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Multiplicity theory

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As Hilbert–Poincaré series are additive on exact sequences, the multiplicity is additive on exact sequences of modules of the same dimension.
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The following theorem, due to Christer Lech, gives a priori bounds for multiplicity.
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The notion of the multiplicity of a module is a generalization of the
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Integral Closure: Rees Algebras, Multiplicities, Algorithms
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The main focus of the theory is to detect and measure a
766:. Springer Science & Business Media. p. 129. 85:. By Serre's intersection formula, it is linked to an 633: 606: 578: 511: 471: 351: 296: 260: 195: 43: 283:
is a polynomial. By definition, the multiplicity of
702: 616: 588: 544: 498:are the coefficients of the Hilbert polynomial of 490: 446: 331: 275: 243: 70: 186:. This series is a rational function of the form 116:are intimately connected to multiplicity theory. 826: 759: 502:expanded in binomial coefficients. We have 119: 244:{\displaystyle {\frac {P(t)}{(1-t)^{d}}},} 812: 827: 545:{\displaystyle \mathbf {e} (M)=a_{0}.} 128:be a positively graded ring such that 98:singular point of an algebraic variety 332:{\displaystyle \mathbf {e} (M)=P(1).} 786: 71:{\displaystyle \mathbf {e} _{I}(M).} 609: 581: 13: 760:Vasconcelos, Wolmer (2006-03-30). 14: 846: 789:"Note on multiplicity of ideals" 513: 298: 46: 617:{\displaystyle {\mathfrak {m}}} 589:{\displaystyle {\mathfrak {m}}} 780: 753: 694: 673: 667: 661: 643: 637: 523: 517: 438: 432: 414: 401: 361: 355: 323: 317: 308: 302: 270: 264: 226: 213: 208: 202: 83:degree of a projective variety 62: 56: 1: 746: 465:) is a polynomial. Note that 342:The series may be rewritten 689: 572:is local with maximal ideal 132:is finitely generated as an 7: 731:Hilbert–Samuel multiplicity 714: 104:). Because of this aspect, 102:resolution of singularities 10: 851: 721:Dimension theory (algebra) 87:intersection multiplicity 165:be a finitely generated 120:Multiplicity of a module 34:(often a maximal ideal) 22:multiplicity of a module 835:Theorems in ring theory 491:{\displaystyle a_{d-i}} 184:Hilbert–PoincarĂ© series 704: 618: 590: 546: 492: 448: 381: 333: 277: 245: 72: 736:Hilbert–Kunz function 705: 624:-primary ideal, then 619: 591: 547: 493: 449: 367: 334: 278: 246: 73: 16:In abstract algebra, 631: 604: 576: 509: 469: 349: 294: 276:{\displaystyle P(t)} 258: 193: 41: 805:1960ArM.....4...63L 793:Arkiv för Matematik 566: —  91:intersection theory 18:multiplicity theory 814:10.1007/BF02591323 741:Normally flat ring 700: 614: 586: 564: 542: 488: 444: 329: 273: 241: 68: 787:Lech, C. (1960). 692: 562: 424: 236: 842: 819: 818: 816: 784: 778: 777: 757: 709: 707: 706: 701: 693: 685: 683: 623: 621: 620: 615: 613: 612: 595: 593: 592: 587: 585: 584: 567: 551: 549: 548: 543: 538: 537: 516: 497: 495: 494: 489: 487: 486: 453: 451: 450: 445: 425: 423: 422: 421: 399: 398: 383: 380: 375: 338: 336: 335: 330: 301: 282: 280: 279: 274: 250: 248: 247: 242: 237: 235: 234: 233: 211: 197: 114:integral closure 106:valuation theory 77: 75: 74: 69: 55: 54: 49: 850: 849: 845: 844: 843: 841: 840: 839: 825: 824: 823: 822: 785: 781: 774: 758: 754: 749: 717: 712: 684: 679: 632: 629: 628: 608: 607: 605: 602: 601: 580: 579: 577: 574: 573: 565: 533: 529: 512: 510: 507: 506: 476: 472: 470: 467: 466: 417: 413: 400: 388: 384: 382: 376: 371: 350: 347: 346: 297: 295: 292: 291: 259: 256: 255: 229: 225: 212: 198: 196: 194: 191: 190: 177: 156:Krull dimension 145: 138: 122: 50: 45: 44: 42: 39: 38: 12: 11: 5: 848: 838: 837: 821: 820: 779: 772: 751: 750: 748: 745: 744: 743: 738: 733: 728: 726:j-multiplicity 723: 716: 713: 711: 710: 699: 696: 691: 688: 682: 678: 675: 672: 669: 666: 663: 660: 657: 654: 651: 648: 645: 642: 639: 636: 611: 583: 560: 553: 552: 541: 536: 532: 528: 525: 522: 519: 515: 485: 482: 479: 475: 455: 454: 443: 440: 437: 434: 431: 428: 420: 416: 412: 409: 406: 403: 397: 394: 391: 387: 379: 374: 370: 366: 363: 360: 357: 354: 340: 339: 328: 325: 322: 319: 316: 313: 310: 307: 304: 300: 272: 269: 266: 263: 252: 251: 240: 232: 228: 224: 221: 218: 215: 210: 207: 204: 201: 173: 143: 136: 121: 118: 79: 78: 67: 64: 61: 58: 53: 48: 9: 6: 4: 3: 2: 847: 836: 833: 832: 830: 815: 810: 806: 802: 798: 794: 790: 783: 775: 773:9783540265030 769: 765: 764: 756: 752: 742: 739: 737: 734: 732: 729: 727: 724: 722: 719: 718: 697: 686: 680: 676: 670: 664: 658: 655: 652: 649: 646: 640: 634: 627: 626: 625: 599: 571: 559: 556: 539: 534: 530: 526: 520: 505: 504: 503: 501: 483: 480: 477: 473: 464: 460: 441: 435: 429: 426: 418: 410: 407: 404: 395: 392: 389: 385: 377: 372: 368: 364: 358: 352: 345: 344: 343: 326: 320: 314: 311: 305: 290: 289: 288: 286: 267: 261: 238: 230: 222: 219: 216: 205: 199: 189: 188: 187: 185: 181: 176: 172: 168: 164: 160: 157: 153: 149: 142: 139:-algebra and 135: 131: 127: 117: 115: 111: 110:Rees algebras 107: 103: 99: 94: 92: 88: 84: 65: 59: 51: 37: 36: 35: 33: 30: 26: 23: 20:concerns the 19: 799:(1): 63–86. 796: 792: 782: 762: 755: 597: 569: 561: 557: 554: 499: 462: 458: 456: 341: 284: 253: 179: 174: 170: 169:-module and 166: 162: 158: 151: 150:. Note that 140: 133: 129: 125: 123: 95: 80: 31: 24: 21: 17: 15: 154:has finite 747:References 690:¯ 671:λ 659:⁡ 647:≤ 481:− 408:− 393:− 369:∑ 220:− 829:Category 715:See also 596:. If an 568:Suppose 148:Artinian 801:Bibcode 89:in the 770:  457:where 254:where 182:) its 161:. Let 27:at an 100:(cf. 29:ideal 768:ISBN 563:Lech 287:is 124:Let 112:and 809:doi 656:deg 600:is 146:is 831:: 807:. 795:. 791:. 108:, 93:. 817:. 811:: 803:: 797:4 776:. 698:. 695:) 687:I 681:/ 677:R 674:( 668:) 665:R 662:( 653:! 650:d 644:) 641:I 638:( 635:e 610:m 598:I 582:m 570:R 540:. 535:0 531:a 527:= 524:) 521:M 518:( 514:e 500:M 484:i 478:d 474:a 463:t 461:( 459:r 442:. 439:) 436:t 433:( 430:r 427:+ 419:d 415:) 411:t 405:1 402:( 396:i 390:d 386:a 378:d 373:1 365:= 362:) 359:t 356:( 353:F 327:. 324:) 321:1 318:( 315:P 312:= 309:) 306:M 303:( 299:e 285:M 271:) 268:t 265:( 262:P 239:, 231:d 227:) 223:t 217:1 214:( 209:) 206:t 203:( 200:P 180:t 178:( 175:M 171:F 167:R 163:M 159:d 152:R 144:0 141:R 137:0 134:R 130:R 126:R 66:. 63:) 60:M 57:( 52:I 47:e 32:I 25:M

Index

ideal
degree of a projective variety
intersection multiplicity
intersection theory
singular point of an algebraic variety
resolution of singularities
valuation theory
Rees algebras
integral closure
Artinian
Krull dimension
Hilbert–Poincaré series
Dimension theory (algebra)
j-multiplicity
Hilbert–Samuel multiplicity
Hilbert–Kunz function
Normally flat ring
Integral Closure: Rees Algebras, Multiplicities, Algorithms
ISBN
9783540265030
"Note on multiplicity of ideals"
Bibcode
1960ArM.....4...63L
doi
10.1007/BF02591323
Category
Theorems in ring theory

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