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Regular local ring

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is regular. (Zariski observed that this can fail over non-perfect fields.) This implies that smoothness is an intrinsic property of the variety, in other words it does not depend on where or how the variety is embedded in affine space. It also suggests that regular local rings should have good
1472: 2125:-module has a projective resolution of finite length. It is easy to show that the property of having finite global dimension is preserved under localization, and consequently that localizations of regular local rings at prime ideals are again regular. 741: 660: 2104:
Another property suggested by geometric intuition is that the localization of a regular local ring should again be regular. Again, this lay unsolved until the introduction of homological techniques. It was
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is regular. (The converse is always true: the multiplicity of a regular local ring is one.) This criterion corresponds to a geometric intuition in algebraic geometry that a local ring of an
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Herrmann, M., S. Ikeda, and U. Orbanz: Equimultiplicity and Blowing Up. An Algebraic Study with an Appendix by B. Moonen. Springer Verlag, Berlin Heidelberg New-York, 1988. Theorem 6.8.
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very little was known in this direction. Once such techniques were introduced in the 1950s, Auslander and Buchsbaum proved that every regular local ring is a
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is a regular local ring: that is, every such localization has the property that the minimal number of generators of its maximal ideal is equal to its
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is not a regular local ring since it is finite dimensional but does not have finite global dimension. For example, there is an infinite resolution
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is a regular local ring of dimension 1 and the regular local rings of dimension 1 are exactly the discrete valuation rings. Specifically, if
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global homological dimension. His definition is stronger than the definition above, which allows regular rings of infinite Krull dimension.
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but need not be an integral domain. For example, the product of two regular integral domains is regular, but not an integral domain.
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is a regular local ring. These have (Krull) dimension 0. In fact, the fields are exactly the regular local rings of dimension 0.
917: 152: 2554: 2187: 1500: 311: 1963: 1611: 1467:{\displaystyle \cdots {\xrightarrow {\cdot x}}{\frac {k}{(x^{2})}}{\xrightarrow {\cdot x}}{\frac {k}{(x^{2})}}\to k\to 0} 1230: 114: 2576: 260:
There are a number of useful definitions of a regular local ring, one of which is mentioned above. In particular, if
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is an example of a discrete valuation ring, and consequently a regular local ring, which does not contain a field.
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is unimixed (in the sense that there is no embedded prime divisor of the zero ideal and for each minimal prime
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a few years later, who showed that geometrically, a regular local ring corresponds to a smooth point on an
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Kunz, Characterizations of regular local rings of characteristic p. Amer. J. Math. 91 (1969), 772–784.
736:{\displaystyle {\mbox{gl dim }}A:=\sup\{\operatorname {pd} M\mid M{\text{ is an }}A{\text{-module}}\}} 2191: 283: 224: 2346:
A local von Neumann regular ring is a division ring, so the two conditions are not very compatible.
2141: 1765: 1249: 1002: 213: 1284: 1241: 1122: 230: 51: 419: 2238: 2160: 1813: 1761: 1078: 1926: 2602: 2529: 903: 768: 8: 2183: 2148: 2094: 1197: 1134: 1115: 67: 2446: 2247: 1694: 1674: 1654: 1560: 1480: 1237:) ) is an example of a 2-dimensional regular local ring which does not contain a field. 1084: 1030: 1008: 794: 774: 750: 570: 550: 393: 373: 263: 197: 2480: 2572: 2560: 2550: 2204: 2106: 1997: 1989: 145: 47: 2513: 2475: 2438: 2409: 2118: 2039: 1005:
case, there is the following important result due to Kunz: A Noetherian local ring
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who found a homological characterization of regular local rings: A local ring
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since a ring is reduced if and only if its localizations at prime ideals are.
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where the dimension is the Krull dimension. The minimal set of generators of
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For Noetherian local rings, there is the following chain of inclusions:
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be any Noetherian local ring with unique maximal ideal m, and suppose
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For the unrelated regular rings introduced by John von Neumann, see
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Examples of regular rings include fields (of dimension zero) and
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is a complete regular local ring that contains a field, then
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defined a regular ring as a commutative noetherian ring of
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for non-local commutative rings given in the next section.
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properties, but before the introduction of techniques from
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The concept is motivated by its geometric meaning. A point
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are indeterminates, then the ring of formal power series
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in 1937, but they first became prominent in the work of
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Any localization of a regular ring is regular as well.
1550:{\displaystyle {\mathfrak {m}}={\frac {(x)}{(x^{2})}}} 864: 825: 684: 2250: 1929: 1887: 1816: 1777: 1717: 1697: 1677: 1657: 1614: 1583: 1563: 1503: 1483: 1346: 1287: 1140:] is a regular local ring having (Krull) dimension 1. 1087: 1038: 1011: 920: 862: 823: 797: 777: 753: 682: 599: 573: 553: 515: 460: 422: 396: 376: 363:{\displaystyle {\mathfrak {m}}=(a_{1},\ldots ,a_{n})} 314: 286: 266: 165: 1644:{\displaystyle {\mathfrak {m}}/{\mathfrak {m}}^{2}} 1185:] is a regular local ring having (Krull) dimension 2291: 1947: 1911: 1869: 1799: 1733: 1703: 1683: 1663: 1643: 1600: 1569: 1549: 1489: 1466: 1329: 1196:is a regular local ring, then it follows that the 1093: 1069: 1017: 970: 887: 843: 803: 783: 759: 735: 654: 579: 559: 539: 492: 441: 402: 382: 362: 296: 272: 188: 304:, then the following are equivalent definitions: 2589: 994:is regular if and only if the intersection is a 696: 2508: 2375: 2197:For regular rings, Krull dimension agrees with 1980:Regular local rings were originally defined by 81:having the property that the minimal number of 844:{\displaystyle {\mbox{gl dim }}A<\infty \,} 280:is a Noetherian local ring with maximal ideal 2299:is regular. In the case of a field, this is 1477:Using another one of the characterizations, 730: 699: 2226:, with dimension one greater than that of 2012:is the vanishing locus of the polynomials 1969: 1753:states that every regular local ring is a 113:is a minimal set of generators of m. Then 2479: 1147:is an ordinary prime number, the ring of 840: 651: 438: 888:{\displaystyle {\mbox{gl dim }}A=\dim A} 2462: 2425: 2237:is a field, the ring of integers, or a 14: 2590: 1768:, of a regular local ring is regular. 1252:regular local ring of Krull dimension 1133:is an indeterminate, then the ring of 2396: 1070:{\displaystyle R\to R,r\mapsto r^{p}} 390:is chosen as small as possible. Then 255: 189:{\displaystyle {\mathcal {O}}_{X,x}} 26: 2583:Regular rings at The Stacks Project 2518:Introduction to Commutative Algebra 1912:{\displaystyle k=A/{\mathfrak {m}}} 1904: 1800:{\displaystyle (A,{\mathfrak {m}})} 1789: 1744: 1726: 1630: 1617: 1601:{\displaystyle {\mathfrak {m}}^{2}} 1587: 1506: 628: 615: 540:{\displaystyle k=A/{\mathfrak {m}}} 532: 493:{\displaystyle a_{1},\ldots ,a_{n}} 317: 289: 24: 1557:, so the ring has Krull dimension 837: 667:where the second dimension is the 169: 25: 2614: 2481:10.1090/s0002-9947-1947-0021694-1 2128:This justifies the definition of 2084:if and only if the local ring of 1734:{\displaystyle x+{\mathfrak {m}}} 1964:Serre's multiplicity conjectures 159:) if and only if the local ring 31: 2135: 1276: 297:{\displaystyle {\mathfrak {m}}} 115:Krull's principal ideal theorem 2487: 2456: 2419: 2390: 2381: 2349: 2340: 2286: 2254: 1864: 1861: 1829: 1826: 1794: 1778: 1541: 1528: 1523: 1517: 1458: 1452: 1446: 1433: 1428: 1422: 1395: 1382: 1377: 1371: 1324: 1311: 1303: 1297: 1215:is an indeterminate, the ring 1054: 1042: 1029:is regular if and only if the 357: 325: 13: 1: 2543:Lectures on Modules and Rings 2502: 2378:, p. 123, Theorem 11.22. 2362: 2199:global homological dimension 1960:Serre's inequality on height 1497:has exactly one prime ideal 1211:is the ring of integers and 502:regular system of parameters 7: 2376:Atiyah & Macdonald 1969 2316: 2099:unique factorization domain 1755:unique factorization domain 1751:Auslander–Buchsbaum theorem 1330:{\displaystyle A=k/(x^{2})} 1108: 1025:of positive characteristic 906:of a Noetherian local ring 767:(i.e., the supremum of the 243:complete intersection rings 208:.) Regular local rings are 40:It has been suggested that 10: 2619: 2494:Is a regular ring a domain 2323:Geometrically regular ring 2139: 2113:is regular if and only if 1973: 1691:. (In fact it is equal to 1260:is a power series ring in 900:Multiplicity one criterion 442:{\displaystyle \dim A=n\,} 225:Universally catenary rings 43:Geometrically regular ring 2192:ring of regular functions 2178:lies in the fact that an 1870:{\displaystyle A\cong k]} 214:von Neumann regular rings 57:Proposed since July 2024. 2333: 2301:Hilbert's syzygy theorem 2186:(that is every point is 2142:von Neumann regular ring 1948:{\displaystyle d=\dim A} 996:transversal intersection 547:be the residue field of 2468:Trans. Amer. Math. Soc. 2174:The origin of the term 2076:. Zariski proved that 1970:Origin of basic notions 1955:, the Krull dimension. 1233:in the prime ideal (2, 1123:discrete valuation ring 204:is regular. (See also: 2293: 2239:principal ideal domain 2222:is regular then so is 1949: 1913: 1871: 1801: 1735: 1705: 1685: 1665: 1645: 1608:is the zero ideal, so 1602: 1571: 1551: 1491: 1468: 1331: 1256:that contains a field 1095: 1071: 1019: 972: 889: 845: 805: 785: 761: 737: 656: 581: 561: 541: 494: 443: 404: 384: 364: 298: 274: 190: 2294: 2190:) if and only if its 1950: 1914: 1872: 1802: 1736: 1706: 1686: 1666: 1646: 1603: 1572: 1552: 1492: 1469: 1332: 1096: 1072: 1020: 973: 890: 846: 806: 786: 769:projective dimensions 762: 738: 657: 582: 562: 542: 495: 444: 405: 385: 365: 299: 275: 191: 2248: 2000:contained in affine 1927: 1885: 1814: 1775: 1715: 1695: 1675: 1655: 1612: 1581: 1561: 1501: 1481: 1344: 1285: 1085: 1036: 1009: 918: 860: 821: 795: 775: 751: 680: 597: 571: 551: 513: 458: 420: 394: 374: 312: 284: 264: 231:Cohen–Macaulay rings 163: 129:is regular whenever 50:into this article. ( 2149:commutative algebra 2095:homological algebra 2008:, and suppose that 1671:dimension at least 1413: 1362: 1204:] is regular local. 1198:formal power series 1154:More generally, if 1135:formal power series 249:regular local rings 68:commutative algebra 2598:Algebraic geometry 2510:Atiyah, Michael F. 2414:10.1007/BF01160110 2309:A regular ring is 2289: 2080:is nonsingular at 2040:Jacobian condition 2030:is nonsingular at 1945: 1909: 1867: 1797: 1731: 1701: 1681: 1661: 1641: 1598: 1567: 1547: 1487: 1464: 1327: 1264:variables over an 1091: 1067: 1031:Frobenius morphism 1015: 968: 885: 868: 841: 829: 801: 781: 757: 733: 688: 652: 577: 557: 537: 500:are then called a 490: 439: 400: 380: 360: 294: 270: 186: 93:. In symbols, let 72:regular local ring 2561:Jean-Pierre Serre 2555:978-1-4612-0525-8 2514:Macdonald, Ian G. 2292:{\displaystyle k} 2233:In particular if 2205:Jean-Pierre Serre 2155:is a commutative 2107:Jean-Pierre Serre 1998:algebraic variety 1990:algebraic variety 1764:, as well as the 1704:{\displaystyle 1} 1684:{\displaystyle 1} 1664:{\displaystyle k} 1570:{\displaystyle 0} 1545: 1490:{\displaystyle A} 1450: 1414: 1399: 1363: 1242:structure theorem 1094:{\displaystyle R} 1018:{\displaystyle R} 965: 936: 867: 828: 804:{\displaystyle A} 784:{\displaystyle A} 760:{\displaystyle A} 728: 720: 719: is an  687: 580:{\displaystyle A} 560:{\displaystyle A} 403:{\displaystyle A} 383:{\displaystyle n} 273:{\displaystyle A} 256:Characterizations 146:algebraic variety 64: 63: 59: 16:(Redirected from 2610: 2532: 2496: 2491: 2485: 2484: 2483: 2460: 2454: 2453: 2423: 2417: 2416: 2394: 2388: 2385: 2379: 2373: 2356: 2353: 2347: 2344: 2298: 2296: 2295: 2290: 2285: 2284: 2266: 2265: 2236: 2216:Dedekind domains 2159:, such that the 2121:, i.e. if every 2119:global dimension 1954: 1952: 1951: 1946: 1918: 1916: 1915: 1910: 1908: 1907: 1901: 1876: 1874: 1873: 1868: 1860: 1859: 1841: 1840: 1806: 1804: 1803: 1798: 1793: 1792: 1745:Basic properties 1740: 1738: 1737: 1732: 1730: 1729: 1710: 1708: 1707: 1702: 1690: 1688: 1687: 1682: 1670: 1668: 1667: 1662: 1650: 1648: 1647: 1642: 1640: 1639: 1634: 1633: 1626: 1621: 1620: 1607: 1605: 1604: 1599: 1597: 1596: 1591: 1590: 1576: 1574: 1573: 1568: 1556: 1554: 1553: 1548: 1546: 1544: 1540: 1539: 1526: 1515: 1510: 1509: 1496: 1494: 1493: 1488: 1473: 1471: 1470: 1465: 1451: 1449: 1445: 1444: 1431: 1417: 1415: 1402: 1400: 1398: 1394: 1393: 1380: 1366: 1364: 1351: 1336: 1334: 1333: 1328: 1323: 1322: 1310: 1100: 1098: 1097: 1092: 1076: 1074: 1073: 1068: 1066: 1065: 1024: 1022: 1021: 1016: 1001:In the positive 977: 975: 974: 969: 967: 966: 958: 943: 938: 937: 929: 894: 892: 891: 886: 869: 865: 850: 848: 847: 842: 830: 826: 810: 808: 807: 802: 791:-modules.) Then 790: 788: 787: 782: 766: 764: 763: 758: 745:global dimension 742: 740: 739: 734: 729: 726: 721: 718: 689: 685: 661: 659: 658: 653: 638: 637: 632: 631: 624: 619: 618: 609: 608: 586: 584: 583: 578: 566: 564: 563: 558: 546: 544: 543: 538: 536: 535: 529: 499: 497: 496: 491: 489: 488: 470: 469: 448: 446: 445: 440: 409: 407: 406: 401: 389: 387: 386: 381: 369: 367: 366: 361: 356: 355: 337: 336: 321: 320: 303: 301: 300: 295: 293: 292: 279: 277: 276: 271: 237:Gorenstein rings 195: 193: 192: 187: 185: 184: 173: 172: 89:is equal to its 55: 35: 34: 27: 21: 2618: 2617: 2613: 2612: 2611: 2609: 2608: 2607: 2588: 2587: 2569:Springer-Verlag 2547:Springer-Verlag 2505: 2500: 2499: 2492: 2488: 2461: 2457: 2443:10.2307/2371447 2424: 2420: 2398:Krull, Wolfgang 2395: 2391: 2386: 2382: 2374: 2370: 2365: 2360: 2359: 2354: 2350: 2345: 2341: 2336: 2328:quasi-free ring 2319: 2280: 2276: 2261: 2257: 2249: 2246: 2245: 2243:polynomial ring 2234: 2169:Krull dimension 2157:Noetherian ring 2145: 2138: 2058: 2051: 2024: 2017: 1978: 1972: 1928: 1925: 1924: 1903: 1902: 1897: 1886: 1883: 1882: 1855: 1851: 1836: 1832: 1815: 1812: 1811: 1788: 1787: 1776: 1773: 1772: 1747: 1725: 1724: 1716: 1713: 1712: 1696: 1693: 1692: 1676: 1673: 1672: 1656: 1653: 1652: 1635: 1629: 1628: 1627: 1622: 1616: 1615: 1613: 1610: 1609: 1592: 1586: 1585: 1584: 1582: 1579: 1578: 1562: 1559: 1558: 1535: 1531: 1527: 1516: 1514: 1505: 1504: 1502: 1499: 1498: 1482: 1479: 1478: 1440: 1436: 1432: 1418: 1416: 1401: 1389: 1385: 1381: 1367: 1365: 1350: 1345: 1342: 1341: 1318: 1314: 1306: 1286: 1283: 1282: 1279: 1266:extension field 1226:(i.e. the ring 1225: 1180: 1171: 1164: 1158:is a field and 1149:p-adic integers 1129:is a field and 1111: 1086: 1083: 1082: 1061: 1057: 1037: 1034: 1033: 1010: 1007: 1006: 957: 956: 939: 928: 927: 919: 916: 915: 902:states: if the 863: 861: 858: 857: 856:in which case, 824: 822: 819: 818: 796: 793: 792: 776: 773: 772: 752: 749: 748: 725: 717: 683: 681: 678: 677: 669:Krull dimension 633: 627: 626: 625: 620: 614: 613: 604: 600: 598: 595: 594: 572: 569: 568: 552: 549: 548: 531: 530: 525: 514: 511: 510: 484: 480: 465: 461: 459: 456: 455: 421: 418: 417: 395: 392: 391: 375: 372: 371: 351: 347: 332: 328: 316: 315: 313: 310: 309: 288: 287: 285: 282: 281: 265: 262: 261: 258: 174: 168: 167: 166: 164: 161: 160: 112: 103: 91:Krull dimension 60: 36: 32: 23: 22: 15: 12: 11: 5: 2616: 2606: 2605: 2600: 2586: 2585: 2580: 2558: 2536: 2533: 2522:Addison-Wesley 2504: 2501: 2498: 2497: 2486: 2464:Zariski, Oscar 2455: 2431:Amer. J. Math. 2427:Zariski, Oscar 2418: 2389: 2380: 2367: 2366: 2364: 2361: 2358: 2357: 2348: 2338: 2337: 2335: 2332: 2331: 2330: 2325: 2318: 2315: 2288: 2283: 2279: 2275: 2272: 2269: 2264: 2260: 2256: 2253: 2180:affine variety 2137: 2134: 2056: 2049: 2022: 2015: 2004:-space over a 1982:Wolfgang Krull 1971: 1968: 1944: 1941: 1938: 1935: 1932: 1906: 1900: 1896: 1893: 1890: 1879: 1878: 1866: 1863: 1858: 1854: 1850: 1847: 1844: 1839: 1835: 1831: 1828: 1825: 1822: 1819: 1796: 1791: 1786: 1783: 1780: 1746: 1743: 1728: 1723: 1720: 1700: 1680: 1660: 1638: 1632: 1625: 1619: 1595: 1589: 1566: 1543: 1538: 1534: 1530: 1525: 1522: 1519: 1513: 1508: 1486: 1475: 1474: 1463: 1460: 1457: 1454: 1448: 1443: 1439: 1435: 1430: 1427: 1424: 1421: 1412: 1409: 1405: 1397: 1392: 1388: 1384: 1379: 1376: 1373: 1370: 1361: 1358: 1354: 1349: 1326: 1321: 1317: 1313: 1309: 1305: 1302: 1299: 1296: 1293: 1290: 1278: 1275: 1274: 1273: 1238: 1219: 1205: 1190: 1176: 1169: 1162: 1152: 1141: 1119: 1110: 1107: 1090: 1064: 1060: 1056: 1053: 1050: 1047: 1044: 1041: 1014: 1003:characteristic 964: 961: 955: 952: 949: 946: 942: 935: 932: 926: 923: 897: 896: 884: 881: 878: 875: 872: 854: 853: 852: 839: 836: 833: 813: 812: 800: 780: 756: 732: 724: 716: 713: 710: 707: 704: 701: 698: 695: 692: 673: 672: 665: 664: 663: 650: 647: 644: 641: 636: 630: 623: 617: 612: 607: 603: 589: 588: 576: 556: 534: 528: 524: 521: 518: 506: 505: 487: 483: 479: 476: 473: 468: 464: 452: 451: 450: 437: 434: 431: 428: 425: 412: 411: 399: 379: 359: 354: 350: 346: 343: 340: 335: 331: 327: 324: 319: 291: 269: 257: 254: 253: 252: 206:regular scheme 183: 180: 177: 171: 108: 101: 62: 61: 39: 37: 30: 9: 6: 4: 3: 2: 2615: 2604: 2601: 2599: 2596: 2595: 2593: 2584: 2581: 2579:. Chap.IV.D. 2578: 2577:3-540-66641-9 2574: 2570: 2566: 2565:Local algebra 2562: 2559: 2556: 2552: 2548: 2544: 2540: 2539:Tsit-Yuen Lam 2537: 2534: 2531: 2527: 2523: 2519: 2515: 2511: 2507: 2506: 2495: 2490: 2482: 2477: 2473: 2469: 2465: 2459: 2452: 2448: 2444: 2440: 2436: 2432: 2428: 2422: 2415: 2411: 2407: 2403: 2399: 2393: 2384: 2377: 2372: 2368: 2352: 2343: 2339: 2329: 2326: 2324: 2321: 2320: 2314: 2312: 2307: 2304: 2302: 2281: 2277: 2273: 2270: 2267: 2262: 2258: 2251: 2244: 2240: 2231: 2229: 2225: 2221: 2217: 2212: 2210: 2206: 2202: 2200: 2195: 2193: 2189: 2185: 2181: 2177: 2172: 2170: 2166: 2162: 2158: 2154: 2150: 2143: 2133: 2131: 2126: 2124: 2120: 2116: 2112: 2108: 2102: 2100: 2096: 2091: 2087: 2083: 2079: 2075: 2071: 2067: 2063: 2059: 2052: 2045: 2041: 2037: 2033: 2029: 2025: 2018: 2011: 2007: 2006:perfect field 2003: 1999: 1995: 1991: 1987: 1986:Oscar Zariski 1983: 1977: 1976:smooth scheme 1967: 1965: 1961: 1956: 1942: 1939: 1936: 1933: 1930: 1922: 1921:residue field 1898: 1894: 1891: 1888: 1856: 1852: 1848: 1845: 1842: 1837: 1833: 1823: 1820: 1817: 1810: 1809: 1808: 1784: 1781: 1769: 1767: 1763: 1758: 1756: 1752: 1742: 1741:is a basis.) 1721: 1718: 1698: 1678: 1658: 1636: 1623: 1593: 1564: 1536: 1532: 1520: 1511: 1484: 1461: 1455: 1441: 1437: 1425: 1419: 1410: 1407: 1403: 1390: 1386: 1374: 1368: 1359: 1356: 1352: 1347: 1340: 1339: 1338: 1319: 1315: 1307: 1300: 1294: 1291: 1288: 1271: 1267: 1263: 1259: 1255: 1251: 1247: 1243: 1239: 1236: 1232: 1229: 1223: 1218: 1214: 1210: 1206: 1203: 1199: 1195: 1191: 1188: 1184: 1179: 1175: 1168: 1161: 1157: 1153: 1150: 1146: 1142: 1139: 1136: 1132: 1128: 1124: 1120: 1117: 1113: 1112: 1106: 1104: 1088: 1080: 1062: 1058: 1051: 1048: 1045: 1039: 1032: 1028: 1012: 1004: 999: 997: 993: 989: 986:is one, then 985: 981: 978:) and if the 962: 959: 953: 950: 947: 944: 940: 933: 930: 924: 921: 913: 909: 905: 901: 882: 879: 876: 873: 870: 855: 834: 831: 817: 816: 815: 814: 811:is regular if 798: 778: 770: 754: 746: 722: 714: 711: 708: 705: 702: 693: 690: 675: 674: 670: 666: 648: 645: 642: 639: 634: 621: 610: 605: 601: 593: 592: 591: 590: 587:is regular if 574: 554: 526: 522: 519: 516: 508: 507: 503: 485: 481: 477: 474: 471: 466: 462: 453: 435: 432: 429: 426: 423: 416: 415: 414: 413: 410:is regular if 397: 377: 352: 348: 344: 341: 338: 333: 329: 322: 307: 306: 305: 267: 251: 250: 245: 244: 239: 238: 233: 232: 227: 226: 222: 221: 220: 217: 215: 211: 207: 203: 199: 181: 178: 175: 158: 154: 150: 147: 143: 138: 136: 132: 128: 124: 120: 117:implies that 116: 111: 107: 100: 96: 92: 88: 87:maximal ideal 84: 80: 77: 73: 69: 58: 53: 49: 45: 44: 38: 29: 28: 19: 2564: 2557:. Chap.5.G. 2542: 2517: 2489: 2471: 2467: 2458: 2434: 2430: 2421: 2405: 2401: 2392: 2383: 2371: 2351: 2342: 2308: 2305: 2232: 2227: 2223: 2219: 2213: 2208: 2203: 2196: 2194:is regular. 2176:regular ring 2175: 2173: 2161:localization 2153:regular ring 2152: 2146: 2136:Regular ring 2129: 2127: 2122: 2114: 2110: 2103: 2089: 2085: 2081: 2077: 2073: 2072:− dim 2069: 2065: 2061: 2054: 2047: 2043: 2038:satisfies a 2035: 2031: 2027: 2020: 2013: 2009: 2001: 1993: 1979: 1957: 1880: 1770: 1762:localization 1759: 1748: 1476: 1280: 1277:Non-examples 1269: 1261: 1257: 1253: 1234: 1227: 1221: 1216: 1212: 1208: 1201: 1193: 1186: 1182: 1177: 1173: 1166: 1159: 1155: 1144: 1137: 1130: 1126: 1026: 1000: 992:intersection 987: 983: 980:multiplicity 911: 907: 899: 898: 866:gl dim  827:gl dim  686:gl dim  501: 259: 248: 247: 241: 235: 229: 223: 218: 209: 201: 157:smooth point 148: 141: 139: 134: 130: 126: 122: 118: 109: 105: 98: 94: 71: 65: 56: 41: 18:Regular ring 2603:Ring theory 2437:: 187–221, 2408:: 745–766, 2241:, then the 2184:nonsingular 2165:prime ideal 2117:has finite 1246:Irvin Cohen 212:related to 153:nonsingular 2592:Categories 2503:References 2130:regularity 1974:See also: 1958:See also: 1766:completion 904:completion 83:generators 79:local ring 76:Noetherian 2363:Citations 2271:… 2163:at every 1940:⁡ 1846:… 1821:≅ 1459:→ 1453:→ 1408:⋅ 1357:⋅ 1348:⋯ 1281:The ring 1231:localized 1055:↦ 1043:→ 963:^ 954:⁡ 934:^ 925:⁡ 880:⁡ 838:∞ 712:∣ 706:⁡ 646:⁡ 611:⁡ 475:… 427:⁡ 342:… 2571:, 2000, 2549:, 1999, 2516:(1969), 2474:: 1–52, 2402:Math. Z. 2317:See also 1404:→ 1353:→ 1250:complete 1109:Examples 2530:0242802 2451:2371447 2311:reduced 2188:regular 1992:. Let 1919:is the 1240:By the 1172:, ..., 1103:reduced 771:of all 743:be the 727:-module 567:. Then 104:, ..., 85:of its 52:Discuss 2575:  2553:  2528:  2449:  2218:. If 2209:finite 1996:be an 1923:, and 1881:where 1760:Every 1711:since 1577:, but 1114:Every 370:where 144:on an 133:= dim 125:, and 121:≄ dim 48:merged 2447:JSTOR 2334:Notes 2042:: If 2019:,..., 1200:ring 1116:field 198:germs 74:is a 2573:ISBN 2551:ISBN 2151:, a 2046:= (∂ 1962:and 1749:The 1651:has 1248:, a 1220:(2, 1121:Any 1081:and 1079:flat 835:< 676:Let 509:Let 308:Let 70:, a 2476:doi 2439:doi 2410:doi 2230:. 2182:is 2147:In 2088:at 2068:is 2064:at 2034:if 2026:. 1937:dim 1771:If 1268:of 1244:of 1207:If 1192:If 1143:If 1101:is 1077:is 982:of 951:dim 922:dim 877:dim 747:of 697:sup 643:dim 602:dim 424:dim 228:⊃ 210:not 200:at 196:of 155:(a 151:is 66:In 46:be 2594:: 2567:, 2563:, 2545:, 2541:, 2526:MR 2524:, 2520:, 2512:; 2472:62 2470:, 2445:, 2435:62 2433:, 2406:42 2404:, 2303:. 2201:. 2171:. 2101:. 2053:/∂ 1966:. 1757:. 1165:, 998:. 914:, 703:pd 694::= 246:⊃ 240:⊃ 234:⊃ 216:. 137:. 2478:: 2441:: 2412:: 2287:] 2282:n 2278:X 2274:, 2268:, 2263:1 2259:X 2255:[ 2252:k 2235:k 2228:A 2224:A 2220:A 2144:. 2123:A 2115:A 2111:A 2090:P 2086:Y 2082:P 2078:Y 2074:Y 2070:n 2066:P 2062:M 2057:j 2055:x 2050:i 2048:f 2044:M 2036:Y 2032:P 2028:Y 2023:m 2021:f 2016:1 2014:f 2010:Y 2002:n 1994:Y 1943:A 1934:= 1931:d 1905:m 1899:/ 1895:A 1892:= 1889:k 1877:, 1865:] 1862:] 1857:d 1853:x 1849:, 1843:, 1838:1 1834:x 1830:[ 1827:[ 1824:k 1818:A 1795:) 1790:m 1785:, 1782:A 1779:( 1727:m 1722:+ 1719:x 1699:1 1679:1 1659:k 1637:2 1631:m 1624:/ 1618:m 1594:2 1588:m 1565:0 1542:) 1537:2 1533:x 1529:( 1524:) 1521:x 1518:( 1512:= 1507:m 1485:A 1462:0 1456:k 1447:) 1442:2 1438:x 1434:( 1429:] 1426:x 1423:[ 1420:k 1411:x 1396:) 1391:2 1387:x 1383:( 1378:] 1375:x 1372:[ 1369:k 1360:x 1325:) 1320:2 1316:x 1312:( 1308:/ 1304:] 1301:x 1298:[ 1295:k 1292:= 1289:A 1272:. 1270:k 1262:d 1258:k 1254:d 1235:X 1228:Z 1224:) 1222:X 1217:Z 1213:X 1209:Z 1202:A 1194:A 1189:. 1187:d 1183:k 1178:d 1174:X 1170:2 1167:X 1163:1 1160:X 1156:k 1145:p 1138:k 1131:X 1127:k 1089:R 1063:p 1059:r 1052:r 1049:, 1046:R 1040:R 1027:p 1013:R 988:A 984:A 960:A 948:= 945:p 941:/ 931:A 912:p 908:A 895:. 883:A 874:= 871:A 851:, 832:A 799:A 779:A 755:A 731:} 723:A 715:M 709:M 700:{ 691:A 671:. 662:, 649:A 640:= 635:2 629:m 622:/ 616:m 606:k 575:A 555:A 533:m 527:/ 523:A 520:= 517:k 504:. 486:n 482:a 478:, 472:, 467:1 463:a 449:, 436:n 433:= 430:A 398:A 378:n 358:) 353:n 349:a 345:, 339:, 334:1 330:a 326:( 323:= 318:m 290:m 268:A 202:x 182:x 179:, 176:X 170:O 149:X 142:x 135:A 131:n 127:A 123:A 119:n 110:n 106:a 102:1 99:a 95:A 54:) 20:)

Index

Regular ring
Geometrically regular ring
merged
Discuss
commutative algebra
Noetherian
local ring
generators
maximal ideal
Krull dimension
Krull's principal ideal theorem
algebraic variety
nonsingular
smooth point
germs
regular scheme
von Neumann regular rings
Universally catenary rings
Cohen–Macaulay rings
Gorenstein rings
complete intersection rings
regular local rings
Krull dimension
global dimension
projective dimensions
completion
multiplicity
intersection
transversal intersection
characteristic

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