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Genus–degree formula

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are equal, but if the curve is singular, with only ordinary singularities, the geometric genus is smaller. More precisely, an ordinary
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Creative Commons Attribution-ShareAlike 3.0 Unported License
421: 419: 359: 320: 293: 221: 176: 153: 84: 54: 1245: 1207: 1176: 1140: 1089: 1082: 1056: 988: 905: 869: 844: 778: 747: 738: 700: 454: 402: 335: 299: 252: 191: 159: 136: 60: 390: 369: 596:. Geometry of algebraic curves. vol 1 Springer, 274:Adjunction formula § Applications to curves 268:The genus–degree formula can be proven from the 677: 445: 424: 8: 565:This article incorporates material from the 614:, Principles of algebraic geometry, Wiley, 137:{\displaystyle g={\frac {1}{2}}(d-1)(d-2).} 1086: 744: 684: 670: 662: 444: 423: 420: 418: 399: 389: 368: 366: 358: 327: 323: 322: 319: 292: 222: 220: 183: 179: 178: 175: 152: 91: 83: 53: 474: 27:Theorem in classical algebraic geometry 1107:Clifford's theorem on special divisors 403:{\displaystyle g={\binom {d-1}{n}},\,} 7: 253:{\displaystyle {\frac {1}{2}}r(r-1)} 199:. If the curve is non-singular the 1265:Vector bundles on algebraic curves 1199:Weber's theorem (Algebraic curves) 796:Hasse's theorem on elliptic curves 786:Counting points on elliptic curves 491:Introduction to Algebraic Geometry 455:{\displaystyle {\tbinom {d-1}{n}}} 428: 373: 25: 336:{\displaystyle \mathbb {P} ^{n}} 192:{\displaystyle \mathbb {P} ^{2}} 887:Hurwitz's automorphisms theorem 573:", which is licensed under the 1112:Gonality of an algebraic curve 1023:Differential of the first kind 247: 235: 147:Here "plane curve" means that 128: 116: 113: 101: 1: 1255:Birkhoff–Grothendieck theorem 965:Nagata's conjecture on curves 836:Schoof–Elkies–Atkin algorithm 710:Five points determine a conic 826:Supersingular elliptic curve 644:Kulikov, Viktor S. (2001) , 1033:Riemann's existence theorem 960:Hilbert's sixteenth problem 852:Elliptic curve cryptography 765:Fundamental pair of periods 651:Encyclopedia of Mathematics 1306: 1163:Moduli of algebraic curves 540:, chapter V, example 1.5.1 167:is a closed curve in the 930:Cayley–Bacharach theorem 857:Elliptic curve primality 1189:Riemann–Hurwitz formula 1153:Gromov–Witten invariant 1013:Compact Riemann surface 801:Mazur's torsion theorem 622:, chapter 2, section 1. 495:Oxford University Press 215:decreases the genus by 806:Modular elliptic curve 483:Semple, John Greenlees 456: 404: 337: 301: 254: 193: 161: 138: 62: 720:Rational normal curve 588:, Maurizio Cornalba, 457: 405: 350:the formula becomes: 338: 302: 255: 194: 162: 139: 63: 1260:Stable vector bundle 1132:Weil reciprocity law 1122:Riemann–Roch theorem 1102:Brill–Noether theory 1038:Riemann–Roch theorem 955:Genus–degree formula 816:Mordell–Weil theorem 791:Division polynomials 571:Genus degree formula 464:binomial coefficient 417: 357: 318: 291: 219: 174: 151: 82: 52: 36:genus–degree formula 1083:Structure of curves 975:Quartic plane curve 897:Hyperelliptic curve 877:De Franchis theorem 821:Nagell–Lutz theorem 532:, Springer GTM 52, 284:For a non-singular 272:; for details, see 38:relates the degree 1090:Divisors on curves 882:Faltings's theorem 831:Schoof's algorithm 811:Modularity theorem 646:"Genus of a curve" 630:Algebraic geometry 577:but not under the 526:Algebraic geometry 497:. pp. 53–54. 452: 450: 400: 333: 297: 270:adjunction formula 250: 189: 157: 134: 58: 32:algebraic geometry 1277: 1276: 1273: 1272: 1184:Hasse–Witt matrix 1127:Weierstrass point 1074:Smooth completion 1043:Teichmüller space 945:Cubic plane curve 865: 864: 779:Arithmetic theory 760:Elliptic integral 755:Elliptic function 608:Phillip Griffiths 590:Phillip Griffiths 493:(1985 ed.). 443: 388: 300:{\displaystyle H} 230: 160:{\displaystyle C} 99: 75:via the formula: 61:{\displaystyle C} 16:(Redirected from 1297: 1290:Algebraic curves 1117:Jacobian variety 1087: 990:Riemann surfaces 980:Real plane curve 940:Cramer's paradox 920:Bézout's theorem 745: 694:algebraic curves 686: 679: 672: 663: 658: 626:Robin Hartshorne 586:Enrico Arbarello 541: 530:Robin Hartshorne 523: 517: 516: 479: 461: 459: 458: 453: 451: 449: 448: 439: 427: 409: 407: 406: 401: 395: 394: 393: 384: 372: 345:arithmetic genus 342: 340: 339: 334: 332: 331: 326: 313:projective space 306: 304: 303: 298: 259: 257: 256: 251: 231: 223: 211:of multiplicity 205:arithmetic genus 198: 196: 195: 190: 188: 187: 182: 169:projective plane 166: 164: 163: 158: 143: 141: 140: 135: 100: 92: 70:arithmetic genus 67: 65: 64: 59: 21: 1305: 1304: 1300: 1299: 1298: 1296: 1295: 1294: 1280: 1279: 1278: 1269: 1241: 1232:Delta invariant 1203: 1172: 1136: 1097:Abel–Jacobi map 1078: 1052: 1048:Torelli theorem 1018:Dessin d'enfant 998:Belyi's theorem 984: 970:Plücker formula 901: 892:Hurwitz surface 861: 840: 774: 748:Analytic theory 740:Elliptic curves 734: 715:Projective line 702:Rational curves 696: 690: 643: 561: 553:Thom conjecture 549: 544: 524: 520: 505: 481: 480: 476: 472: 429: 422: 415: 414: 374: 367: 355: 354: 321: 316: 315: 289: 288: 282: 266: 217: 216: 201:geometric genus 177: 172: 171: 149: 148: 80: 79: 50: 49: 28: 23: 22: 15: 12: 11: 5: 1303: 1301: 1293: 1292: 1282: 1281: 1275: 1274: 1271: 1270: 1268: 1267: 1262: 1257: 1251: 1249: 1247:Vector bundles 1243: 1242: 1240: 1239: 1234: 1229: 1224: 1219: 1213: 1211: 1205: 1204: 1202: 1201: 1196: 1191: 1186: 1180: 1178: 1174: 1173: 1171: 1170: 1165: 1160: 1155: 1150: 1144: 1142: 1138: 1137: 1135: 1134: 1129: 1124: 1119: 1114: 1109: 1104: 1099: 1093: 1091: 1084: 1080: 1079: 1077: 1076: 1071: 1066: 1060: 1058: 1054: 1053: 1051: 1050: 1045: 1040: 1035: 1030: 1025: 1020: 1015: 1010: 1005: 1000: 994: 992: 986: 985: 983: 982: 977: 972: 967: 962: 957: 952: 947: 942: 937: 932: 927: 922: 917: 911: 909: 903: 902: 900: 899: 894: 889: 884: 879: 873: 871: 867: 866: 863: 862: 860: 859: 854: 848: 846: 842: 841: 839: 838: 833: 828: 823: 818: 813: 808: 803: 798: 793: 788: 782: 780: 776: 775: 773: 772: 767: 762: 757: 751: 749: 742: 736: 735: 733: 732: 727: 725:Riemann sphere 722: 717: 712: 706: 704: 698: 697: 691: 689: 688: 681: 674: 666: 660: 659: 641: 623: 605: 583: 560: 557: 556: 555: 548: 545: 543: 542: 518: 503: 473: 471: 468: 447: 442: 438: 435: 432: 426: 411: 410: 398: 392: 387: 383: 380: 377: 371: 365: 362: 330: 325: 296: 281: 280:Generalization 278: 265: 262: 249: 246: 243: 240: 237: 234: 229: 226: 186: 181: 156: 145: 144: 133: 130: 127: 124: 121: 118: 115: 112: 109: 106: 103: 98: 95: 90: 87: 57: 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 1302: 1291: 1288: 1287: 1285: 1266: 1263: 1261: 1258: 1256: 1253: 1252: 1250: 1248: 1244: 1238: 1235: 1233: 1230: 1228: 1225: 1223: 1220: 1218: 1215: 1214: 1212: 1210: 1209:Singularities 1206: 1200: 1197: 1195: 1192: 1190: 1187: 1185: 1182: 1181: 1179: 1175: 1169: 1166: 1164: 1161: 1159: 1156: 1154: 1151: 1149: 1146: 1145: 1143: 1139: 1133: 1130: 1128: 1125: 1123: 1120: 1118: 1115: 1113: 1110: 1108: 1105: 1103: 1100: 1098: 1095: 1094: 1092: 1088: 1085: 1081: 1075: 1072: 1070: 1067: 1065: 1062: 1061: 1059: 1057:Constructions 1055: 1049: 1046: 1044: 1041: 1039: 1036: 1034: 1031: 1029: 1028:Klein quartic 1026: 1024: 1021: 1019: 1016: 1014: 1011: 1009: 1008:Bolza surface 1006: 1004: 1003:Bring's curve 1001: 999: 996: 995: 993: 991: 987: 981: 978: 976: 973: 971: 968: 966: 963: 961: 958: 956: 953: 951: 948: 946: 943: 941: 938: 936: 935:Conic section 933: 931: 928: 926: 923: 921: 918: 916: 915:AF+BG theorem 913: 912: 910: 908: 904: 898: 895: 893: 890: 888: 885: 883: 880: 878: 875: 874: 872: 868: 858: 855: 853: 850: 849: 847: 843: 837: 834: 832: 829: 827: 824: 822: 819: 817: 814: 812: 809: 807: 804: 802: 799: 797: 794: 792: 789: 787: 784: 783: 781: 777: 771: 768: 766: 763: 761: 758: 756: 753: 752: 750: 746: 743: 741: 737: 731: 730:Twisted cubic 728: 726: 723: 721: 718: 716: 713: 711: 708: 707: 705: 703: 699: 695: 687: 682: 680: 675: 673: 668: 667: 664: 657: 653: 652: 647: 642: 639: 638:0-387-90244-9 635: 631: 627: 624: 621: 620:0-471-05059-8 617: 613: 609: 606: 604:, appendix A. 603: 602:0-387-90997-4 599: 595: 591: 587: 584: 582: 580: 576: 572: 568: 563: 562: 558: 554: 551: 550: 546: 539: 538:0-387-90244-9 535: 531: 527: 522: 519: 514: 510: 506: 504:0-19-853363-2 500: 496: 492: 488: 487:Roth, Leonard 484: 478: 475: 469: 467: 465: 440: 436: 433: 430: 396: 385: 381: 378: 375: 363: 360: 353: 352: 351: 349: 346: 328: 314: 310: 294: 287: 279: 277: 275: 271: 263: 261: 244: 241: 238: 232: 227: 224: 214: 210: 206: 202: 184: 170: 154: 131: 125: 122: 119: 110: 107: 104: 96: 93: 88: 85: 78: 77: 76: 74: 71: 55: 48: 45: 41: 37: 33: 30:In classical 19: 18:Genus formula 1194:Prym variety 1168:Stable curve 1158:Hodge bundle 1148:ELSV formula 954: 950:Fermat curve 907:Plane curves 870:Higher genus 845:Applications 770:Modular form 649: 632:, Springer, 629: 564: 525: 521: 490: 477: 412: 347: 308: 286:hypersurface 283: 267: 212: 146: 72: 39: 35: 29: 1069:Polar curve 567:Citizendium 209:singularity 47:plane curve 44:irreducible 1064:Dual curve 692:Topics in 612:Joe Harris 594:Joe Harris 559:References 307:of degree 1177:Morphisms 925:Bitangent 656:EMS Press 569:article " 434:− 379:− 242:− 123:− 108:− 68:with its 1284:Category 628:(1977): 547:See also 203:and the 1237:Tacnode 1222:Crunode 513:0814690 462:is the 311:in the 1217:Acnode 1141:Moduli 636:  618:  600:  536:  511:  501:  413:where 42:of an 34:, the 470:Notes 264:Proof 1227:Cusp 634:ISBN 616:ISBN 610:and 598:ISBN 579:GFDL 534:ISBN 499:ISBN 343:of 1286:: 654:, 648:, 592:, 528:, 509:MR 507:. 489:. 485:; 466:. 276:. 260:. 685:e 678:t 671:v 640:. 581:. 515:. 446:) 441:n 437:1 431:d 425:( 397:, 391:) 386:n 382:1 376:d 370:( 364:= 361:g 348:g 329:n 324:P 309:d 295:H 248:) 245:1 239:r 236:( 233:r 228:2 225:1 213:r 185:2 180:P 155:C 132:. 129:) 126:2 120:d 117:( 114:) 111:1 105:d 102:( 97:2 94:1 89:= 86:g 73:g 56:C 40:d 20:)

Index

Genus formula
algebraic geometry
irreducible
plane curve
arithmetic genus
projective plane
geometric genus
arithmetic genus
singularity
adjunction formula
Adjunction formula § Applications to curves
hypersurface
projective space
arithmetic genus
binomial coefficient
Semple, John Greenlees
Roth, Leonard
Oxford University Press
ISBN
0-19-853363-2
MR
0814690
Robin Hartshorne
ISBN
0-387-90244-9
Thom conjecture
Citizendium
Genus degree formula
Creative Commons Attribution-ShareAlike 3.0 Unported License
GFDL

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