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Twisted cubic

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22: 165: 876:, 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 226: 449: 874: 511: 927: 679: 629: 372: 728: 963: 802: 566: 264: 1118: 51: 1541: 181: 1633: 1270: 1230: 1111: 1710: 1321: 1220: 1700: 1087: 73: 44: 1399: 1104: 390: 1030:
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
221:{\displaystyle \nu :\mathbf {P} ^{1}\to \mathbf {P} ^{3}} 935: 886: 810: 774: 688: 638: 588: 530: 467: 393: 275: 240: 184: 957: 921: 868: 796: 722: 673: 623: 560: 505: 443: 366: 258: 220: 768:It is the set-theoretic complete intersection of 1727: 1048:The projection from a point on a secant line of 764:The twisted cubic has the following properties: 43:but its sources remain unclear because it lacks 1037:onto a plane from a point on a tangent line of 1126: 1112: 444:{\displaystyle \nu :x\mapsto (x,x^{2},x^{3})} 128:, the twisted cubic is a simple example of a 381:of projective space, the map is simply the 1119: 1105: 1022:is three-dimensional. Further, any smooth 140:. It is the three-dimensional case of the 74:Learn how and when to remove this message 520:, defined as the intersection of three 454:That is, it is the closure by a single 171:The twisted cubic is most easily given 1728: 1542:Clifford's theorem on special divisors 1077: 576:defined by the vanishing of the three 1100: 869:{\displaystyle Z(YW-Z^{2})-W(XW-YZ)} 15: 733:It may be checked that these three 112:. It is a fundamental example of a 13: 1711:Vector bundles on algebraic curves 1634:Weber's theorem (Algebraic curves) 1231:Hasse's theorem on elliptic curves 1221:Counting points on elliptic curves 1080:Algebraic Geometry, A First Course 572:, the twisted cubic is the closed 163: 116:. It is essentially unique, up to 14: 1747: 208: 193: 20: 1322:Hurwitz's automorphisms theorem 1059:The projection from a point on 1018:lines of any non-planar smooth 506:{\displaystyle (x,x^{2},x^{3})} 1547:Gonality of an algebraic curve 1458:Differential of the first kind 922:{\displaystyle (YW-Z^{2})^{2}} 910: 887: 863: 845: 836: 814: 674:{\displaystyle F_{1}=YW-Z^{2}} 624:{\displaystyle F_{0}=XZ-Y^{2}} 555: 531: 500: 468: 438: 406: 403: 367:{\displaystyle \nu :\mapsto .} 358: 300: 297: 294: 282: 253: 241: 203: 124:twisted cubic, therefore). In 1: 1701:Birkhoff–Grothendieck theorem 1400:Nagata's conjecture on curves 1271:Schoof–Elkies–Atkin algorithm 1145:Five points determine a conic 1082:, New York: Springer-Verlag, 1071: 759: 524:. In homogeneous coordinates 159: 1261:Supersingular elliptic curve 723:{\displaystyle F_{2}=XW-YZ.} 7: 1468:Riemann's existence theorem 1395:Hilbert's sixteenth problem 1287:Elliptic curve cryptography 1200:Fundamental pair of periods 10: 1752: 1598:Moduli of algebraic curves 1691: 1642: 1611: 1575: 1524: 1517: 1491: 1423: 1340: 1304: 1279: 1213: 1182: 1173: 1135: 118:projective transformation 1365:Cayley–Bacharach theorem 1292:Elliptic curve primality 958:{\displaystyle YW-Z^{2}} 797:{\displaystyle XZ-Y^{2}} 175:as the image of the map 132:that is not linear or a 29:This article includes a 1624:Riemann–Hurwitz formula 1588:Gromov–Witten invariant 1448:Compact Riemann surface 1236:Mazur's torsion theorem 578:homogeneous polynomials 516:The twisted cubic is a 152:of degree three on the 58:more precise citations. 1241:Modular elliptic curve 959: 923: 870: 798: 724: 675: 625: 562: 507: 445: 368: 260: 233:homogeneous coordinate 222: 168: 1155:Rational normal curve 1002:) of a twisted cubic 960: 924: 871: 799: 752:of the twisted cubic 725: 676: 626: 563: 508: 446: 369: 261: 231:which assigns to the 223: 167: 142:rational normal curve 138:complete intersection 1706:Stable vector bundle 1567:Weil reciprocity law 1557:Riemann–Roch theorem 1537:Brill–Noether theory 1473:Riemann–Roch theorem 1390:Genus–degree formula 1251:Mordell–Weil theorem 1226:Division polynomials 1078:Harris, Joe (1992), 979:Given six points in 933: 884: 808: 772: 686: 636: 586: 528: 465: 391: 273: 238: 182: 1518:Structure of curves 1410:Quartic plane curve 1332:Hyperelliptic curve 1312:De Franchis theorem 1256:Nagell–Lutz theorem 968:Any four points on 748:More strongly, the 1525:Divisors on curves 1317:Faltings's theorem 1266:Schoof's algorithm 1246:Modularity theorem 1033:The projection of 955: 919: 866: 794: 720: 671: 621: 558: 518:projective variety 503: 441: 364: 256: 218: 169: 130:projective variety 126:algebraic geometry 107:projective 3-space 31:list of references 1723: 1722: 1719: 1718: 1619:Hasse–Witt matrix 1562:Weierstrass point 1509:Smooth completion 1478:TeichmĂĽller space 1380:Cubic plane curve 1300: 1299: 1214:Arithmetic theory 1195:Elliptic integral 1190:Elliptic function 1024:algebraic variety 750:homogeneous ideal 456:point at infinity 84: 83: 76: 1743: 1736:Algebraic curves 1552:Jacobian variety 1522: 1521: 1425:Riemann surfaces 1415:Real plane curve 1375:Cramer's paradox 1355:BĂ©zout's theorem 1180: 1179: 1129:algebraic curves 1121: 1114: 1107: 1098: 1097: 1092: 964: 962: 961: 956: 954: 953: 928: 926: 925: 920: 918: 917: 908: 907: 875: 873: 872: 867: 835: 834: 803: 801: 800: 795: 793: 792: 729: 727: 726: 721: 698: 697: 680: 678: 677: 672: 670: 669: 648: 647: 630: 628: 627: 622: 620: 619: 598: 597: 567: 565: 564: 561:{\displaystyle } 559: 512: 510: 509: 504: 499: 498: 486: 485: 450: 448: 447: 442: 437: 436: 424: 423: 379:coordinate patch 373: 371: 370: 365: 357: 356: 344: 343: 325: 324: 312: 311: 265: 263: 262: 259:{\displaystyle } 257: 227: 225: 224: 219: 217: 216: 211: 202: 201: 196: 136:, in fact not a 79: 72: 68: 65: 59: 54:this article by 45:inline citations 24: 23: 16: 1751: 1750: 1746: 1745: 1744: 1742: 1741: 1740: 1726: 1725: 1724: 1715: 1687: 1678:Delta invariant 1656: 1638: 1607: 1571: 1532:Abel–Jacobi map 1513: 1487: 1483:Torelli theorem 1453:Dessin d'enfant 1433:Belyi's theorem 1419: 1405:PlĂĽcker formula 1336: 1327:Hurwitz surface 1296: 1275: 1209: 1183:Analytic theory 1175:Elliptic curves 1169: 1150:Projective line 1137:Rational curves 1131: 1125: 1090: 1074: 1020:algebraic curve 949: 945: 934: 931: 930: 913: 909: 903: 899: 885: 882: 881: 830: 826: 809: 806: 805: 788: 784: 773: 770: 769: 762: 735:quadratic forms 693: 689: 687: 684: 683: 665: 661: 643: 639: 637: 634: 633: 615: 611: 593: 589: 587: 584: 583: 529: 526: 525: 494: 490: 481: 477: 466: 463: 462: 432: 428: 419: 415: 392: 389: 388: 352: 348: 339: 335: 320: 316: 307: 303: 274: 271: 270: 239: 236: 235: 212: 207: 206: 197: 192: 191: 183: 180: 179: 162: 154:projective line 80: 69: 63: 60: 49: 35:related reading 25: 21: 12: 11: 5: 1749: 1739: 1738: 1721: 1720: 1717: 1716: 1714: 1713: 1708: 1703: 1697: 1695: 1693:Vector bundles 1689: 1688: 1686: 1685: 1680: 1675: 1670: 1665: 1660: 1654: 1648: 1646: 1640: 1639: 1637: 1636: 1631: 1626: 1621: 1615: 1613: 1609: 1608: 1606: 1605: 1600: 1595: 1590: 1585: 1579: 1577: 1573: 1572: 1570: 1569: 1564: 1559: 1554: 1549: 1544: 1539: 1534: 1528: 1526: 1519: 1515: 1514: 1512: 1511: 1506: 1501: 1495: 1493: 1489: 1488: 1486: 1485: 1480: 1475: 1470: 1465: 1460: 1455: 1450: 1445: 1440: 1435: 1429: 1427: 1421: 1420: 1418: 1417: 1412: 1407: 1402: 1397: 1392: 1387: 1382: 1377: 1372: 1367: 1362: 1357: 1352: 1346: 1344: 1338: 1337: 1335: 1334: 1329: 1324: 1319: 1314: 1308: 1306: 1302: 1301: 1298: 1297: 1295: 1294: 1289: 1283: 1281: 1277: 1276: 1274: 1273: 1268: 1263: 1258: 1253: 1248: 1243: 1238: 1233: 1228: 1223: 1217: 1215: 1211: 1210: 1208: 1207: 1202: 1197: 1192: 1186: 1184: 1177: 1171: 1170: 1168: 1167: 1162: 1160:Riemann sphere 1157: 1152: 1147: 1141: 1139: 1133: 1132: 1124: 1123: 1116: 1109: 1101: 1095: 1094: 1088: 1073: 1070: 1069: 1068: 1057: 1046: 1043:cuspidal cubic 1031: 1000:secant variety 984: 977: 966: 952: 948: 944: 941: 938: 929:is in it, but 916: 912: 906: 902: 898: 895: 892: 889: 865: 862: 859: 856: 853: 850: 847: 844: 841: 838: 833: 829: 825: 822: 819: 816: 813: 791: 787: 783: 780: 777: 761: 758: 731: 730: 719: 716: 713: 710: 707: 704: 701: 696: 692: 681: 668: 664: 660: 657: 654: 651: 646: 642: 631: 618: 614: 610: 607: 604: 601: 596: 592: 557: 554: 551: 548: 545: 542: 539: 536: 533: 502: 497: 493: 489: 484: 480: 476: 473: 470: 452: 451: 440: 435: 431: 427: 422: 418: 414: 411: 408: 405: 402: 399: 396: 375: 374: 363: 360: 355: 351: 347: 342: 338: 334: 331: 328: 323: 319: 315: 310: 306: 302: 299: 296: 293: 290: 287: 284: 281: 278: 255: 252: 249: 246: 243: 229: 228: 215: 210: 205: 200: 195: 190: 187: 173:parametrically 161: 158: 96:rational curve 82: 81: 39:external links 28: 26: 19: 9: 6: 4: 3: 2: 1748: 1737: 1734: 1733: 1731: 1712: 1709: 1707: 1704: 1702: 1699: 1698: 1696: 1694: 1690: 1684: 1681: 1679: 1676: 1674: 1671: 1669: 1666: 1664: 1661: 1659: 1657: 1650: 1649: 1647: 1645: 1644:Singularities 1641: 1635: 1632: 1630: 1627: 1625: 1622: 1620: 1617: 1616: 1614: 1610: 1604: 1601: 1599: 1596: 1594: 1591: 1589: 1586: 1584: 1581: 1580: 1578: 1574: 1568: 1565: 1563: 1560: 1558: 1555: 1553: 1550: 1548: 1545: 1543: 1540: 1538: 1535: 1533: 1530: 1529: 1527: 1523: 1520: 1516: 1510: 1507: 1505: 1502: 1500: 1497: 1496: 1494: 1492:Constructions 1490: 1484: 1481: 1479: 1476: 1474: 1471: 1469: 1466: 1464: 1463:Klein quartic 1461: 1459: 1456: 1454: 1451: 1449: 1446: 1444: 1443:Bolza surface 1441: 1439: 1438:Bring's curve 1436: 1434: 1431: 1430: 1428: 1426: 1422: 1416: 1413: 1411: 1408: 1406: 1403: 1401: 1398: 1396: 1393: 1391: 1388: 1386: 1383: 1381: 1378: 1376: 1373: 1371: 1370:Conic section 1368: 1366: 1363: 1361: 1358: 1356: 1353: 1351: 1350:AF+BG theorem 1348: 1347: 1345: 1343: 1339: 1333: 1330: 1328: 1325: 1323: 1320: 1318: 1315: 1313: 1310: 1309: 1307: 1303: 1293: 1290: 1288: 1285: 1284: 1282: 1278: 1272: 1269: 1267: 1264: 1262: 1259: 1257: 1254: 1252: 1249: 1247: 1244: 1242: 1239: 1237: 1234: 1232: 1229: 1227: 1224: 1222: 1219: 1218: 1216: 1212: 1206: 1203: 1201: 1198: 1196: 1193: 1191: 1188: 1187: 1185: 1181: 1178: 1176: 1172: 1166: 1165:Twisted cubic 1163: 1161: 1158: 1156: 1153: 1151: 1148: 1146: 1143: 1142: 1140: 1138: 1134: 1130: 1122: 1117: 1115: 1110: 1108: 1103: 1102: 1099: 1091: 1089:0-387-97716-3 1085: 1081: 1076: 1075: 1066: 1065:conic section 1062: 1058: 1055: 1051: 1047: 1044: 1040: 1036: 1032: 1029: 1025: 1021: 1017: 1013: 1009: 1005: 1001: 997: 993: 989: 985: 982: 978: 975: 971: 967: 950: 946: 942: 939: 936: 914: 904: 900: 896: 893: 890: 879: 860: 857: 854: 851: 848: 842: 839: 831: 827: 823: 820: 817: 811: 789: 785: 781: 778: 775: 767: 766: 765: 757: 755: 751: 746: 745:, and so on. 744: 740: 736: 717: 714: 711: 708: 705: 702: 699: 694: 690: 682: 666: 662: 658: 655: 652: 649: 644: 640: 632: 616: 612: 608: 605: 602: 599: 594: 590: 582: 581: 580: 579: 575: 571: 552: 549: 546: 543: 540: 537: 534: 523: 519: 514: 495: 491: 487: 482: 478: 474: 471: 461: 457: 433: 429: 425: 420: 416: 412: 409: 400: 397: 394: 387: 386: 385: 384: 380: 361: 353: 349: 345: 340: 336: 332: 329: 326: 321: 317: 313: 308: 304: 291: 288: 285: 279: 276: 269: 268: 267: 250: 247: 244: 234: 213: 198: 188: 185: 178: 177: 176: 174: 166: 157: 155: 151: 147: 144:, and is the 143: 139: 135: 131: 127: 123: 119: 115: 111: 108: 104: 100: 97: 94:is a smooth, 93: 92:twisted cubic 89: 78: 75: 67: 64:February 2022 57: 53: 47: 46: 40: 36: 32: 27: 18: 17: 1652: 1629:Prym variety 1603:Stable curve 1593:Hodge bundle 1583:ELSV formula 1385:Fermat curve 1342:Plane curves 1305:Higher genus 1280:Applications 1205:Modular form 1164: 1079: 1060: 1049: 1038: 1034: 1027: 1007: 1003: 996:secant lines 980: 973: 969: 763: 753: 747: 742: 738: 732: 569: 515: 460:affine curve 453: 383:moment curve 376: 230: 170: 150:Veronese map 134:hypersurface 121: 109: 98: 91: 85: 70: 61: 50:Please help 42: 1658:singularity 1504:Polar curve 88:mathematics 56:introducing 1499:Dual curve 1127:Topics in 1072:References 760:Properties 266:the value 160:Definition 114:skew curve 1612:Morphisms 1360:Bitangent 1063:yields a 1052:yields a 1041:yields a 943:− 897:− 880:, since 855:− 840:− 824:− 782:− 709:− 659:− 609:− 574:subscheme 404:↦ 395:ν 298:↦ 277:ν 204:→ 186:ν 105:three in 1730:Category 1006:fill up 965:is not). 522:quadrics 1683:Tacnode 1668:Crunode 1012:tangent 992:tangent 990:of the 878:radical 458:of the 377:In one 52:improve 1663:Acnode 1576:Moduli 1086:  1056:cubic. 1016:secant 103:degree 1054:nodal 998:(the 988:union 972:span 148:of a 146:image 37:, or 1673:Cusp 1084:ISBN 1014:and 994:and 986:The 804:and 741:for 90:, a 568:on 122:the 101:of 86:In 1732:: 513:. 156:. 41:, 33:, 1655:k 1653:A 1120:e 1113:t 1106:v 1093:. 1067:. 1061:C 1050:C 1045:. 1039:C 1035:C 1028:P 1008:P 1004:C 981:P 976:. 974:P 970:C 951:2 947:Z 940:W 937:Y 915:2 911:) 905:2 901:Z 894:W 891:Y 888:( 864:) 861:Z 858:Y 852:W 849:X 846:( 843:W 837:) 832:2 828:Z 821:W 818:Y 815:( 812:Z 790:2 786:Y 779:Z 776:X 754:C 743:X 739:x 718:. 715:Z 712:Y 706:W 703:X 700:= 695:2 691:F 667:2 663:Z 656:W 653:Y 650:= 645:1 641:F 617:2 613:Y 606:Z 603:X 600:= 595:0 591:F 570:P 556:] 553:W 550:: 547:Z 544:: 541:Y 538:: 535:X 532:[ 501:) 496:3 492:x 488:, 483:2 479:x 475:, 472:x 469:( 439:) 434:3 430:x 426:, 421:2 417:x 413:, 410:x 407:( 401:x 398:: 362:. 359:] 354:3 350:T 346:: 341:2 337:T 333:S 330:: 327:T 322:2 318:S 314:: 309:3 305:S 301:[ 295:] 292:T 289:: 286:S 283:[ 280:: 254:] 251:T 248:: 245:S 242:[ 214:3 209:P 199:1 194:P 189:: 120:( 110:P 99:C 77:) 71:( 66:) 62:( 48:.

Index

list of references
related reading
external links
inline citations
improve
introducing
Learn how and when to remove this message
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
quadrics

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