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Degeneracy (graph theory)

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27: 1185:− 1 – thus, the degeneracy is less than twice the arboricity. One may also compute in polynomial time an orientation of a graph that minimizes the outdegree but is not required to be acyclic. The edges of a graph with such an orientation may be partitioned in the same way into 258:, the minimum number of colors needed to color the vertices so that no two adjacent vertices have the same color; the ordering which determines the coloring number provides an order to color the vertices of G with the coloring number, but in general the chromatic number may be smaller. 285:
or fewer neighbors. The definition would be the same if arbitrary subgraphs are allowed in place of induced subgraphs, as a non-induced subgraph can only have vertex degrees that are smaller than or equal to the vertex degrees in the subgraph induced by the same vertex set.
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A 2-degenerate graph: each vertex has at most two neighbors to its left, so the rightmost vertex of any subgraph has degree at most two. Its 2-core, the subgraph remaining after repeatedly deleting vertices of degree less than two, is
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The two concepts of coloring number and degeneracy are equivalent: in any finite graph the degeneracy is just one less than the coloring number. For, if a graph has an ordering with coloring number κ then in each subgraph
1219: + 1; this is proved by a simple induction on the number of vertices which is exactly like the proof of the six-color theorem for planar graphs. Since chromatic number is an upper bound on the order of the 1300:
earlier neighbors. Therefore, the degeneracy is at most equal to the treewidth and at most equal to the pathwidth. However, there exist graphs with bounded degeneracy and unbounded treewidth, such as the
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has either an isolated vertex (incident to no edges) or a leaf vertex (incident to exactly one edge); therefore, trees and forests are 1-degenerate graphs. Every 1-degenerate graph is a forest.
748: 361:. Such an orientation can be formed by orienting each edge towards the earlier of its two endpoints in a coloring number ordering. In the other direction, if an orientation with outdegree 2600:
Garcia-Algarra, Javier; Pastor, Juan Manuel; Iriondo, Jose Maria; Galeano, Javier (2017), "Ranking of critical species to preserve the functionality of mutualistic networks using the
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in which each vertex has fewer than α neighbors that are earlier in the ordering. The inequality between coloring and chromatic numbers holds also in this infinite setting;
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Eppstein, D., Löffler, M., & Strash, D. (2010). Listing All Maximal Cliques in Sparse Graphs in Near-Optimal Time. In O. Cheong, K.-Y. Chwa, & K. Park (Eds.),
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has a vertex of degree five or less; therefore, every planar graph is 5-degenerate, and the degeneracy of any planar graph is at most five. Similarly, every
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Bader, Gary D.; Hogue, Christopher W. V. (2003), "An automated method for finding molecular complexes in large protein interaction networks",
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Although concepts of degeneracy and coloring number are frequently considered in the context of finite graphs, the original motivation for
569:. A survey of the topic, covering the main concepts, important algorithmic techniques as well as some application domains, may be found in 2731: 2104:
Asahiro, Yuichi; Miyano, Eiji; Ono, Hirotaka; Zenmyo, Kouhei (2006), "Graph orientation algorithms to minimize the maximum outdegree",
2068:-core decomposition: a tool for the visualization of large scale networks", in Weiss, Yair; Schölkopf, Bernhard; Platt, John (eds.), 1200:
orientation (by choosing an outdegree-1 orientation for each pseudoforest), so the minimum outdegree of such an orientation is the
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Altaf-Ul-Amin, M.; Nishikata, K.; Koma, T.; Miyasato, T.; Shinbo, Y.; Arifuzzaman, M.; Wada, C.; Maeda, M.; Oshima, T. (2003),
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in which each vertex has fewer than κ neighbors that are earlier in the ordering. It should be distinguished from the
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of the graph is regular of maximum degree. For all other graphs, the degeneracy is strictly less than the maximum degree.
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Kirkpatrick, Scott; Wilcke, Winfried W.; Garner, Robert B.; Huels, Harald (2002), "Percolation in dense storage arrays",
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previously-added vertices. It follows that any subgraph of a network formed in this way has a vertex of degree at most
136: 2683: 2113: 714: 3101: 3048: 2841: 2383: 211:(the last vertex in the subgraph to have been added to the graph) and Barabási–Albert networks are automatically 3039: 2876: 2095: 226:. More strongly, the degeneracy of a graph equals its maximum vertex degree if and only if at least one of the 2220: 2169: 2767:
Kowalik, Łukasz (2006), "Approximation scheme for lowest outdegree orientation and graph density measures",
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Malliaros, Fragkiskos D.; Giatsidis, Christos; Papadopoulos, Apostolos N.; Vazirgiannis, Michalis (2019),
1309: 189: 580: 2552:; Westermann, H. H. (1992), "Forests, frames, and games: algorithms for matroid sums and applications", 1348:-degenerate graphs grows linearly in the number of vertices of the graphs. The conjecture was proven by 2936:(1968), "A min-max theorem for graphs with application to graph coloring", SIAM 1968 National Meeting, 2487: 2320:
Infinite and finite sets (Colloq., Keszthely, 1973; dedicated to P. Erdős on his 60th birthday), Vol. 1
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vertex-disjoint paths. Since these paths must leave the two vertices of the pair via disjoint edges, a
1531:, one may define the coloring number analogously to the definition for finite graphs, as the smallest 3200: 3195: 3072: 2739: 1448: 1269:-cores but based on vertex connectivity have been studied in social network theory under the name of 1032: 2592: 1587: 1243: 1205: 2582:
Gaertler, Marco; Patrignani, Maurizio (2004), "Dynamic analysis of the autonomous system graph",
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is a graph that cannot be partitioned into more than one component by the removal of fewer than
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Alvarez-Hamelin, José Ignacio; Dall'Asta, Luca; Barrat, Alain; Vespignani, Alessandro (2006), "
1483: 350: 2678:, Wiley Series in Discrete Mathematics and Optimization, vol. 39, John Wiley & Sons, 1398: 2961:; Beck, L. L. (1983), "Smallest-last ordering and clustering and graph coloring algorithms", 2756: 2326:, Colloq. Math. Soc. János Bolyai, vol. 10, Amsterdam: North-Holland, pp. 214–240, 1706: 1555: 617: 588: 576: 354: 51: 2864: 1110: 3149: 2986: 2723: 2703: 2510: 2436: 2404: 2331: 2255: 2205: 2083: 2014: 513: 370: 2769:
Proceedings of the 17th International Symposium on Algorithms and Computation (ISAAC 2006)
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Graph Theory and Combinatorics, Proc. Cambridge Combinatorial Conf. in honor of Paul Erdős
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is also within a constant factor of the arboricity, and therefore also of the degeneracy.
8: 2108:, Darlinghurst, Australia, Australia: Australian Computer Society, Inc., pp. 11–20, 1270: 1154: 196: 167: 20: 2707: 2440: 2259: 2087: 2070:
Advances in Neural Information Processing Systems 18: Proceedings of the 2005 Conference
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Proc. 2nd International Workshop on Inter-Domain Performance and Simulation (IPS 2004)
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vertices, or equivalently a graph in which each pair of vertices can be connected by
178: 3178: 2926: 2575: 2197: 3158: 3134: 3110: 3081: 3057: 3020: 3002: 2994: 2972: 2947: 2914: 2885: 2850: 2828: 2816: 2776: 2748: 2711: 2655: 2623: 2613: 2563: 2542: 2528: 2496: 2444: 2392: 2360: 2263: 2213: 2193: 2143: 2133: 2022: 1201: 1027: 600: 274: 251: 47: 3007:"Structural cohesion and embeddedness: a hierarchical conception of social groups" 2667: 2475: 2448: 2283: 2053: 1547:
state that, at the time of publication of their paper, it was already well known.
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and is last in the ordering has at most κ − 1 neighbors in
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Freuder, Eugene C. (1982), "A sufficient condition for backtrack-free search",
2378: 2339: 1983: 1333: 1220: 558: 550: 3139: 2752: 2344:"Planar orientations with low out-degree and compaction of adjacency matrices" 2224: 2106:
CATS '06: Proceedings of the 12th Computing: The Australasian Theory Symposium
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it is, and is within a constant factor of other sparsity measures such as the
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to be the least κ for which there exists an ordering of the vertices of
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and repeatedly removing the vertex with the smallest degree. The degeneracy
26: 3170: 3162: 3096: 2958: 2933: 2855: 2646: 2637: 2554: 2479: 2456: 2318: 2275: 2172:(2012), "The sharp threshold for bootstrap percolation in all dimensions", 2157: 1567: 1189: 754: 554: 193: 174: 113: 36: 2897: 2533: 2138: 1982:(Vol. 6506, pp. 403–414). Berlin, Heidelberg: Springer Berlin Heidelberg. 1181: − 1) edges and therefore has a vertex of degree at most 2 570: 2938: 2900:"The core decomposition of networks: theory, algorithms and applications" 2431: 2310: 2250: 1228: 761:
is given by the highest degree of any vertex at the time of its removal.
132: 75: 2977: 2780: 2039:-cores of protein-protein interaction networks and amino acid sequences" 1856: 3032: 2659: 2618: 2567: 2501: 2000: 1302: 1223:, the latter invariant is also at most degeneracy plus one. By using a 1158: 79: 1157:
by choosing one forest for each outgoing edge of each node. Thus, the
2317:(1975), "On the magnitude of generalized Ramsey numbers for graphs", 1908: 1281: 1277: 135:
by an algorithm that repeatedly removes minimum-degree vertices. The
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Wuchty, S.; Almaas, E. (2005), "Peeling the yeast protein network",
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Seidman, Stephen B. (1983), "Network structure and minimum degree",
3024: 2951: 2811: 2078: 1725:)-regular component." In the notation used by Jensen and Toft, col( 750: 2599: 2188: 2032: 1838: 1806: 614:
outline an algorithm to derive the degeneracy ordering of a graph
591:. It consists of selecting a random subset of active cells from a 2163: 1850: 1512:, so the class of graphs with bounded degeneracy is said to have 566: 798:. Initially, these numbers are just the degrees of the vertices. 150:
of the graph and the degeneracy of a graph is the largest value
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algorithm on an ordering with optimal coloring number, one can
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is at most equal to its degeneracy. In the other direction, an
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formed by repeatedly deleting all vertices of degree less than
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Lee, Choongbum (2017), "Ramsey numbers of degenerate graphs",
2411:
Dorogovtsev, S. N.; Goltsev, A. V.; Mendes, J. F. F. (2006), "
1340:. Specifically, the conjecture is that for any fixed value of 314: + 1 can be obtained by repeatedly finding a vertex 3099:(1968), "An inequality for the chromatic number of a graph", 2691: 1862: 326:
from the graph, ordering the remaining vertices, and adding
1624: 704:{\displaystyle {\mathcal {O}}(\vert V\vert +\vert E\vert )} 74:-degenerate. The degeneracy of a graph is a measure of how 2644:
Irani, Sandy (1994), "Coloring inductive graphs on-line",
549:-core was introduced to study the clustering structure of 3123:
Venkateswaran, V. (2004), "Minimizing maximum indegree",
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was the theory of infinite graphs. For an infinite graph
2410: 1790: 1192:, and conversely any partition of a graph's edges into 2381:(1991), "On the thickness and arboricity of a graph", 2103: 1898: 1636: 1401: 1261:-vertex-connected graph must have degeneracy at least 1204:, which again is at most equal to the degeneracy. The 2695:
Physica A: Statistical Mechanics and its Applications
2006:
Physica A: Statistical Mechanics and its Applications
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such that each vertex that is added to the graph has
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that are left after all vertices of degree less than
925:to the cell of D corresponding to the new value of 764:In more detail, the algorithm proceeds as follows: 310:-degenerate, then an ordering with coloring number 2581: 1822: 1612: 1504: 1472: 1437: 1387: 1367: 1122: 1095: 1054: 1010: 959: 753:of space, by storing vertices in a degree-indexed 742: 703: 644: 534: 502: 482: 459: 2175:Transactions of the American Mathematical Society 1868: 3187: 3046:(1984), "Graph minors. III. Planar tree-width", 3038: 2729: 1954: 1648: 1630: 2548: 2480:"On chromatic number of graphs and set-systems" 2337: 1890: 1886: 1758: 1215:-degenerate graph has chromatic number at most 233: 131:. The degeneracy of a graph may be computed in 58:: that is, some vertex in the subgraph touches 2219: 1690: 143:have been (repeatedly) removed are called the 3122: 1894: 1550:The degeneracy of random subsets of infinite 743:{\displaystyle {\mathcal {O}}(\vert V\vert )} 3146: 3091: 1984:https://doi.org/10.1007/978-3-642-17517-6_36 1930: 1810: 734: 728: 695: 689: 683: 677: 345: + 1) if and only if the edges of 341:-degenerate (or has coloring number at most 117: 2470: 2072:, vol. 18, The MIT Press, p. 41, 1926: 1642: 1544: 1524: 1169:-vertex graph that can be partitioned into 400:in which all vertices have degree at least 365:is given, an ordering with coloring number 243: 222:-regular graph has degeneracy exactly  3000: 2957: 2673: 2301:(1984), "The evolution of sparse graphs", 2121: 2035:"Prediction of protein functions based on 1942: 1802: 1702: 1666: 1606: 611: 3138: 3114: 3061: 2976: 2889: 2854: 2834: 2810: 2730:Kirousis, L. M.; Thilikos, D. M. (1996), 2627: 2617: 2591: 2532: 2500: 2430: 2415:-core organization of complex networks", 2364: 2309: 2249: 2229:"Emergence of scaling in random networks" 2187: 2147: 2137: 2077: 1966: 1915:Dean, Hutchinson & Scheinerman (1991) 1746: 1729:) is the degeneracy plus one, and Δ( 1678: 1466: 1465: 1150:, then its edges may be partitioned into 595:or other space, and then considering the 373:of the resulting directed acyclic graph. 266: 124:-degenerate graphs have also been called 2835:Lick, Don R.; White, Arthur T. (1970), " 2297: 1791:Dorogovtsev, Goltsev & Mendes (2006) 1782: 938:At the end of the algorithm, any vertex 333:A third, equivalent formulation is that 50:in which every subgraph has a vertex of 25: 3069: 2766: 2674:Jensen, Tommy R.; Toft, Bjarne (2011), 2516: 1902: 1770: 1618: 1146:is oriented acyclically with outdegree 3188: 2932: 2862: 1786: 1742: 1328:such that any two-edge-coloring of an 62:or fewer of the subgraph's edges. The 2771:, Lecture Notes in Computer Science, 2643: 1999: 1874: 1654: 1336:must contain a monochromatic copy of 100:, and is essentially the same as the 1196:pseudoforests leads to an outdegree- 369: + 1 can be obtained as a 181:has degeneracy at most two, and the 66:of a graph is the smallest value of 2796: 1554:has been studied under the name of 1349: 13: 1518: 1312:relates the degeneracy of a graph 1138:Relation to other graph parameters 720: 669: 579:is a random process studied as an 23:of a graph is a different concept. 14: 3212: 2003:(1991), "Bootstrap percolation", 1296:in which each vertex has at most 1062:that are induced by the vertices 553:and to describe the evolution of 404:. Equivalently, it is one of the 85:Degeneracy is also known as the 2305:, Academic Press, pp. 35–57 1823:Gaertler & Patrignani (2004) 1535:α such that there exists a 1235:-degenerate graph using at most 1107:is the first vertex with degree 809:contains a list of the vertices 565:, and resilience of networks in 3102:Journal of Combinatorial Theory 3049:Journal of Combinatorial Theory 2842:Canadian Journal of Mathematics 2384:Journal of Combinatorial Theory 2198:10.1090/S0002-9947-2011-05552-2 1972: 1960: 1948: 1936: 1920: 1880: 1816: 1796: 1776: 1764: 1752: 1736: 1733:) is the maximum vertex degree. 1717:) + 1 if and only if 1473:{\displaystyle d\equiv 0\mod 3} 1461: 238:The coloring number of a graph 2865:"Size and connectivity of the 1955:Robertson & Seymour (1984) 1709:: "It is easy to see that col( 1696: 1684: 1672: 1631:Kirousis & Thilikos (1996) 1414: 1402: 1375:-vertex graph with degeneracy 1090: 1072: 1055:{\displaystyle H_{l}\subset G} 1005: 981: 954: 948: 737: 725: 698: 674: 639: 627: 557:. It has also been applied in 529: 517: 1: 3116:10.1016/S0021-9800(68)80081-X 2716:10.1016/S0378-4371(02)01153-6 2449:10.1103/PhysRevLett.96.040601 1992: 1891:Gabow & Westermann (1992) 1887:Chrobak & Eppstein (1991) 1827:Alvarez-Hamelin et al. (2006) 1759:Chrobak & Eppstein (1991) 1288:, then it is a subgraph of a 790:, the number of neighbors of 606: 420:-core exists, then, clearly, 302:. In the other direction, if 199:is parameterized by a number 19:"K-core" redirects here. The 16:Measurement of graph sparsity 3126:Discrete Applied Mathematics 3086:10.1016/0378-8733(83)90028-X 3063:10.1016/0095-8956(84)90013-3 3012:American Sociological Review 2891:10.1016/0012-365X(91)90162-U 2775:, Springer-Verlag: 557–566, 2397:10.1016/0095-8956(91)90100-X 2366:10.1016/0304-3975(91)90020-3 2352:Theoretical Computer Science 2268:10.1126/science.286.5439.509 2027:10.1016/0378-4371(91)90295-n 1839:Garcia-Algarra et al. (2017) 1691:Barabási & Albert (1999) 1294:perfect elimination ordering 234:Definitions and equivalences 7: 2821:10.4007/annals.2017.185.3.2 1807:Altaf-Ul-Amin et al. (2003) 1749:, Proposition 1, page 1084. 1561: 1130:at the time it is added to 294:the vertex that belongs to 161: 10: 3217: 2919:10.1007/s00778-019-00587-4 2488:Acta Mathematica Hungarica 1980:Algorithms and Computation 1931:Szekeres & Wilf (1968) 1811:Wuchty & Almaas (2005) 768:Initialize an output list 376: 349:can be oriented to form a 261:The degeneracy of a graph 18: 3140:10.1016/j.dam.2003.07.007 2753:10.1137/S0097539793255709 2740:SIAM Journal on Computing 2052:: 498–499, archived from 1927:Erdős & Hajnal (1966) 1863:Kirkpatrick et al. (2002) 1643:Erdős & Hajnal (1966) 1545:Erdős & Hajnal (1966) 1525:Erdős & Hajnal (1966) 1505:{\displaystyle n\geq d+3} 1445:maximal cliques whenever 1438:{\textstyle (n-d)3^{d/3}} 330:to the end of the order. 244:Erdős & Hajnal (1966) 2869:-core of a random graph" 2732:"The linkage of a graph" 1943:Moody & White (2003) 1803:Bader & Hogue (2003) 1703:Jensen & Toft (2011) 1667:Matula & Beck (1983) 1607:Bader & Hogue (2003) 1593: 1583:Core–periphery structure 813:that are not already in 794:that are not already in 612:Matula & Beck (1983) 428:, and the degeneracy of 424:has degeneracy at least 2863:Łuczak, Tomasz (1991), 2676:Graph Coloring Problems 2418:Physical Review Letters 2221:Barabási, Albert-László 2168:; Duminil-Copin, Hugo; 1967:Burr & Erdős (1975) 1747:Lick & White (1970) 1679:Lick & White (1970) 1344:, the Ramsey number of 1247:-vertex-connected graph 1239: + 1 colors. 853:, ... until finding an 645:{\displaystyle G=(V,E)} 571:Malliaros et al. (2019) 281:contains a vertex with 267:Lick & White (1970) 185:have degeneracy three. 3163:10.1002/pmic.200400962 2856:10.4153/CJM-1970-125-1 2604:-core decomposition", 2379:Scheinerman, Edward R. 1506: 1474: 1439: 1389: 1369: 1265:. Concepts related to 1124: 1123:{\displaystyle \geq l} 1097: 1056: 1012: 971:edges to the vertices 961: 744: 705: 646: 536: 504: 484: 461: 396:connected subgraph of 351:directed acyclic graph 32: 2839:-degenerate graphs", 2799:Annals of Mathematics 2534:10.1145/322290.322292 2139:10.1186/1471-2105-4-2 1899:Asahiro et al. (2006) 1713:) = Δ( 1588:Cereceda's conjecture 1556:bootstrap percolation 1507: 1475: 1440: 1390: 1370: 1310:Burr–Erdős conjecture 1125: 1098: 1057: 1013: 962: 845:Scan the array cells 745: 706: 647: 589:distributed computing 577:Bootstrap percolation 563:network visualization 537: 535:{\displaystyle (c+1)} 510:-core but not to any 505: 485: 462: 190:Barabási–Albert model 29: 2877:Discrete Mathematics 1895:Venkateswaran (2004) 1851:Balogh et al. (2012) 1484: 1449: 1399: 1379: 1359: 1173:forests has at most 1111: 1066: 1033: 975: 942: 914:, subtract one from 891:to the beginning of 801:Initialize an array 715: 664: 618: 514: 494: 474: 451: 406:connected components 371:topological ordering 322:neighbors, removing 228:connected components 137:connected components 106:Szekeres–Wilf number 2978:10.1145/2402.322385 2781:10.1007/11940128_56 2708:2002PhyA..314..220K 2441:2006PhRvL..96d0601D 2375:Hutchinson, Joan P. 2260:1999Sci...286..509B 2088:2005cs........4107A 2019:1991PhyA..171..453A 1539:of the vertices of 1271:structural cohesion 895:and remove it from 583:and as a model for 490:if it belongs to a 408:of the subgraph of 197:scale-free networks 183:Apollonian networks 154:such that it has a 2964:Journal of the ACM 2660:10.1007/BF01294263 2619:10.7717/peerj.3321 2586:, pp. 13–24, 2568:10.1007/BF01758774 2520:Journal of the ACM 2502:10.1007/BF02020444 2125:BMC Bioinformatics 2046:Genome Informatics 1578:Percolation Theory 1502: 1470: 1435: 1385: 1365: 1120: 1093: 1052: 1008: 967:will have at most 957: 902:For each neighbor 740: 701: 642: 532: 500: 480: 457: 33: 3003:White, Douglas R. 2790:978-3-540-49694-6 2244:(5439): 509–512, 1388:{\displaystyle d} 1368:{\displaystyle n} 1096:{\displaystyle L} 1011:{\displaystyle L} 960:{\displaystyle L} 775:Compute a number 545:The concept of a 503:{\displaystyle c} 483:{\displaystyle c} 460:{\displaystyle u} 416:. If a non-empty 388:-core of a graph 179:outerplanar graph 129:-inductive graphs 44:-degenerate graph 3208: 3201:Graph algorithms 3196:Graph invariants 3181: 3143: 3142: 3133:(1–3): 374–378, 3119: 3118: 3097:Wilf, Herbert S. 3093:Szekeres, George 3088: 3066: 3065: 3035: 2997: 2980: 2959:Matula, David W. 2954: 2934:Matula, David W. 2929: 2907:The VLDB Journal 2904: 2894: 2893: 2873: 2868: 2859: 2858: 2849:(5): 1082–1096, 2838: 2831: 2814: 2793: 2763: 2761: 2755:, archived from 2736: 2726: 2702:(1–4): 220–229, 2688: 2670: 2640: 2631: 2621: 2603: 2596: 2595: 2578: 2545: 2536: 2513: 2504: 2484: 2467: 2434: 2432:cond-mat/0509102 2414: 2407: 2373:Dean, Alice M.; 2369: 2368: 2348: 2338:Chrobak, Marek; 2334: 2325: 2306: 2294: 2292: 2286:, archived from 2253: 2251:cond-mat/9910332 2233: 2216: 2191: 2182:(5): 2667–2701, 2164:Balogh, József; 2160: 2151: 2141: 2118: 2100: 2081: 2067: 2060: 2058: 2043: 2038: 2029: 1986: 1976: 1970: 1964: 1958: 1952: 1946: 1940: 1934: 1924: 1918: 1912: 1906: 1884: 1878: 1872: 1866: 1860: 1854: 1848: 1842: 1836: 1830: 1820: 1814: 1800: 1794: 1780: 1774: 1768: 1762: 1756: 1750: 1740: 1734: 1700: 1694: 1688: 1682: 1676: 1670: 1664: 1658: 1652: 1646: 1640: 1634: 1628: 1622: 1616: 1610: 1604: 1511: 1509: 1508: 1503: 1479: 1477: 1476: 1471: 1444: 1442: 1441: 1436: 1434: 1433: 1429: 1394: 1392: 1391: 1386: 1374: 1372: 1371: 1366: 1202:pseudoarboricity 1133: 1129: 1127: 1126: 1121: 1106: 1102: 1100: 1099: 1094: 1061: 1059: 1058: 1053: 1045: 1044: 1025: 1021: 1017: 1015: 1014: 1009: 970: 966: 964: 963: 958: 879:Select a vertex 782:for each vertex 760: 749: 747: 746: 741: 724: 723: 710: 708: 707: 702: 673: 672: 659: 655: 652:with vertex set 651: 649: 648: 643: 603:of this subset. 601:induced subgraph 598: 541: 539: 538: 533: 509: 507: 506: 501: 489: 487: 486: 481: 466: 464: 463: 458: 275:induced subgraph 273:such that every 252:chromatic number 70:for which it is 48:undirected graph 3216: 3215: 3211: 3210: 3209: 3207: 3206: 3205: 3186: 3185: 3184: 3073:Social Networks 3040:Robertson, Neil 3025:10.2307/3088904 2952:10.1137/1010115 2902: 2871: 2866: 2836: 2791: 2759: 2734: 2686: 2601: 2482: 2412: 2346: 2340:Eppstein, David 2323: 2311:Burr, Stefan A. 2290: 2231: 2116: 2098: 2065: 2056: 2041: 2036: 1995: 1990: 1989: 1977: 1973: 1965: 1961: 1953: 1949: 1941: 1937: 1925: 1921: 1913: 1909: 1885: 1881: 1873: 1869: 1861: 1857: 1849: 1845: 1837: 1833: 1821: 1817: 1801: 1797: 1783:Bollobás (1984) 1781: 1777: 1769: 1765: 1757: 1753: 1741: 1737: 1701: 1697: 1689: 1685: 1677: 1673: 1665: 1661: 1653: 1649: 1641: 1637: 1629: 1625: 1617: 1613: 1605: 1601: 1596: 1573:Network science 1564: 1533:cardinal number 1521: 1519:Infinite graphs 1485: 1482: 1481: 1450: 1447: 1446: 1425: 1421: 1417: 1400: 1397: 1396: 1380: 1377: 1376: 1360: 1357: 1356: 1276:If a graph has 1225:greedy coloring 1140: 1131: 1112: 1109: 1108: 1104: 1067: 1064: 1063: 1040: 1036: 1034: 1031: 1030: 1023: 1019: 976: 973: 972: 968: 943: 940: 939: 930: 919: 910:not already in 822: 780: 758: 719: 718: 716: 713: 712: 668: 667: 665: 662: 661: 657: 653: 619: 616: 615: 609: 596: 585:fault tolerance 551:social networks 515: 512: 511: 495: 492: 491: 475: 472: 471: 452: 449: 448: 432:is the largest 382: 265:was defined by 242:was defined by 236: 192:for generating 164: 102:coloring number 24: 17: 12: 11: 5: 3214: 3204: 3203: 3198: 3183: 3182: 3157:(2): 444–449, 3144: 3120: 3089: 3080:(3): 269–287, 3067: 3036: 3001:Moody, James; 2998: 2971:(3): 417–427, 2955: 2946:(4): 481–482, 2930: 2895: 2860: 2832: 2805:(3): 791–829, 2794: 2789: 2764: 2747:(3): 626–647, 2727: 2689: 2684: 2671: 2641: 2597: 2593:10.1.1.81.6841 2579: 2562:(1): 465–497, 2546: 2514: 2495:(1–2): 61–99, 2476:Hajnal, András 2468: 2408: 2391:(1): 147–151, 2370: 2359:(2): 243–266, 2335: 2307: 2299:Bollobás, Béla 2295: 2217: 2170:Morris, Robert 2166:Bollobás, Béla 2161: 2119: 2114: 2101: 2096: 2061: 2030: 2013:(3): 453–470, 1996: 1994: 1991: 1988: 1987: 1971: 1959: 1947: 1935: 1919: 1907: 1903:Kowalik (2006) 1879: 1867: 1855: 1843: 1831: 1815: 1795: 1775: 1771:Seidman (1983) 1763: 1751: 1735: 1695: 1683: 1671: 1659: 1647: 1635: 1623: 1619:Freuder (1982) 1611: 1598: 1597: 1595: 1592: 1591: 1590: 1585: 1580: 1575: 1570: 1563: 1560: 1520: 1517: 1501: 1498: 1495: 1492: 1489: 1469: 1464: 1460: 1457: 1454: 1432: 1428: 1424: 1420: 1416: 1413: 1410: 1407: 1404: 1384: 1364: 1334:complete graph 1221:maximum clique 1139: 1136: 1119: 1116: 1092: 1089: 1086: 1083: 1080: 1077: 1074: 1071: 1051: 1048: 1043: 1039: 1007: 1004: 1001: 998: 995: 992: 989: 986: 983: 980: 956: 953: 950: 947: 936: 935: 934: 933: 928: 917: 900: 877: 862: 836: 829: 820: 799: 778: 773: 739: 736: 733: 730: 727: 722: 700: 697: 694: 691: 688: 685: 682: 679: 676: 671: 641: 638: 635: 632: 629: 626: 623: 608: 605: 581:epidemic model 559:bioinformatics 531: 528: 525: 522: 519: 499: 479: 456: 381: 375: 235: 232: 163: 160: 15: 9: 6: 4: 3: 2: 3213: 3202: 3199: 3197: 3194: 3193: 3191: 3180: 3176: 3172: 3168: 3164: 3160: 3156: 3152: 3151: 3145: 3141: 3136: 3132: 3128: 3127: 3121: 3117: 3112: 3108: 3104: 3103: 3098: 3094: 3090: 3087: 3083: 3079: 3075: 3074: 3068: 3064: 3059: 3055: 3051: 3050: 3045: 3044:Seymour, Paul 3041: 3037: 3034: 3030: 3026: 3022: 3018: 3014: 3013: 3008: 3004: 2999: 2996: 2992: 2988: 2984: 2979: 2974: 2970: 2966: 2965: 2960: 2956: 2953: 2949: 2945: 2941: 2940: 2935: 2931: 2928: 2924: 2920: 2916: 2912: 2908: 2901: 2896: 2892: 2887: 2883: 2879: 2878: 2870: 2861: 2857: 2852: 2848: 2844: 2843: 2833: 2830: 2826: 2822: 2818: 2813: 2808: 2804: 2800: 2795: 2792: 2786: 2782: 2778: 2774: 2770: 2765: 2762:on 2011-07-21 2758: 2754: 2750: 2746: 2742: 2741: 2733: 2728: 2725: 2721: 2717: 2713: 2709: 2705: 2701: 2697: 2696: 2690: 2687: 2685:9781118030745 2681: 2677: 2672: 2669: 2665: 2661: 2657: 2653: 2649: 2648: 2642: 2639: 2635: 2630: 2625: 2620: 2615: 2611: 2607: 2598: 2594: 2589: 2585: 2580: 2577: 2573: 2569: 2565: 2561: 2557: 2556: 2551: 2547: 2544: 2540: 2535: 2530: 2526: 2522: 2521: 2515: 2512: 2508: 2503: 2498: 2494: 2490: 2489: 2481: 2477: 2473: 2469: 2466: 2462: 2458: 2454: 2450: 2446: 2442: 2438: 2433: 2428: 2425:(4): 040601, 2424: 2420: 2419: 2409: 2406: 2402: 2398: 2394: 2390: 2386: 2385: 2380: 2376: 2371: 2367: 2362: 2358: 2354: 2353: 2345: 2341: 2336: 2333: 2329: 2322: 2321: 2316: 2312: 2308: 2304: 2300: 2296: 2293:on 2006-11-11 2289: 2285: 2281: 2277: 2273: 2269: 2265: 2261: 2257: 2252: 2247: 2243: 2239: 2238: 2230: 2226: 2222: 2218: 2215: 2211: 2207: 2203: 2199: 2195: 2190: 2185: 2181: 2177: 2176: 2171: 2167: 2162: 2159: 2155: 2150: 2145: 2140: 2135: 2131: 2127: 2126: 2120: 2117: 2115:1-920682-33-3 2111: 2107: 2102: 2099: 2093: 2089: 2085: 2080: 2075: 2071: 2062: 2059:on 2007-09-27 2055: 2051: 2047: 2040: 2031: 2028: 2024: 2020: 2016: 2012: 2008: 2007: 2002: 1998: 1997: 1985: 1981: 1975: 1968: 1963: 1956: 1951: 1944: 1939: 1932: 1928: 1923: 1916: 1911: 1904: 1900: 1896: 1892: 1888: 1883: 1876: 1871: 1864: 1859: 1852: 1847: 1840: 1835: 1828: 1824: 1819: 1812: 1808: 1804: 1799: 1792: 1788: 1787:Łuczak (1991) 1784: 1779: 1772: 1767: 1760: 1755: 1748: 1744: 1743:Matula (1968) 1739: 1732: 1728: 1724: 1721:has a Δ( 1720: 1716: 1712: 1708: 1704: 1699: 1692: 1687: 1680: 1675: 1668: 1663: 1656: 1651: 1644: 1639: 1632: 1627: 1620: 1615: 1608: 1603: 1599: 1589: 1586: 1584: 1581: 1579: 1576: 1574: 1571: 1569: 1566: 1565: 1559: 1557: 1553: 1548: 1546: 1542: 1538: 1537:well-ordering 1534: 1530: 1526: 1516: 1515: 1499: 1496: 1493: 1490: 1487: 1467: 1462: 1458: 1455: 1452: 1430: 1426: 1422: 1418: 1411: 1408: 1405: 1382: 1362: 1353: 1351: 1347: 1343: 1339: 1335: 1331: 1327: 1323: 1319: 1318:Ramsey number 1315: 1311: 1306: 1304: 1299: 1295: 1291: 1290:chordal graph 1287: 1283: 1279: 1274: 1272: 1268: 1264: 1260: 1256: 1252: 1248: 1246: 1240: 1238: 1234: 1230: 1226: 1222: 1218: 1214: 1209: 1207: 1203: 1199: 1195: 1191: 1190:pseudoforests 1188: 1184: 1180: 1176: 1172: 1168: 1164: 1160: 1156: 1153: 1149: 1145: 1135: 1117: 1114: 1087: 1084: 1081: 1078: 1075: 1069: 1049: 1046: 1041: 1037: 1029: 1002: 999: 996: 993: 990: 987: 984: 978: 951: 945: 931: 924: 920: 913: 909: 905: 901: 898: 894: 890: 886: 882: 878: 875: 871: 867: 863: 860: 856: 852: 848: 844: 843: 841: 837: 834: 830: 827: 824: =  823: 816: 812: 808: 804: 800: 797: 793: 789: 785: 781: 774: 771: 767: 766: 765: 762: 756: 752: 731: 692: 686: 680: 656:and edge set 636: 633: 630: 624: 621: 613: 604: 602: 599:-core of the 594: 590: 586: 582: 578: 574: 572: 568: 564: 560: 556: 555:random graphs 552: 548: 543: 526: 523: 520: 497: 477: 470: 454: 445: 443: 439: 435: 431: 427: 423: 419: 415: 411: 407: 403: 399: 395: 391: 387: 379: 374: 372: 368: 364: 360: 356: 352: 348: 344: 340: 336: 331: 329: 325: 321: 318:with at most 317: 313: 309: 305: 301: 297: 293: 287: 284: 280: 276: 272: 269:as the least 268: 264: 259: 257: 253: 249: 245: 241: 231: 229: 225: 221: 216: 215:-degenerate. 214: 210: 206: 202: 198: 195: 191: 186: 184: 180: 176: 173:Every finite 171: 169: 166:Every finite 159: 157: 153: 149: 147: 142: 138: 134: 130: 128: 123: 119: 115: 112: and 111: 108:(named after 107: 103: 99: 95: 91: 89: 83: 81: 77: 73: 69: 65: 61: 57: 53: 49: 45: 43: 38: 28: 22: 3154: 3148: 3130: 3124: 3106: 3100: 3077: 3071: 3056:(1): 49–64, 3053: 3052:, Series B, 3047: 3016: 3010: 2968: 2962: 2943: 2937: 2910: 2906: 2884:(1): 61–68, 2881: 2875: 2846: 2840: 2802: 2798: 2772: 2768: 2757:the original 2744: 2738: 2699: 2693: 2675: 2654:(1): 53–72, 2651: 2647:Algorithmica 2645: 2609: 2605: 2583: 2559: 2555:Algorithmica 2553: 2550:Gabow, H. N. 2527:(1): 24–32, 2524: 2518: 2492: 2486: 2422: 2416: 2388: 2387:, Series B, 2382: 2356: 2350: 2319: 2302: 2288:the original 2241: 2235: 2225:Albert, Réka 2179: 2173: 2129: 2123: 2105: 2069: 2054:the original 2049: 2045: 2010: 2004: 1979: 1974: 1962: 1950: 1938: 1922: 1910: 1882: 1875:Adler (1991) 1870: 1858: 1846: 1834: 1818: 1798: 1778: 1766: 1754: 1738: 1730: 1726: 1722: 1718: 1714: 1710: 1698: 1686: 1674: 1662: 1655:Irani (1994) 1650: 1638: 1626: 1614: 1602: 1568:Graph theory 1549: 1540: 1528: 1522: 1514:few cliques. 1395:has at most 1354: 1345: 1341: 1337: 1329: 1325: 1324:, the least 1321: 1313: 1307: 1297: 1292:which has a 1285: 1275: 1266: 1262: 1258: 1254: 1250: 1244: 1241: 1236: 1232: 1216: 1212: 1210: 1197: 1193: 1186: 1182: 1178: 1174: 1170: 1166: 1162: 1151: 1147: 1143: 1141: 937: 926: 922: 915: 911: 907: 903: 896: 892: 888: 884: 880: 873: 869: 865: 861:is nonempty. 858: 854: 850: 846: 839: 832: 825: 818: 814: 810: 806: 802: 795: 791: 787: 783: 776: 769: 763: 755:bucket queue 610: 575: 546: 544: 468: 446: 441: 437: 433: 429: 425: 421: 417: 413: 409: 401: 397: 389: 385: 383: 377: 366: 362: 358: 346: 342: 338: 334: 332: 327: 323: 319: 315: 311: 307: 303: 299: 295: 291: 288: 282: 278: 270: 262: 260: 255: 247: 239: 237: 223: 219: 217: 212: 208: 204: 200: 187: 175:planar graph 172: 165: 155: 151: 145: 144: 140: 126: 125: 121: 105: 101: 97: 93: 90:-core number 87: 86: 84: 82:of a graph. 71: 67: 63: 59: 55: 41: 40: 37:graph theory 34: 3019:(1): 1–25, 2939:SIAM Review 2472:Erdős, Paul 2315:Erdős, Paul 2001:Adler, Joan 1303:grid graphs 1229:graph color 1142:If a graph 831:Initialize 133:linear time 3190:Categories 3150:Proteomics 2812:1505.04773 2097:0262232537 2079:cs/0504107 1993:References 1707:p. 78 1350:Lee (2017) 1159:arboricity 1022:-cores of 857:for which 817:for which 805:such that 607:Algorithms 436:for which 80:arboricity 64:degeneracy 2913:: 61–92, 2612:: e3321, 2588:CiteSeerX 2189:1010.3326 1491:≥ 1456:≡ 1409:− 1282:pathwidth 1278:treewidth 1206:thickness 1115:≥ 1082:… 1047:⊂ 1028:subgraphs 1000:− 991:… 921:and move 711:time and 447:A vertex 355:outdegree 3179:17659720 3171:15627958 3005:(2003), 2927:85519668 2638:28533969 2576:40358357 2478:(1966), 2457:16486798 2342:(1991), 2276:10521342 2227:(1999), 2158:12525261 2132:(1): 2, 1562:See also 1552:lattices 1332:-vertex 1284:at most 1103:, where 1026:are the 469:coreness 357:at most 162:Examples 110:Szekeres 54:at most 3109:: 1–3, 3033:3088904 2995:4417741 2987:0709826 2829:7974973 2724:1961703 2704:Bibcode 2629:5438587 2543:8624975 2511:0193025 2437:Bibcode 2405:1109429 2332:0371701 2256:Bibcode 2237:Science 2214:2708046 2206:2888224 2084:Bibcode 2015:Bibcode 1316:to the 1155:forests 868:to max( 842:times: 838:Repeat 593:lattice 567:ecology 542:-core. 444:-core. 394:maximal 158:-core. 116: ( 98:linkage 31:shaded. 3177:  3169:  3031:  2993:  2985:  2925:  2827:  2787:  2722:  2682:  2668:181800 2666:  2636:  2626:  2590:  2574:  2541:  2509:  2463:  2455:  2403:  2330:  2284:524106 2282:  2274:  2212:  2204:  2156:  2149:149346 2146:  2112:  2094:  1018:. The 887:. Add 440:has a 380:-Cores 218:Every 194:random 168:forest 148:-cores 96:, and 76:sparse 52:degree 46:is an 3175:S2CID 3029:JSTOR 2991:S2CID 2923:S2CID 2903:(PDF) 2872:(PDF) 2825:S2CID 2807:arXiv 2760:(PDF) 2735:(PDF) 2664:S2CID 2606:PeerJ 2572:S2CID 2539:S2CID 2483:(PDF) 2461:S2CID 2427:arXiv 2347:(PDF) 2324:(PDF) 2291:(PDF) 2280:S2CID 2246:arXiv 2232:(PDF) 2210:S2CID 2184:arXiv 2074:arXiv 2057:(PDF) 2042:(PDF) 1594:Notes 883:from 835:to 0. 751:words 392:is a 353:with 94:width 3167:PMID 2785:ISBN 2773:4288 2680:ISBN 2634:PMID 2465:2035 2453:PMID 2272:PMID 2154:PMID 2110:ISBN 2092:ISBN 1480:and 1355:Any 1308:The 864:Set 587:for 467:has 188:The 120:)). 118:1968 114:Wilf 39:, a 21:core 3159:doi 3135:doi 3131:143 3111:doi 3082:doi 3058:doi 3021:doi 2973:doi 2948:doi 2915:doi 2886:doi 2851:doi 2817:doi 2803:185 2777:doi 2749:doi 2712:doi 2700:314 2656:doi 2624:PMC 2614:doi 2564:doi 2529:doi 2497:doi 2445:doi 2393:doi 2361:doi 2264:doi 2242:286 2194:doi 2180:364 2144:PMC 2134:doi 2023:doi 2011:171 1463:mod 1320:of 1280:or 1161:of 906:of 786:in 660:in 337:is 306:is 277:of 254:of 104:or 35:In 3192:: 3173:, 3165:, 3153:, 3129:, 3105:, 3095:; 3076:, 3054:36 3042:; 3027:, 3017:68 3015:, 3009:, 2989:, 2983:MR 2981:, 2969:30 2967:, 2944:10 2942:, 2921:, 2911:29 2909:, 2905:, 2882:91 2880:, 2874:, 2847:22 2845:, 2823:, 2815:, 2801:, 2783:, 2745:25 2743:, 2737:, 2720:MR 2718:, 2710:, 2698:, 2662:, 2652:11 2650:, 2632:, 2622:, 2608:, 2570:, 2558:, 2537:, 2525:29 2523:, 2507:MR 2505:, 2493:17 2491:, 2485:, 2474:; 2459:, 2451:, 2443:, 2435:, 2423:96 2421:, 2401:MR 2399:, 2389:52 2377:; 2357:86 2355:, 2349:, 2328:MR 2313:; 2278:, 2270:, 2262:, 2254:, 2240:, 2234:, 2223:; 2208:, 2202:MR 2200:, 2192:, 2178:, 2152:, 2142:, 2128:, 2090:, 2082:, 2050:14 2048:, 2044:, 2021:, 2009:, 1929:; 1901:; 1897:; 1893:; 1889:; 1825:; 1809:; 1805:; 1785:; 1745:; 1705:, 1558:. 1352:. 1305:. 1273:. 1242:A 1231:a 1211:A 1134:. 849:, 573:. 561:, 384:A 92:, 3161:: 3155:5 3137:: 3113:: 3107:4 3084:: 3078:5 3060:: 3023:: 2975:: 2950:: 2917:: 2888:: 2867:k 2853:: 2837:k 2819:: 2809:: 2779:: 2751:: 2714:: 2706:: 2658:: 2616:: 2610:5 2602:k 2566:: 2560:7 2531:: 2499:: 2447:: 2439:: 2429:: 2413:k 2395:: 2363:: 2266:: 2258:: 2248:: 2196:: 2186:: 2136:: 2130:4 2086:: 2076:: 2066:k 2037:k 2025:: 2017:: 1969:. 1957:. 1945:. 1933:. 1917:. 1905:. 1877:. 1865:. 1853:. 1841:. 1829:. 1813:. 1793:. 1789:; 1773:. 1761:. 1731:G 1727:G 1723:G 1719:G 1715:G 1711:G 1693:. 1681:. 1669:. 1657:. 1645:. 1633:. 1621:. 1609:. 1541:G 1529:G 1500:3 1497:+ 1494:d 1488:n 1468:3 1459:0 1453:d 1431:3 1427:/ 1423:d 1419:3 1415:) 1412:d 1406:n 1403:( 1383:d 1363:n 1346:k 1342:k 1338:G 1330:n 1326:n 1322:G 1314:G 1298:k 1286:k 1267:k 1263:k 1259:k 1255:k 1251:k 1245:k 1237:k 1233:k 1217:k 1213:k 1198:k 1194:k 1187:k 1183:k 1179:n 1177:( 1175:k 1171:k 1167:n 1163:G 1152:k 1148:k 1144:G 1132:L 1118:l 1105:i 1091:] 1088:i 1085:, 1079:, 1076:1 1073:[ 1070:L 1050:G 1042:l 1038:H 1024:G 1020:l 1006:] 1003:1 997:i 994:, 988:, 985:1 982:[ 979:L 969:k 955:] 952:i 949:[ 946:L 932:. 929:w 927:d 923:w 918:w 916:d 912:L 908:v 904:w 899:. 897:D 893:L 889:v 885:D 881:v 876:) 874:i 872:, 870:k 866:k 859:D 855:i 851:D 847:D 840:n 833:k 828:. 826:i 821:v 819:d 815:L 811:v 807:D 803:D 796:L 792:v 788:G 784:v 779:v 777:d 772:. 770:L 759:k 738:) 735:| 732:V 729:| 726:( 721:O 699:) 696:| 693:E 690:| 687:+ 684:| 681:V 678:| 675:( 670:O 658:E 654:V 640:) 637:E 634:, 631:V 628:( 625:= 622:G 597:k 547:k 530:) 527:1 524:+ 521:c 518:( 498:c 478:c 455:u 442:k 438:G 434:k 430:G 426:k 422:G 418:k 414:k 410:G 402:k 398:G 390:G 386:k 378:k 367:k 363:k 359:k 347:G 343:k 339:k 335:G 328:v 324:v 320:k 316:v 312:k 308:k 304:G 300:H 296:H 292:H 283:k 279:G 271:k 263:G 256:G 248:G 240:G 224:k 220:k 213:m 209:m 205:m 201:m 156:k 152:k 146:k 141:k 127:k 122:k 88:k 72:k 68:k 60:k 56:k 42:k

Index

core

graph theory
undirected graph
degree
sparse
arboricity
Szekeres
Wilf
1968
linear time
connected components
forest
planar graph
outerplanar graph
Apollonian networks
Barabási–Albert model
random
scale-free networks
connected components
Erdős & Hajnal (1966)
chromatic number
Lick & White (1970)
induced subgraph
directed acyclic graph
outdegree
topological ordering
maximal
connected components
social networks

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