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Bimodule

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1439: 1227: 1296: 1146: 184: 39:, bimodules play a clarifying role, in the sense that many of the relationships between left and right modules become simpler when they are expressed in terms of bimodules. 996:
modules. Using these facts, many definitions and statements about modules can be immediately translated into definitions and statements about bimodules. For example, the
1444:
holds whenever either (and hence the other) side of the equation is defined, and where ∘ is the usual composition of homomorphisms. In this interpretation, the category
1338: 981:(where the multiplication is defined with the arguments exchanged). Bimodule homomorphisms are the same as homomorphisms of left 1091:), and one can hence construct a category whose objects are the rings and whose morphisms are the bimodules. This is in fact a 563:
is a left module, we can define multiplication on the right to be the same as multiplication on the left. (However, not all
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by taking the left and right actions to be multiplication – the actions commute by associativity. This can be extended to
124: 1770: 35:, such that the left and right multiplications are compatible. Besides appearing naturally in many parts of 1157: 1233: 328:; the heights and widths of the matrices have been chosen so that multiplication is defined. Note that 1119: 1568: 1023: 1589: 1789: 997: 1022:
There are however some new effects in the world of bimodules, especially when it comes to the
325: 1016: 403:, is the statement that multiplication of matrices is associative (which, in the case of a 248: 32: 8: 1543: 531: 1739: 1738:
Street, Ross (20 Mar 2003). "Categorical and combinatorial aspects of descent theory".
56: 598: 1766: 1642: 1468: 1495: 1012: 553: 520: 20: 1758: 1686: 321: 1332:. One immediately verifies the interchange law for bimodule homomorphisms, i.e. 549:, with the ring multiplication both as the left and as the right multiplication. 1483: 1434:{\displaystyle (f'\otimes g')\circ (f\otimes g)=(f'\circ f)\otimes (g'\circ g)} 320:
matrices. Addition and multiplication are carried out using the usual rules of
660:
is a ring with the multiplication given by composition. The endomorphism ring
1783: 974: 567:-bimodules arise this way: other compatible right multiplications may exist.) 408: 28: 657: 1693: 1689: 1088: 1080: 404: 252: 36: 1549:
is a motivating example of a symmetric monoidal category, in which case
1718: 1699: 1092: 1744: 1706: 954:-bimodule is actually the same thing as a left module over the ring 795: 211: 16:
Abelian group equipped with compatible ring action on both sides
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matrix is not defined. The crucial bimodule property, that
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can be seen as a categorical generalization of bimodules.
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in a natural fashion. This tensor product of bimodules is
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has the natural structure of a bimodule. For example, if
426:-bimodule, with left and right multiplication defined by 1490:
the tensor product of the category. In particular, if
1685:
in a natural fashion. These statements extend to the
1341: 1236: 1160: 1122: 127: 1513:, which gives a monoidal embedding of the category 1113:are exactly bimodule homomorphisms, i.e. functions 1433: 1290: 1221: 1140: 178: 1781: 1765:. W. H. Freeman and Company. pp. 133–136. 1705:Note that bimodules are not at all related to 1584:giving the monoidal structure, and with unit 1757: 896: 1095:, in a canonical way – 2 morphisms between 1743: 616:. Any abelian group may be treated as a 1782: 1737: 935:if it is both a homomorphism of left 1731: 13: 1222:{\displaystyle f(m+m')=f(m)+f(m')} 678:by left multiplication defined by 500:itself can be considered to be an 14: 1801: 1291:{\displaystyle f(r.m.s)=r.f(m).s} 1575:, with the usual tensor product 1141:{\displaystyle f:M\rightarrow N} 422:has the natural structure of an 179:{\displaystyle (r.m).s=r.(m.s).} 31:that is both a left and a right 737:to itself. Therefore any right 605:-modules may be interpreted as 345:) itself is not a ring (unless 1428: 1411: 1405: 1388: 1382: 1370: 1364: 1342: 1279: 1273: 1258: 1240: 1216: 1205: 1196: 1190: 1181: 1164: 1132: 762:-bimodule. Similarly any left 697:. The bimodule property, that 481:is the canonical embedding of 197:-bimodule is also known as an 170: 158: 140: 128: 1: 1724: 1056:, then the tensor product of 42: 7: 1712: 1666:-module homomorphisms from 204: 10: 1806: 1611:-algebra. Furthermore, if 1502:-module is canonically an 733:-module homomorphism from 355:), because multiplying an 1569:category of vector spaces 1019:are valid for bimodules. 897:Further notions and facts 917:-bimodules, then a map 1498:, every left or right 1435: 1292: 1223: 1142: 939:-modules and of right 638:-module, then the set 180: 1588:. We also see that a 1436: 1293: 1224: 1143: 1064:(taken over the ring 933:bimodule homomorphism 326:matrix multiplication 181: 1339: 1234: 1158: 1120: 1017:isomorphism theorems 467:respectively, where 125: 90:-module and a right 71:is an abelian group 1087:a unique canonical 1015:, and the standard 601:. Similarly, right 1431: 1288: 1219: 1138: 552:Any module over a 365:matrix by another 176: 1469:monoidal category 407:, corresponds to 1797: 1776: 1763:Basic Algebra II 1750: 1749: 1747: 1735: 1687:derived functors 1684: 1661: 1640: 1625: 1606: 1583: 1566: 1538:. The case that 1537: 1522: 1512: 1496:commutative ring 1481: 1466: 1440: 1438: 1437: 1432: 1421: 1398: 1363: 1352: 1331: 1321: 1311: 1297: 1295: 1294: 1289: 1228: 1226: 1225: 1220: 1215: 1180: 1147: 1145: 1144: 1139: 1105: 1078: 1055: 1040: 1010: 995: 968: 930: 883: 868: 838: 827: 817:. It is also an 816: 786: 761: 725:, restates that 724: 696: 673: 651: 626: 615: 599:ring of integers 592: 554:commutative ring 548: 510: 496:is a ring, then 480: 466: 447: 402: 374: 364: 354: 319: 292: 265: 247: 185: 183: 182: 177: 78: 21:abstract algebra 1805: 1804: 1800: 1799: 1798: 1796: 1795: 1794: 1780: 1779: 1773: 1754: 1753: 1736: 1732: 1727: 1715: 1675: 1651: 1645: 1631: 1616: 1593: 1582: 1576: 1550: 1524: 1514: 1503: 1482:with the usual 1472: 1467:is exactly the 1445: 1414: 1391: 1356: 1345: 1340: 1337: 1336: 1323: 1313: 1303: 1235: 1232: 1231: 1208: 1173: 1159: 1156: 1155: 1121: 1118: 1117: 1096: 1069: 1046: 1031: 1001: 991: 982: 964: 955: 918: 899: 879: 870: 859: 829: 818: 807: 780: 771: 752: 746: 698: 679: 667: 661: 645: 639: 617: 606: 583: 539: 501: 468: 449: 427: 376: 366: 356: 346: 340: 322:matrix addition 311: 305: 284: 278: 256: 239: 233: 207: 126: 123: 122: 72: 45: 17: 12: 11: 5: 1803: 1793: 1792: 1778: 1777: 1771: 1752: 1751: 1729: 1728: 1726: 1723: 1722: 1721: 1714: 1711: 1647: 1607:is exactly an 1578: 1484:tensor product 1442: 1441: 1430: 1427: 1424: 1420: 1417: 1413: 1410: 1407: 1404: 1401: 1397: 1394: 1390: 1387: 1384: 1381: 1378: 1375: 1372: 1369: 1366: 1362: 1359: 1355: 1351: 1348: 1344: 1300: 1299: 1287: 1284: 1281: 1278: 1275: 1272: 1269: 1266: 1263: 1260: 1257: 1254: 1251: 1248: 1245: 1242: 1239: 1229: 1218: 1214: 1211: 1207: 1204: 1201: 1198: 1195: 1192: 1189: 1186: 1183: 1179: 1176: 1172: 1169: 1166: 1163: 1149: 1148: 1137: 1134: 1131: 1128: 1125: 1024:tensor product 987: 960: 898: 895: 894: 893: 875: 854:-bimodule and 840: 788: 776: 748: 663: 641: 628: 578:-module, then 568: 550: 530:Any two-sided 528: 521:direct product 490: 412: 332: 301: 293:matrices, and 274: 225: 206: 203: 187: 186: 175: 172: 169: 166: 163: 160: 157: 154: 151: 148: 145: 142: 139: 136: 133: 130: 95: 44: 41: 15: 9: 6: 4: 3: 2: 1802: 1791: 1790:Module theory 1788: 1787: 1785: 1774: 1772:0-7167-1933-9 1768: 1764: 1760: 1756: 1755: 1746: 1741: 1734: 1730: 1720: 1717: 1716: 1710: 1708: 1703: 1701: 1697: 1695: 1691: 1688: 1682: 1678: 1673: 1669: 1665: 1659: 1655: 1650: 1644: 1638: 1634: 1629: 1623: 1619: 1614: 1610: 1604: 1600: 1596: 1591: 1587: 1581: 1574: 1570: 1565: 1561: 1557: 1553: 1548: 1545: 1541: 1535: 1531: 1527: 1521: 1517: 1510: 1506: 1501: 1497: 1493: 1489: 1485: 1479: 1475: 1470: 1464: 1460: 1456: 1452: 1448: 1425: 1422: 1418: 1415: 1408: 1402: 1399: 1395: 1392: 1385: 1379: 1376: 1373: 1367: 1360: 1357: 1353: 1349: 1346: 1335: 1334: 1333: 1330: 1326: 1320: 1316: 1310: 1306: 1285: 1282: 1276: 1270: 1267: 1264: 1261: 1255: 1252: 1249: 1246: 1243: 1237: 1230: 1212: 1209: 1202: 1199: 1193: 1187: 1184: 1177: 1174: 1170: 1167: 1161: 1154: 1153: 1152: 1151:that satisfy 1135: 1129: 1126: 1123: 1116: 1115: 1114: 1112: 1108: 1103: 1099: 1094: 1090: 1086: 1082: 1076: 1072: 1067: 1063: 1059: 1053: 1049: 1044: 1038: 1034: 1029: 1025: 1020: 1018: 1014: 1008: 1004: 999: 994: 990: 985: 980: 976: 975:opposite ring 972: 967: 963: 958: 953: 949: 944: 942: 938: 934: 929: 925: 921: 916: 912: 908: 904: 891: 887: 882: 878: 873: 866: 862: 857: 853: 849: 845: 841: 836: 832: 825: 821: 814: 810: 805: 801: 797: 793: 789: 784: 779: 774: 769: 765: 760: 756: 751: 744: 740: 736: 732: 728: 722: 718: 714: 710: 706: 702: 694: 690: 686: 682: 677: 671: 666: 659: 658:endomorphisms 655: 649: 644: 637: 633: 629: 624: 620: 613: 609: 604: 600: 596: 590: 586: 581: 577: 573: 569: 566: 562: 558: 555: 551: 546: 542: 537: 533: 529: 526: 522: 518: 514: 508: 504: 499: 495: 491: 488: 484: 479: 475: 471: 464: 460: 456: 452: 446: 442: 438: 434: 430: 425: 421: 417: 413: 410: 409:associativity 406: 400: 396: 392: 388: 384: 380: 373: 369: 363: 359: 353: 349: 344: 339: 335: 331: 327: 323: 318: 314: 309: 304: 300: 296: 291: 287: 282: 277: 273: 269: 263: 259: 254: 250: 246: 242: 237: 232: 228: 224: 220: 216: 213: 210:For positive 209: 208: 202: 200: 196: 192: 173: 167: 164: 161: 155: 152: 149: 146: 143: 137: 134: 131: 120: 116: 112: 108: 104: 100: 96: 93: 89: 85: 82: 81: 80: 76: 70: 66: 62: 58: 54: 50: 40: 38: 34: 30: 29:abelian group 26: 22: 1762: 1759:Jacobson, N. 1745:math/0303175 1733: 1704: 1698: 1680: 1676: 1671: 1667: 1663: 1657: 1653: 1648: 1636: 1632: 1627: 1621: 1617: 1612: 1608: 1602: 1598: 1594: 1585: 1579: 1572: 1563: 1559: 1555: 1551: 1546: 1539: 1533: 1529: 1525: 1519: 1515: 1508: 1504: 1499: 1491: 1487: 1477: 1473: 1462: 1458: 1454: 1450: 1446: 1443: 1328: 1324: 1318: 1314: 1308: 1304: 1301: 1150: 1110: 1106: 1101: 1097: 1074: 1070: 1065: 1061: 1057: 1051: 1047: 1042: 1036: 1032: 1027: 1021: 1006: 1002: 992: 988: 983: 978: 970: 965: 961: 956: 951: 947: 945: 940: 936: 932: 927: 923: 919: 914: 910: 906: 902: 900: 889: 885: 880: 876: 871: 864: 860: 855: 851: 847: 843: 834: 830: 823: 819: 812: 808: 803: 799: 791: 782: 777: 772: 767: 763: 758: 754: 749: 742: 738: 734: 730: 726: 720: 716: 712: 708: 704: 700: 692: 688: 684: 680: 675: 669: 664: 653: 647: 642: 635: 631: 622: 618: 611: 607: 602: 594: 588: 584: 579: 575: 571: 564: 560: 556: 544: 540: 535: 524: 516: 512: 506: 502: 497: 493: 486: 482: 477: 473: 469: 462: 458: 454: 450: 444: 440: 436: 432: 428: 423: 419: 418:over a ring 415: 414:Any algebra 398: 394: 390: 386: 382: 378: 371: 367: 361: 357: 351: 347: 342: 337: 333: 329: 316: 312: 307: 302: 298: 297:is the ring 294: 289: 285: 280: 275: 271: 270:is the ring 267: 261: 257: 253:real numbers 244: 240: 235: 230: 226: 222: 218: 214: 198: 194: 190: 188: 118: 114: 110: 106: 102: 98: 91: 87: 83: 74: 68: 64: 60: 52: 48: 46: 24: 18: 1700:Profunctors 1641:, then the 1089:isomorphism 1081:associative 634:is a right 405:matrix ring 201:-bimodule. 79:such that: 37:mathematics 1725:References 1719:Profunctor 1707:bialgebras 1674:becomes a 1480:-bimodules 1104:-bimodules 1093:2-category 1009:-bimodules 943:-modules. 892:-bimodule. 787:-bimodule. 614:-bimodules 574:is a left 534:of a ring 221:, the set 86:is a left 59:, then an 43:Definition 1683:-bimodule 1639:-bimodule 1624:-bimodule 1511:-bimodule 1423:∘ 1409:⊗ 1400:∘ 1377:⊗ 1368:∘ 1354:⊗ 1133:→ 1077:-bimodule 1054:-bimodule 1039:-bimodule 867:-bimodule 837:-bimodule 815:-bimodule 625:-bimodule 591:-bimodule 547:-bimodule 509:-bimodule 264:-bimodule 1784:Category 1761:(1989). 1713:See also 1419:′ 1396:′ 1361:′ 1350:′ 1213:′ 1178:′ 1068:) is an 998:category 969:, where 922: : 766:-module 741:-module 674:acts on 656:-module 593:, where 472: : 266:, where 249:matrices 212:integers 205:Examples 97:For all 94:-module. 69:bimodule 55:are two 25:bimodule 1662:of all 1013:abelian 1000:of all 973:is the 869:, then 828:and an 802:, then 796:subring 597:is the 1769:  1630:is an 1615:is an 1590:monoid 1567:, the 1322:, and 1045:is an 1030:is an 884:is an 858:is an 846:is an 806:is an 770:is an 745:is an 729:is a 582:is an 538:is an 519:-fold 255:is an 33:module 27:is an 1740:arXiv 1595:Bimod 1577:⊗ = ⊗ 1571:over 1544:field 1542:is a 1526:Bimod 1523:into 1494:is a 1486:over 1455:Bimod 1085:up to 1026:: if 931:is a 794:is a 532:ideal 515:(the 485:into 310:) of 283:) of 238:) of 57:rings 1767:ISBN 1692:and 1626:and 1564:Vect 1453:) = 1302:for 1109:and 1060:and 1041:and 909:are 905:and 775:-End 448:and 324:and 217:and 113:and 77:, +) 51:and 23:, a 1694:Tor 1690:Ext 1670:to 1646:Hom 1643:set 1592:in 1556:Mod 1520:Mod 1471:of 1447:End 1011:is 977:of 946:An 901:If 842:If 798:of 790:If 747:End 662:End 652:of 640:End 630:If 570:If 523:of 492:If 251:of 189:An 117:in 109:in 101:in 47:If 19:In 1786:: 1709:. 1696:. 1656:, 1601:, 1558:= 1532:, 1461:, 1327:∈ 1317:∈ 1312:, 1307:∈ 926:→ 757:)- 715:.( 711:= 707:). 687:= 527:). 476:→ 459:aφ 457:= 435:= 411:). 393:.( 389:= 385:). 370:× 360:× 350:= 315:× 288:× 243:× 121:: 105:, 1775:. 1748:. 1742:: 1681:R 1679:- 1677:T 1672:L 1668:M 1664:S 1660:) 1658:L 1654:M 1652:( 1649:S 1637:S 1635:- 1633:T 1628:L 1622:S 1620:- 1618:R 1613:M 1609:R 1605:) 1603:R 1599:R 1597:( 1586:K 1580:K 1573:K 1562:- 1560:K 1554:- 1552:R 1547:K 1540:R 1536:) 1534:R 1530:R 1528:( 1518:- 1516:R 1509:R 1507:- 1505:R 1500:R 1492:R 1488:R 1478:R 1476:- 1474:R 1465:) 1463:R 1459:R 1457:( 1451:R 1449:( 1429:) 1426:g 1416:g 1412:( 1406:) 1403:f 1393:f 1389:( 1386:= 1383:) 1380:g 1374:f 1371:( 1365:) 1358:g 1347:f 1343:( 1329:S 1325:s 1319:R 1315:r 1309:M 1305:m 1298:, 1286:s 1283:. 1280:) 1277:m 1274:( 1271:f 1268:. 1265:r 1262:= 1259:) 1256:s 1253:. 1250:m 1247:. 1244:r 1241:( 1238:f 1217:) 1210:m 1206:( 1203:f 1200:+ 1197:) 1194:m 1191:( 1188:f 1185:= 1182:) 1175:m 1171:+ 1168:m 1165:( 1162:f 1136:N 1130:M 1127:: 1124:f 1111:N 1107:M 1102:S 1100:- 1098:R 1083:( 1075:T 1073:- 1071:R 1066:S 1062:N 1058:M 1052:T 1050:- 1048:S 1043:N 1037:S 1035:- 1033:R 1028:M 1007:S 1005:- 1003:R 993:S 989:Z 986:⊗ 984:R 979:S 971:S 966:S 962:Z 959:⊗ 957:R 952:S 950:- 948:R 941:S 937:R 928:N 924:M 920:f 915:S 913:- 911:R 907:N 903:M 890:T 888:- 886:S 881:N 877:R 874:⊗ 872:M 865:T 863:- 861:R 856:N 852:R 850:- 848:S 844:M 839:. 835:R 833:- 831:S 826:- 824:S 822:- 820:R 813:R 811:- 809:R 804:S 800:S 792:R 785:) 783:N 781:( 778:R 773:R 768:N 764:R 759:R 755:M 753:( 750:R 743:M 739:R 735:M 731:R 727:f 723:) 721:r 719:. 717:x 713:f 709:r 705:x 703:. 701:f 699:( 695:) 693:x 691:( 689:f 685:x 683:. 681:f 676:M 672:) 670:M 668:( 665:R 654:R 650:) 648:M 646:( 643:R 636:R 632:M 627:. 623:Z 621:- 619:Z 612:R 610:- 608:Z 603:R 595:Z 589:Z 587:- 585:R 580:M 576:R 572:M 565:R 561:M 557:R 545:R 543:- 541:R 536:R 525:R 517:n 513:R 507:R 505:- 503:R 498:R 494:R 489:. 487:A 483:R 478:A 474:R 470:φ 465:) 463:r 461:( 455:r 453:. 451:a 445:a 443:) 441:r 439:( 437:φ 433:a 431:. 429:r 424:R 420:R 416:A 401:) 399:s 397:. 395:x 391:r 387:s 383:x 381:. 379:r 377:( 372:m 368:n 362:m 358:n 352:m 348:n 343:R 341:( 338:m 336:, 334:n 330:M 317:m 313:m 308:R 306:( 303:m 299:M 295:S 290:n 286:n 281:R 279:( 276:n 272:M 268:R 262:S 260:- 258:R 245:m 241:n 236:R 234:( 231:m 229:, 227:n 223:M 219:m 215:n 199:R 195:R 193:- 191:R 174:. 171:) 168:s 165:. 162:m 159:( 156:. 153:r 150:= 147:s 144:. 141:) 138:m 135:. 132:r 129:( 119:M 115:m 111:S 107:s 103:R 99:r 92:S 88:R 84:M 75:M 73:( 67:- 65:S 63:- 61:R 53:S 49:R

Index

abstract algebra
abelian group
module
mathematics
rings
integers
matrices
real numbers
matrix addition
matrix multiplication
matrix ring
associativity
direct product
ideal
commutative ring
ring of integers
endomorphisms
subring
opposite ring
category
abelian
isomorphism theorems
tensor product
associative
up to
isomorphism
2-category
monoidal category
tensor product
commutative ring

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