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Twisted cubic

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33: 176: 887:, but not a scheme-theoretic or ideal-theoretic complete intersection; meaning to say that the ideal of the variety cannot be generated by only 2 polynomials; a minimum of 3 are needed. (An attempt to use only two polynomials make the resulting ideal not 237: 460: 885: 522: 938: 690: 640: 383: 739: 1129: 62: 974: 813: 577: 275: 1552: 1281: 1644: 1241: 1122: 1710: 1332: 1231: 1700: 1098: 84: 1410: 1115: 192: 1557: 1468: 113: 1478: 1405: 1155: 1375: 1271: 532: 1634: 1598: 45: 1297: 1210: 55: 49: 41: 1608: 1246: 401: 1735: 1654: 1041:
has the property that the tangent and secant lines are pairwise disjoint, except at points of the variety itself.
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and the lines are pairwise disjoint, except at points of the curve itself. In fact, the union of the
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vanish identically when using the explicit parameterization above; that is, substitute
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with no four coplanar, there is a unique twisted cubic passing through them.
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is generated by these three homogeneous polynomials of degree 2.
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with the property that every length four subscheme spans
232:{\displaystyle \nu :\mathbf {P} ^{1}\to \mathbf {P} ^{3}} 946: 897: 821: 785: 699: 649: 599: 541: 478: 404: 286: 251: 195: 1691: 1653: 1622: 1586: 1535: 1528: 1502: 1434: 1351: 1315: 1290: 1224: 1193: 1184: 1146: 968: 932: 879: 807: 733: 684: 634: 571: 516: 454: 377: 269: 231: 779:It is the set-theoretic complete intersection of 1059:The projection from a point on a secant line of 775:The twisted cubic has the following properties: 54:but its sources remain unclear because it lacks 1048:onto a plane from a point on a tangent line of 1123: 455:{\displaystyle \nu :x\mapsto (x,x^{2},x^{3})} 139:, the twisted cubic is a simple example of a 8: 392:of projective space, the map is simply the 1532: 1190: 1130: 1116: 1108: 1033:is three-dimensional. Further, any smooth 151:. It is the three-dimensional case of the 960: 945: 924: 914: 896: 841: 820: 799: 784: 704: 698: 676: 654: 648: 626: 604: 598: 540: 505: 492: 477: 443: 430: 403: 363: 350: 331: 318: 285: 250: 223: 218: 208: 203: 194: 85:Learn how and when to remove this message 531:, defined as the intersection of three 465:That is, it is the closure by a single 182:The twisted cubic is most easily given 1553:Clifford's theorem on special divisors 587:defined by the vanishing of the three 7: 880:{\displaystyle Z(YW-Z^{2})-W(XW-YZ)} 744:It may be checked that these three 123:. It is a fundamental example of a 1711:Vector bundles on algebraic curves 1645:Weber's theorem (Algebraic curves) 1242:Hasse's theorem on elliptic curves 1232:Counting points on elliptic curves 1091:Algebraic Geometry, A First Course 583:, the twisted cubic is the closed 127:. It is essentially unique, up to 25: 219: 204: 31: 1333:Hurwitz's automorphisms theorem 1070:The projection from a point on 1029:lines of any non-planar smooth 517:{\displaystyle (x,x^{2},x^{3})} 1558:Gonality of an algebraic curve 1469:Differential of the first kind 933:{\displaystyle (YW-Z^{2})^{2}} 921: 898: 874: 856: 847: 825: 685:{\displaystyle F_{1}=YW-Z^{2}} 635:{\displaystyle F_{0}=XZ-Y^{2}} 566: 542: 511: 479: 449: 417: 414: 378:{\displaystyle \nu :\mapsto .} 369: 311: 308: 305: 293: 264: 252: 214: 135:twisted cubic, therefore). In 1: 1701:Birkhoff–Grothendieck theorem 1411:Nagata's conjecture on curves 1282:Schoof–Elkies–Atkin algorithm 1156:Five points determine a conic 1093:, New York: Springer-Verlag, 535:. In homogeneous coordinates 1272:Supersingular elliptic curve 734:{\displaystyle F_{2}=XW-YZ.} 1479:Riemann's existence theorem 1406:Hilbert's sixteenth problem 1298:Elliptic curve cryptography 1211:Fundamental pair of periods 1752: 1609:Moduli of algebraic curves 129:projective transformation 1376:Cayley–Bacharach theorem 1303:Elliptic curve primality 969:{\displaystyle YW-Z^{2}} 808:{\displaystyle XZ-Y^{2}} 186:as the image of the map 143:that is not linear or a 40:This article includes a 1635:Riemann–Hurwitz formula 1599:Gromov–Witten invariant 1459:Compact Riemann surface 1247:Mazur's torsion theorem 589:homogeneous polynomials 527:The twisted cubic is a 163:of degree three on the 69:more precise citations. 1252:Modular elliptic curve 970: 934: 881: 809: 735: 686: 636: 573: 518: 456: 379: 271: 244:homogeneous coordinate 233: 179: 1166:Rational normal curve 1013:) of a twisted cubic 971: 935: 882: 810: 763:of the twisted cubic 736: 687: 637: 574: 519: 457: 380: 272: 242:which assigns to the 234: 178: 153:rational normal curve 149:complete intersection 1706:Stable vector bundle 1578:Weil reciprocity law 1568:Riemann–Roch theorem 1548:Brill–Noether theory 1484:Riemann–Roch theorem 1401:Genus–degree formula 1262:Mordell–Weil theorem 1237:Division polynomials 1089:Harris, Joe (1992), 990:Given six points in 944: 895: 819: 783: 697: 647: 597: 539: 476: 402: 284: 249: 193: 1529:Structure of curves 1421:Quartic plane curve 1343:Hyperelliptic curve 1323:De Franchis theorem 1267:Nagell–Lutz theorem 979:Any four points on 759:More strongly, the 1536:Divisors on curves 1328:Faltings's theorem 1277:Schoof's algorithm 1257:Modularity theorem 1044:The projection of 966: 930: 877: 805: 731: 682: 632: 569: 529:projective variety 514: 452: 375: 267: 229: 180: 141:projective variety 137:algebraic geometry 118:projective 3-space 42:list of references 1723: 1722: 1719: 1718: 1630:Hasse–Witt matrix 1573:Weierstrass point 1520:Smooth completion 1489:TeichmĂĽller space 1391:Cubic plane curve 1311: 1310: 1225:Arithmetic theory 1206:Elliptic integral 1201:Elliptic function 1035:algebraic variety 761:homogeneous ideal 467:point at infinity 95: 94: 87: 16:(Redirected from 1743: 1736:Algebraic curves 1563:Jacobian variety 1533: 1436:Riemann surfaces 1426:Real plane curve 1386:Cramer's paradox 1366:BĂ©zout's theorem 1191: 1140:algebraic curves 1132: 1125: 1118: 1109: 1103: 975: 973: 972: 967: 965: 964: 939: 937: 936: 931: 929: 928: 919: 918: 886: 884: 883: 878: 846: 845: 814: 812: 811: 806: 804: 803: 740: 738: 737: 732: 709: 708: 691: 689: 688: 683: 681: 680: 659: 658: 641: 639: 638: 633: 631: 630: 609: 608: 578: 576: 575: 572:{\displaystyle } 570: 523: 521: 520: 515: 510: 509: 497: 496: 461: 459: 458: 453: 448: 447: 435: 434: 390:coordinate patch 384: 382: 381: 376: 368: 367: 355: 354: 336: 335: 323: 322: 276: 274: 273: 270:{\displaystyle } 268: 238: 236: 235: 230: 228: 227: 222: 213: 212: 207: 147:, in fact not a 90: 83: 79: 76: 70: 65:this article by 56:inline citations 35: 34: 27: 21: 1751: 1750: 1746: 1745: 1744: 1742: 1741: 1740: 1726: 1725: 1724: 1715: 1687: 1678:Delta invariant 1649: 1618: 1582: 1543:Abel–Jacobi map 1524: 1498: 1494:Torelli theorem 1464:Dessin d'enfant 1444:Belyi's theorem 1430: 1416:PlĂĽcker formula 1347: 1338:Hurwitz surface 1307: 1286: 1220: 1194:Analytic theory 1186:Elliptic curves 1180: 1161:Projective line 1148:Rational curves 1142: 1136: 1101: 1088: 1085: 1031:algebraic curve 956: 942: 941: 920: 910: 893: 892: 837: 817: 816: 795: 781: 780: 773: 746:quadratic forms 700: 695: 694: 672: 650: 645: 644: 622: 600: 595: 594: 537: 536: 501: 488: 474: 473: 439: 426: 400: 399: 359: 346: 327: 314: 282: 281: 247: 246: 217: 202: 191: 190: 173: 165:projective line 91: 80: 74: 71: 60: 46:related reading 36: 32: 23: 22: 15: 12: 11: 5: 1749: 1747: 1739: 1738: 1728: 1727: 1721: 1720: 1717: 1716: 1714: 1713: 1708: 1703: 1697: 1695: 1693:Vector bundles 1689: 1688: 1686: 1685: 1680: 1675: 1670: 1665: 1659: 1657: 1651: 1650: 1648: 1647: 1642: 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1638: 1636: 1633: 1631: 1628: 1627: 1625: 1621: 1615: 1612: 1610: 1607: 1605: 1602: 1600: 1597: 1595: 1592: 1591: 1589: 1585: 1579: 1576: 1574: 1571: 1569: 1566: 1564: 1561: 1559: 1556: 1554: 1551: 1549: 1546: 1544: 1541: 1540: 1538: 1534: 1531: 1527: 1521: 1518: 1516: 1513: 1511: 1508: 1507: 1505: 1503:Constructions 1501: 1495: 1492: 1490: 1487: 1485: 1482: 1480: 1477: 1475: 1474:Klein quartic 1472: 1470: 1467: 1465: 1462: 1460: 1457: 1455: 1454:Bolza surface 1452: 1450: 1449:Bring's curve 1447: 1445: 1442: 1441: 1439: 1437: 1433: 1427: 1424: 1422: 1419: 1417: 1414: 1412: 1409: 1407: 1404: 1402: 1399: 1397: 1394: 1392: 1389: 1387: 1384: 1382: 1381:Conic section 1379: 1377: 1374: 1372: 1369: 1367: 1364: 1362: 1361:AF+BG theorem 1359: 1358: 1356: 1354: 1350: 1344: 1341: 1339: 1336: 1334: 1331: 1329: 1326: 1324: 1321: 1320: 1318: 1314: 1304: 1301: 1299: 1296: 1295: 1293: 1289: 1283: 1280: 1278: 1275: 1273: 1270: 1268: 1265: 1263: 1260: 1258: 1255: 1253: 1250: 1248: 1245: 1243: 1240: 1238: 1235: 1233: 1230: 1229: 1227: 1223: 1217: 1214: 1212: 1209: 1207: 1204: 1202: 1199: 1198: 1196: 1192: 1189: 1187: 1183: 1177: 1176:Twisted cubic 1174: 1172: 1169: 1167: 1164: 1162: 1159: 1157: 1154: 1153: 1151: 1149: 1145: 1141: 1133: 1128: 1126: 1121: 1119: 1114: 1113: 1110: 1102: 1100:0-387-97716-3 1096: 1092: 1087: 1086: 1082: 1077: 1076:conic section 1073: 1069: 1066: 1062: 1058: 1055: 1051: 1047: 1043: 1040: 1036: 1032: 1028: 1024: 1020: 1016: 1012: 1008: 1004: 1000: 996: 993: 989: 986: 982: 978: 961: 957: 953: 950: 947: 925: 915: 911: 907: 904: 901: 890: 871: 868: 865: 862: 859: 853: 850: 842: 838: 834: 831: 828: 822: 800: 796: 792: 789: 786: 778: 777: 776: 770: 768: 766: 762: 757: 756:, and so on. 755: 751: 747: 728: 725: 722: 719: 716: 713: 710: 705: 701: 693: 677: 673: 669: 666: 663: 660: 655: 651: 643: 627: 623: 619: 616: 613: 610: 605: 601: 593: 592: 591: 590: 586: 582: 563: 560: 557: 554: 551: 548: 545: 534: 530: 525: 506: 502: 498: 493: 489: 485: 482: 472: 468: 444: 440: 436: 431: 427: 423: 420: 411: 408: 405: 398: 397: 396: 395: 391: 372: 364: 360: 356: 351: 347: 343: 340: 337: 332: 328: 324: 319: 315: 302: 299: 296: 290: 287: 280: 279: 278: 261: 258: 255: 245: 224: 209: 199: 196: 189: 188: 187: 185: 177: 170: 168: 166: 162: 158: 155:, and is the 154: 150: 146: 142: 138: 134: 130: 126: 122: 119: 115: 111: 108: 105:is a smooth, 104: 103:twisted cubic 100: 89: 86: 78: 75:February 2022 68: 64: 58: 57: 51: 47: 43: 38: 29: 28: 19: 1640:Prym variety 1614:Stable curve 1604:Hodge bundle 1594:ELSV formula 1396:Fermat curve 1353:Plane curves 1316:Higher genus 1291:Applications 1216:Modular form 1175: 1090: 1071: 1060: 1049: 1045: 1038: 1018: 1014: 1007:secant lines 991: 984: 980: 774: 764: 758: 753: 749: 743: 580: 526: 471:affine curve 464: 394:moment curve 387: 241: 181: 161:Veronese map 145:hypersurface 132: 120: 109: 102: 96: 81: 72: 61:Please help 53: 1515:Polar curve 99:mathematics 67:introducing 1510:Dual curve 1138:Topics in 1083:References 771:Properties 277:the value 171:Definition 125:skew curve 1623:Morphisms 1371:Bitangent 1074:yields a 1063:yields a 1052:yields a 954:− 908:− 891:, since 866:− 851:− 835:− 793:− 720:− 670:− 620:− 585:subscheme 415:↦ 406:ν 309:↦ 288:ν 215:→ 197:ν 116:three in 1730:Category 1017:fill up 976:is not). 533:quadrics 1683:Tacnode 1668:Crunode 1023:tangent 1003:tangent 1001:of the 889:radical 469:of the 388:In one 63:improve 1663:Acnode 1587:Moduli 1097:  1067:cubic. 1027:secant 114:degree 1065:nodal 1009:(the 999:union 983:span 159:of a 157:image 48:, or 1673:Cusp 1095:ISBN 1025:and 1005:and 997:The 815:and 752:for 101:, a 579:on 133:the 112:of 97:In 1732:: 524:. 167:. 52:, 44:, 1131:e 1124:t 1117:v 1104:. 1078:. 1072:C 1061:C 1056:. 1050:C 1046:C 1039:P 1019:P 1015:C 992:P 987:. 985:P 981:C 962:2 958:Z 951:W 948:Y 926:2 922:) 916:2 912:Z 905:W 902:Y 899:( 875:) 872:Z 869:Y 863:W 860:X 857:( 854:W 848:) 843:2 839:Z 832:W 829:Y 826:( 823:Z 801:2 797:Y 790:Z 787:X 765:C 754:X 750:x 729:. 726:Z 723:Y 717:W 714:X 711:= 706:2 702:F 678:2 674:Z 667:W 664:Y 661:= 656:1 652:F 628:2 624:Y 617:Z 614:X 611:= 606:0 602:F 581:P 567:] 564:W 561:: 558:Z 555:: 552:Y 549:: 546:X 543:[ 512:) 507:3 503:x 499:, 494:2 490:x 486:, 483:x 480:( 450:) 445:3 441:x 437:, 432:2 428:x 424:, 421:x 418:( 412:x 409:: 373:. 370:] 365:3 361:T 357:: 352:2 348:T 344:S 341:: 338:T 333:2 329:S 325:: 320:3 316:S 312:[ 306:] 303:T 300:: 297:S 294:[ 291:: 265:] 262:T 259:: 256:S 253:[ 225:3 220:P 210:1 205:P 200:: 131:( 121:P 110:C 88:) 82:( 77:) 73:( 59:. 20:)

Index

Twisted cubics
list of references
related reading
external links
inline citations
improve
introducing
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mathematics
rational curve
degree
projective 3-space
skew curve
projective transformation
algebraic geometry
projective variety
hypersurface
complete intersection
rational normal curve
image
Veronese map
projective line

parametrically
homogeneous coordinate
coordinate patch
moment curve
point at infinity
affine curve
projective variety

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