4198:A 4195:( 4192:= 4187:A 4161:| 4155:A 4149:| 4094:A 4085:B 4059:B 4036:, 4033:B 4009:, 4006:B 3982:. 3979:B 3958:| 3952:A 3946:| 3924:| 3918:A 3912:| 3905:B 3883:. 3880:B 3874:) 3869:n 3865:b 3861:, 3855:, 3850:2 3846:b 3842:, 3837:1 3833:b 3829:( 3826:f 3807:: 3804:B 3782:n 3778:b 3769:2 3765:b 3759:1 3755:b 3734:n 3714:f 3694:, 3691:B 3683:n 3679:b 3675:, 3669:, 3664:2 3660:b 3656:, 3651:1 3647:b 3624:A 3602:f 3582:n 3562:, 3559:n 3539:, 3534:A 3506:A 3483:| 3477:A 3471:| 3464:B 3442:. 3437:B 3427:A 3402:. 3398:| 3392:A 3386:| 3362:; 3358:| 3352:B 3346:| 3338:| 3332:A 3326:| 3306:: 3301:B 3277:A 3253:; 3250:) 3245:B 3240:( 3234:= 3231:) 3226:A 3221:( 3196:B 3172:A 3145:B 3117:A 3068:. 3037:, 2982:f 2951:f 2921:Z 2894:C 2889:I 2865:R 2860:I 2836:; 2833:1 2812:Q 2805:) 2802:1 2799:( 2793:Q 2788:I 2765:, 2762:0 2741:Q 2734:) 2731:0 2728:( 2722:Q 2717:I 2694:, 2691:x 2668:x 2647:Q 2639:Q 2635:: 2632:) 2626:( 2620:Q 2615:I 2591:Q 2583:Q 2575:Q 2571:: 2568:) 2562:( 2556:Q 2551:I 2527:Q 2519:Q 2511:Q 2507:: 2504:) 2501:+ 2498:( 2492:Q 2487:I 2460:Q 2455:I 2425:= 2417:) 2414:1 2411:( 2402:f 2390:, 2387:0 2384:= 2376:) 2373:0 2370:( 2361:f 2349:, 2346:1 2343:= 2335:) 2329:( 2320:f 2308:, 2305:2 2302:= 2294:) 2288:( 2279:f 2267:, 2264:2 2261:= 2253:) 2250:+ 2247:( 2238:f 2209:} 2206:1 2203:, 2200:0 2197:, 2191:, 2185:, 2182:+ 2179:{ 2176:= 2171:f 2167:S 2146:) 2141:f 2133:, 2128:f 2124:S 2120:( 2117:= 2112:f 2081:) 2075:C 2070:I 2066:, 2061:f 2053:, 2049:C 2045:( 2042:= 2033:C 2024:) 2018:R 2013:I 2009:, 2004:f 1996:, 1992:R 1988:( 1985:= 1976:R 1967:) 1961:Q 1956:I 1952:, 1947:f 1939:, 1935:Q 1931:( 1928:= 1919:Q 1873:, 1869:C 1844:R 1820:, 1816:Q 1792:A 1749:+ 1727:1 1705:0 1683:+ 1617:+ 1590:f 1558:. 1554:| 1548:A 1542:| 1533:2 1528:| 1521:A 1515:| 1511:: 1505:A 1500:f 1477:A 1467:2 1461:A 1455:: 1452:f 1432:, 1427:A 1405:f 1385:. 1382:) 1379:s 1376:( 1373:I 1353:s 1330:) 1327:c 1324:( 1321:I 1295:c 1275:0 1271:= 1248:) 1245:R 1242:( 1239:r 1236:a 1231:A 1224:) 1221:R 1218:( 1215:I 1212:= 1206:A 1201:R 1180:n 1160:n 1140:R 1120:) 1117:f 1114:( 1111:I 1108:= 1102:A 1097:f 1074:n 1053:n 1033:f 1011:A 989:I 931:. 928:s 904:s 880:s 860:) 857:s 854:( 845:= 842:n 816:. 813:) 810:s 807:( 798:= 795:n 772:s 750:0 745:N 737:S 731:: 693:S 669:) 663:, 660:S 657:( 654:= 615:A 593:, 588:A 565:| 559:A 553:| 532:) 527:A 522:( 413:I 390:, 364:, 361:A 336:) 333:I 330:, 324:, 321:A 318:( 315:= 310:A 263:) 259:( 90:) 84:( 79:) 75:( 61:. 34:. 20:)

Index

Relational structure
Mathematical model
references
inline citations
improve
introducing
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universal algebra
model theory
set
finitary operations
relations
algebraic structures
groups
rings
fields
vector spaces
first-order theories
relation symbols
Model theory
first-order theories
foundational
set theory
first-order logic
Tarski's theory of truth
Tarskian semantics
semantic model
mathematical models
interpretations
interpretation (model theory)

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