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Chain (algebraic topology)

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482: 441: 1336: 812: 1331:{\displaystyle {\begin{aligned}\partial _{1}c&=\partial _{1}(t_{1}+t_{2}+t_{3})\\&=\partial _{1}(t_{1})+\partial _{1}(t_{2})+\partial _{1}(t_{3})\\&=\partial _{1}()+\partial _{1}()+\partial _{1}()\\&=(-)+(-)+(-)\\&=-.\end{aligned}}} 305: 817: 497:−1)-chain. Note that the boundary of a simplex is not a simplex, but a chain with coefficients 1 or −1 – thus chains are the closure of simplices under the boundary operator. 569: 424:
Integration is defined on chains by taking the linear combination of integrals over the simplices in the chain with coefficients (which are typically integers). The set of all
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The boundary of the triangle is a formal sum of its edges with signs arranged to make the traversal of the boundary counterclockwise.
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The plane punctured at the origin has nontrivial 1-homology group since the unit circle is a cycle, but not a boundary.
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The boundary of a chain is the linear combination of boundaries of the simplices in the chain. The boundary of a
514: 1517: 1413: 58: 312: 1359: 300:{\displaystyle C_{n}(X)=\left\{\sum \limits _{i}m_{i}\sigma _{i}|m_{i}\in \mathbb {Z} \right\}} 93: 750: 690: 630: 383: 130: 1375: 602: 574: 1497: 62: 39: 8: 1379: 1383: 363: 341: 186: 166: 110: 105: 73: 46: 31: 1407: 1350:
when its boundary is zero. A chain that is the boundary of another chain is called a
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is a linear combination of its nodes; in this case, some linear combination of A
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A closed polygonal curve, assuming consistent orientation, has null boundary.
429: 1474:. Applied Mathematical Sciences. Vol. 157. New York: Springer-Verlag. 35: 1358:, whose homology groups (cycles modulo boundaries) are called simplicial 481: 69: 96:; the elements of a homology group are equivalence classes of chains. 1479: 428:-chains forms a group and the sequence of these groups is called a 1470:
Kaczynski, Tomasz; Mischaikow, Konstantin; Mrozek, Marian (2004).
1378:, the duality between the boundary operator on chains and the 440: 92:-cubes), but not necessarily connected. Chains are used in 1469: 815: 753: 693: 633: 605: 577: 517: 386: 366: 344: 315: 211: 189: 169: 133: 113: 416:
not necessary to be a connected simplicial complex.
507:is the formal difference of its endpoints: it is a 1330: 799: 739: 679: 619: 591: 563: 408: 372: 350: 328: 299: 195: 175: 155: 119: 1509: 435: 1354:. Boundaries are cycles, so chains form a 796: 736: 676: 616: 588: 560: 288: 480: 439: 419: 1402: 14: 1510: 807:are its constituent 1-simplices, then 1439:Introduction to topological manifolds 564:{\displaystyle c=t_{1}+t_{2}+t_{3}\,} 1441:(2nd ed.). New York: Springer. 1436: 240: 24: 1093: 1045: 997: 961: 932: 903: 841: 821: 25: 1534: 511:. To illustrate, if the 1-chain 1463: 1430: 1396: 1318: 1305: 1299: 1286: 1273: 1270: 1257: 1251: 1238: 1235: 1229: 1226: 1213: 1207: 1194: 1191: 1185: 1182: 1169: 1163: 1150: 1147: 1134: 1131: 1105: 1102: 1086: 1083: 1057: 1054: 1038: 1035: 1009: 1006: 983: 970: 954: 941: 925: 912: 889: 850: 793: 767: 733: 707: 673: 647: 403: 397: 270: 228: 222: 150: 144: 13: 1: 1389: 99: 1382:is expressed by the general 84:-chains are combinations of 7: 436:Boundary operator on chains 329:{\displaystyle \sigma _{i}} 27:A formal linear combination 10: 1539: 1414:Cambridge University Press 88:-simplices (respectively, 29: 59:formal linear combination 1523:Integration on manifolds 800:{\displaystyle t_{3}=\,} 740:{\displaystyle t_{2}=\,} 680:{\displaystyle t_{1}=\,} 409:{\displaystyle C_{n}(X)} 156:{\displaystyle C_{n}(X)} 34:. For the term chain in 18:Boundary (chain complex) 620:{\displaystyle v_{4}\,} 592:{\displaystyle v_{1}\,} 1472:Computational homology 1332: 801: 741: 681: 621: 593: 565: 486: 478: 410: 380:. that any element in 374: 352: 330: 301: 197: 177: 157: 121: 30:This article is about 1437:Lee, John M. (2011). 1376:differential geometry 1333: 802: 742: 682: 622: 594: 571:is a path from point 566: 484: 443: 420:Integration on chains 411: 375: 353: 331: 302: 198: 178: 158: 122: 1346:A chain is called a 813: 751: 691: 631: 603: 575: 515: 469:), the boundary is A 384: 364: 342: 313: 209: 187: 167: 131: 111: 74:simplicial complexes 40:chain (order theory) 1380:exterior derivative 1518:Algebraic topology 1409:Algebraic Topology 1328: 1326: 797: 737: 677: 617: 589: 561: 503:The boundary of a 487: 479: 444:The boundary of a 406: 370: 348: 326: 297: 248: 193: 173: 153: 117: 106:simplicial complex 47:algebraic topology 32:algebraic topology 373:{\displaystyle X} 351:{\displaystyle n} 239: 196:{\displaystyle X} 176:{\displaystyle n} 120:{\displaystyle X} 78:cubical complexes 16:(Redirected from 1530: 1502: 1501: 1467: 1461: 1460: 1434: 1428: 1427: 1400: 1337: 1335: 1334: 1329: 1327: 1317: 1316: 1298: 1297: 1279: 1269: 1268: 1250: 1249: 1225: 1224: 1206: 1205: 1181: 1180: 1162: 1161: 1140: 1130: 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1448:978-1441979391 1447: 1429: 1422: 1404:Hatcher, Allen 1394: 1393: 1391: 1388: 1323: 1320: 1315: 1311: 1307: 1304: 1301: 1296: 1292: 1288: 1285: 1282: 1280: 1278: 1275: 1272: 1267: 1263: 1259: 1256: 1253: 1248: 1244: 1240: 1237: 1234: 1231: 1228: 1223: 1219: 1215: 1212: 1209: 1204: 1200: 1196: 1193: 1190: 1187: 1184: 1179: 1175: 1171: 1168: 1165: 1160: 1156: 1152: 1149: 1146: 1143: 1141: 1139: 1136: 1133: 1128: 1124: 1120: 1115: 1111: 1107: 1104: 1099: 1095: 1091: 1088: 1085: 1080: 1076: 1072: 1067: 1063: 1059: 1056: 1051: 1047: 1043: 1040: 1037: 1032: 1028: 1024: 1019: 1015: 1011: 1008: 1003: 999: 995: 992: 990: 988: 985: 980: 976: 972: 967: 963: 959: 956: 951: 947: 943: 938: 934: 930: 927: 922: 918: 914: 909: 905: 901: 898: 896: 894: 891: 886: 882: 878: 873: 869: 865: 860: 856: 852: 847: 843: 839: 836: 834: 832: 827: 823: 819: 818: 795: 790: 786: 782: 777: 773: 769: 766: 761: 757: 735: 730: 726: 722: 717: 713: 709: 706: 701: 697: 675: 670: 666: 662: 657: 653: 649: 646: 641: 637: 613: 609: 585: 581: 557: 553: 549: 544: 540: 536: 531: 527: 523: 520: 474: 470: 463: 457: 453: 449: 437: 434: 421: 418: 405: 402: 399: 394: 390: 369: 347: 323: 319: 295: 290: 286: 281: 277: 272: 266: 262: 256: 252: 246: 242: 237: 233: 230: 227: 224: 219: 215: 192: 172: 152: 149: 146: 141: 137: 116: 101: 98: 89: 85: 81: 63: 50: 26: 9: 6: 4: 3: 2: 1535: 1524: 1521: 1519: 1516: 1515: 1513: 1499: 1495: 1491: 1489:0-387-40853-3 1485: 1481: 1477: 1473: 1466: 1458: 1454: 1450: 1444: 1440: 1433: 1425: 1423:0-521-79540-0 1419: 1415: 1411: 1410: 1405: 1399: 1395: 1387: 1385: 1381: 1377: 1372: 1370: 1366: 1363: 1361: 1357: 1356:chain complex 1353: 1349: 1344: 1342: 1338: 1321: 1313: 1309: 1302: 1294: 1290: 1283: 1281: 1265: 1261: 1254: 1246: 1242: 1232: 1221: 1217: 1210: 1202: 1198: 1188: 1177: 1173: 1166: 1158: 1154: 1144: 1142: 1126: 1122: 1118: 1113: 1109: 1097: 1089: 1078: 1074: 1070: 1065: 1061: 1049: 1041: 1030: 1026: 1022: 1017: 1013: 1001: 993: 991: 978: 974: 965: 957: 949: 945: 936: 928: 920: 916: 907: 899: 897: 884: 880: 876: 871: 867: 863: 858: 854: 845: 837: 835: 830: 825: 808: 788: 784: 780: 775: 771: 764: 759: 755: 728: 724: 720: 715: 711: 704: 699: 695: 668: 664: 660: 655: 651: 644: 639: 635: 611: 607: 583: 579: 555: 551: 547: 542: 538: 534: 529: 525: 521: 518: 510: 506: 502: 498: 496: 493:-chain is a ( 492: 483: 466: 460: 447: 442: 433: 431: 430:chain complex 427: 417: 400: 392: 388: 367: 359: 345: 321: 317: 307: 293: 284: 279: 275: 264: 260: 254: 250: 244: 235: 231: 225: 217: 213: 204: 203:is given by: 190: 170: 147: 139: 135: 114: 107: 97: 95: 79: 75: 71: 67: 60: 56: 48: 41: 37: 33: 19: 1471: 1465: 1438: 1432: 1408: 1398: 1373: 1368: 1367: 1364: 1351: 1347: 1345: 1340: 1339: 809: 500: 499: 494: 490: 488: 464: 458: 425: 423: 308: 205: 127:, the group 103: 70:cell complex 54: 44: 36:order theory 183:-chains of 1512:Categories 1390:References 1369:Example 3: 1341:Example 2: 501:Example 1: 358:-simplices 100:Definition 1457:697506452 1303:− 1255:− 1211:− 1167:− 1094:∂ 1046:∂ 998:∂ 962:∂ 933:∂ 904:∂ 842:∂ 822:∂ 627:, where 599:to point 473:− A 452:through A 338:singular 318:σ 285:∈ 261:σ 241:∑ 1406:(2002). 1362:groups. 1360:homology 1352:boundary 94:homology 1498:2028588 61:of the 1496:  1486:  1455:  1445:  1420:  309:where 104:For a 66:-cells 38:, see 1348:cycle 72:. In 68:in a 57:is a 55:chain 1484:ISBN 1453:OCLC 1443:ISBN 1418:ISBN 747:and 505:path 462:to A 336:are 49:, a 1476:doi 1374:In 360:of 163:of 80:), 45:In 1514:: 1494:MR 1492:. 1482:. 1451:. 1416:. 1412:. 1386:. 687:, 467:+1 432:. 1500:. 1478:: 1459:. 1426:. 1322:. 1319:] 1314:1 1310:v 1306:[ 1300:] 1295:4 1291:v 1287:[ 1284:= 1274:) 1271:] 1266:3 1262:v 1258:[ 1252:] 1247:4 1243:v 1239:[ 1236:( 1233:+ 1230:) 1227:] 1222:2 1218:v 1214:[ 1208:] 1203:3 1199:v 1195:[ 1192:( 1189:+ 1186:) 1183:] 1178:1 1174:v 1170:[ 1164:] 1159:2 1155:v 1151:[ 1148:( 1145:= 1135:) 1132:] 1127:4 1123:v 1119:, 1114:3 1110:v 1106:[ 1103:( 1098:1 1090:+ 1087:) 1084:] 1079:3 1075:v 1071:, 1066:2 1062:v 1058:[ 1055:( 1050:1 1042:+ 1039:) 1036:] 1031:2 1027:v 1023:, 1018:1 1014:v 1010:[ 1007:( 1002:1 994:= 984:) 979:3 975:t 971:( 966:1 958:+ 955:) 950:2 946:t 942:( 937:1 929:+ 926:) 921:1 917:t 913:( 908:1 900:= 890:) 885:3 881:t 877:+ 872:2 868:t 864:+ 859:1 855:t 851:( 846:1 838:= 831:c 826:1 794:] 789:4 785:v 781:, 776:3 772:v 768:[ 765:= 760:3 756:t 734:] 729:3 725:v 721:, 716:2 712:v 708:[ 705:= 700:2 696:t 674:] 669:2 665:v 661:, 656:1 652:v 648:[ 645:= 640:1 636:t 612:4 608:v 584:1 580:v 556:3 552:t 548:+ 543:2 539:t 535:+ 530:1 526:t 522:= 519:c 495:k 491:k 477:. 475:1 471:6 465:k 459:k 454:6 450:1 426:k 404:) 401:X 398:( 393:n 389:C 368:X 346:n 322:i 294:} 289:Z 280:i 276:m 271:| 265:i 255:i 251:m 245:i 236:{ 232:= 229:) 226:X 223:( 218:n 214:C 191:X 171:n 151:) 148:X 145:( 140:n 136:C 115:X 90:k 86:k 82:k 64:k 53:- 51:k 42:. 20:)

Index

Boundary (chain complex)
algebraic topology
order theory
chain (order theory)
algebraic topology
formal linear combination
k-cells
cell complex
simplicial complexes
cubical complexes
homology
simplicial complex
singular n {\displaystyle n} -simplices
chain complex

polygonal curve

path
telescoping sum
chain complex
homology
differential geometry
exterior derivative
Stokes' theorem
Hatcher, Allen
Algebraic Topology
Cambridge University Press
ISBN
0-521-79540-0
ISBN

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