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Conductor of an elliptic curve

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106:, analogous to the way the conductor of a global field appears in the functional equation of its zeta function. He showed that it could be written as a product over primes with exponents given by order(Δ) − ÎŒ + 1, which by Ogg's formula is equal to Δ+ÎŽ. A similar definition works for any global field. Weil also suggested that the conductor was equal to the level of a modular form corresponding to the elliptic curve. 192:
of the conductor as a sum Δ + Ύ of two terms, corresponding to the tame and wild ramification. The tame ramification part Δ is defined in terms of the reduction type: Δ=0 for good reduction, Δ=1 for multiplicative reduction and Δ=2 for additive reduction. The wild ramification term Ύ is zero unless
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This is a finite product as the primes of bad reduction are contained in the set of primes divisors of the discriminant of any model for
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The exponent of the conductor is related to other invariants of the elliptic curve by Ogg's formula:
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in the form of an integer invariant Δ+Ύ which later turned out to be the exponent of the conductor.
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Saito, Takeshi (1988), "Conductor, discriminant, and the Noether formula of arithmetic surfaces",
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and the number of components of the special fiber over a local field, which can be computed using
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Ogg's original proof used a lot of case by case checking, especially in characteristics 2 and 3.
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The conductor of an elliptic curve over a local field was implicitly studied (but not named) by
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Weil, AndrĂ© (1967), "Über die Bestimmung Dirichletscher Reihen durch Funktionalgleichungen",
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is the number of components (without counting multiplicities) of the singular fibre of the
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gave a uniform proof and generalized Ogg's formula to more general arithmetic surfaces.
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The conductor of an elliptic curve over the rationals was introduced and named by
957: 827: 774: 738: 673: 53: 37: 21: 206: 61: 996: 815: 726: 669: 65: 575:{\displaystyle f(E)=\prod _{\mathbf {p} }\mathbf {p} ^{f_{\mathbf {p} }}\ .} 76: 29: 644:"ModĂšles minimaux des variĂ©tĂ©s abĂ©liennes sur les corps locaux et globaux" 624:. Graduate Texts in Mathematics. Vol. 111 (2nd ed.). Springer. 505:. The global conductor is the ideal given by the product over primes of 456: 129: 45: 25: 982: 953: 916: 823: 734: 700: 661: 197:
divides 2 or 3, and in the latter cases it is defined in terms of the
807: 718: 427:{\displaystyle f_{\mathbf {p} }=\nu _{\mathbf {p} }(\Delta )+1-n\ ,} 64:. The primes involved in the conductor are precisely the primes of 445:
for E. (This is sometimes used as a definition of the conductor).
853:. Graduate Texts in Mathematics. Vol. 151. Springer-Verlag. 469:): it is 0 in the case of good reduction; otherwise it is 1 if Îœ 898: 302:{\displaystyle \delta =\dim _{Z/lZ}{\text{Hom}}_{Z_{l}}(P,M).} 102:
as a constant appearing in the functional equation of its
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We can also describe Δ in terms of the valuation of the
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is the group of points on the elliptic curve of order
163:-integral and with the valuation of the discriminant Μ 75:
Ogg's formula expresses the conductor in terms of the
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Advanced Topics in the Arithmetic of Elliptic Curves
169:(Δ) as small as possible. If the discriminant is a 574: 426: 301: 703:(1967), "Elliptic curves and wild ramification", 501:be an elliptic curve defined over a number field 994: 792:(1968), "Good reduction of abelian varieties", 56:generated by the points of finite order in the 989:listed by conductor, computed by John Cremona 867: 605:(2nd ed.). Cambridge University Press. 185:and the exponent of the conductor is zero. 619: 336:the Galois group of a finite extension of 893: 845: 784: 109: 598: 995: 602:Algorithms for Modular Elliptic Curves 756: 638: 449: 939: 649:Publications MathĂ©matiques de l'IHÉS 128:be an elliptic curve defined over a 99: 899:"The arithmetic of elliptic curves" 699: 589:with global integral coefficients. 492: 92: 13: 877:Rational Points on Elliptic Curves 400: 14: 1014: 985:- tables of elliptic curves over 976: 558: 547: 539: 391: 376: 355: 706:American Journal of Mathematics 114:conductors of abelian varieties 70:NĂ©ron–Ogg–Shafarevich criterion 527: 521: 403: 397: 293: 281: 276: 270: 44:. It is given as a product of 18:conductor of an elliptic curve 1: 771:10.1215/S0012-7094-88-05706-7 592: 344:are defined over it (so that 119: 36:, which is analogous to the 7: 10: 1019: 188:We can write the exponent 86: 68:of the curve: this is the 620:Husemöller, Dale (2004). 904:Inventiones Mathematicae 340:such that the points of 159:whose coefficients are 112:extended the theory to 110:Serre & Tate (1968) 599:Cremona, John (1997). 576: 428: 303: 795:Annals of Mathematics 577: 429: 304: 201:of the extensions of 139:a prime ideal of the 42:Galois representation 24:(or more generally a 869:Silverman, Joseph H. 847:Silverman, Joseph H. 515: 367: 220: 157:Weierstrass equation 16:In mathematics, the 983:Elliptic Curve Data 879:. Springer-Verlag. 479:) < 0 and 2 if Îœ 443:NĂ©ron minimal model 330:Swan representation 213:by Serre's formula 954:10.1007/BF01361551 917:10.1007/BF01389745 786:Serre, Jean-Pierre 662:10.1007/BF02684271 572: 544: 424: 299: 20:over the field of 798:, Second Series, 568: 533: 420: 257: 199:wild ramification 147:. We consider a 32:) is an integral 1010: 972: 936: 911:(3–4): 179–206. 890: 864: 842: 781: 753: 696: 635: 616: 581: 579: 578: 573: 566: 565: 564: 563: 562: 561: 550: 543: 542: 493:Global conductor 433: 431: 430: 425: 418: 396: 395: 394: 381: 380: 379: 308: 306: 305: 300: 280: 279: 269: 268: 258: 255: 249: 248: 241: 155:: a generalised 149:minimal equation 141:ring of integers 81:Tate's algorithm 54:field extensions 22:rational numbers 1018: 1017: 1013: 1012: 1011: 1009: 1008: 1007: 1003:Elliptic curves 993: 992: 979: 887: 861: 808:10.2307/1970722 719:10.2307/2373092 632: 622:Elliptic Curves 613: 595: 557: 556: 552: 551: 546: 545: 538: 537: 516: 513: 512: 495: 484: 474: 464: 390: 389: 385: 375: 374: 370: 368: 365: 364: 358: 264: 260: 259: 254: 253: 237: 233: 229: 221: 218: 217: 207:division points 168: 122: 89: 38:Artin conductor 12: 11: 5: 1016: 1006: 1005: 991: 990: 978: 977:External links 975: 974: 973: 937: 891: 885: 865: 859: 843: 802:(3): 492–517, 782: 765:(1): 151–173, 754: 697: 636: 630: 617: 611: 594: 591: 583: 582: 571: 560: 555: 549: 541: 536: 532: 529: 526: 523: 520: 494: 491: 480: 470: 460: 435: 434: 423: 417: 414: 411: 408: 405: 402: 399: 393: 388: 384: 378: 373: 357: 354: 310: 309: 298: 295: 292: 289: 286: 283: 278: 275: 272: 267: 263: 252: 247: 244: 240: 236: 232: 228: 225: 179:good reduction 164: 121: 118: 88: 85: 62:elliptic curve 9: 6: 4: 3: 2: 1015: 1004: 1001: 1000: 998: 988: 984: 981: 980: 971: 967: 963: 959: 955: 951: 947: 943: 938: 934: 930: 926: 922: 918: 914: 910: 906: 905: 900: 896: 892: 888: 886:0-387-97825-9 882: 878: 874: 870: 866: 862: 860:0-387-94328-5 856: 852: 848: 844: 841: 837: 833: 829: 825: 821: 817: 813: 809: 805: 801: 797: 796: 791: 787: 783: 780: 776: 772: 768: 764: 760: 759:Duke Math. J. 755: 752: 748: 744: 740: 736: 732: 728: 724: 720: 716: 712: 708: 707: 702: 698: 695: 691: 687: 683: 679: 675: 671: 667: 663: 659: 655: 652:(in French), 651: 650: 645: 641: 637: 633: 631:0-387-95490-2 627: 623: 618: 614: 612:0-521-59820-6 608: 604: 603: 597: 596: 590: 588: 569: 553: 534: 530: 524: 518: 511: 510: 509: 508: 504: 500: 490: 488: 483: 478: 473: 468: 463: 458: 453: 451: 446: 444: 440: 421: 415: 412: 409: 406: 386: 382: 371: 363: 362: 361: 356:Ogg's formula 353: 351: 347: 343: 339: 335: 331: 327: 323: 319: 315: 296: 290: 287: 284: 273: 265: 261: 250: 245: 242: 238: 234: 230: 226: 223: 216: 215: 214: 212: 208: 204: 200: 196: 191: 186: 184: 180: 176: 172: 167: 162: 158: 154: 150: 146: 142: 138: 134: 131: 127: 117: 115: 111: 107: 105: 101: 96: 94: 84: 82: 78: 73: 71: 67: 66:bad reduction 63: 59: 55: 51: 47: 43: 39: 35: 31: 27: 23: 19: 986: 945: 941: 908: 902: 876: 850: 799: 793: 762: 758: 710: 704: 653: 647: 640:NĂ©ron, AndrĂ© 621: 601: 586: 584: 506: 502: 498: 496: 486: 481: 476: 471: 466: 461: 454: 450:Saito (1988) 447: 438: 436: 359: 349: 345: 341: 337: 333: 325: 321: 320:for a prime 317: 313: 311: 210: 202: 194: 189: 187: 182: 178: 174: 170: 165: 160: 152: 148: 144: 136: 132: 125: 123: 108: 97: 90: 77:discriminant 74: 50:ramification 46:prime ideals 30:global field 17: 15: 948:: 149–156, 713:(1): 1–21, 457:j-invariant 173:-unit then 130:local field 100:Weil (1967) 942:Math. Ann. 933:0296.14018 873:Tate, John 840:0172.46101 790:Tate, John 751:0147.39803 701:Ogg, A. P. 694:0132.41403 593:References 120:Definition 93:Ogg (1967) 970:120553723 925:120008651 895:John Tate 816:0003-486X 727:0002-9327 686:120802890 670:1618-1913 656:: 5–128, 535:∏ 413:− 401:Δ 387:ν 251:⁡ 224:δ 58:group law 997:Category 897:(1974). 875:(1992). 849:(1994). 642:(1964), 348:acts on 104:L-series 962:0207658 832:0236190 824:1970722 779:0952229 743:0207694 735:2373092 678:0179172 489:) ≄ 0. 328:is the 205:by the 87:History 60:of the 52:in the 968:  960:  931:  923:  883:  857:  838:  830:  822:  814:  777:  749:  741:  733:  725:  692:  684:  676:  668:  628:  609:  567:  437:where 419:  332:, and 966:S2CID 921:S2CID 820:JSTOR 731:JSTOR 682:S2CID 312:Here 40:of a 34:ideal 26:local 881:ISBN 855:ISBN 812:ISSN 723:ISSN 666:ISSN 626:ISBN 607:ISBN 497:Let 177:has 151:for 135:and 124:Let 950:doi 946:168 929:Zbl 913:doi 836:Zbl 804:doi 767:doi 747:Zbl 715:doi 690:Zbl 658:doi 256:Hom 231:dim 209:of 181:at 143:of 28:or 999:: 964:, 958:MR 956:, 944:, 927:. 919:. 909:23 907:. 901:. 871:; 834:, 828:MR 826:, 818:, 810:, 800:88 788:; 775:MR 773:, 763:57 761:, 745:, 739:MR 737:, 729:, 721:, 711:89 709:, 688:, 680:, 674:MR 672:, 664:, 654:21 646:, 352:) 324:, 116:. 83:. 72:. 987:Q 952:: 935:. 915:: 889:. 863:. 806:: 769:: 717:: 660:: 634:. 615:. 587:E 570:. 559:p 554:f 548:p 540:p 531:= 528:) 525:E 522:( 519:f 507:K 503:K 499:E 487:j 485:( 482:p 477:j 475:( 472:p 467:j 465:( 462:p 459:Îœ 439:n 422:, 416:n 410:1 407:+ 404:) 398:( 392:p 383:= 377:p 372:f 350:M 346:G 342:M 338:K 334:G 326:P 322:l 318:l 314:M 297:. 294:) 291:M 288:, 285:P 282:( 277:] 274:G 271:[ 266:l 262:Z 246:Z 243:l 239:/ 235:Z 227:= 211:E 203:K 195:p 190:f 183:p 175:E 171:p 166:p 161:p 153:E 145:K 137:p 133:K 126:E

Index

rational numbers
local
global field
ideal
Artin conductor
Galois representation
prime ideals
ramification
field extensions
group law
elliptic curve
bad reduction
NĂ©ron–Ogg–Shafarevich criterion
discriminant
Tate's algorithm
Ogg (1967)
Weil (1967)
L-series
Serre & Tate (1968)
conductors of abelian varieties
local field
ring of integers
Weierstrass equation
wild ramification
division points
Swan representation
NĂ©ron minimal model
Saito (1988)
j-invariant
Algorithms for Modular Elliptic Curves

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