Knowledge (XXG)

Subcategory

Source 📝

1349: 1596: 1616: 1606: 373: 799: 864: 839: 285: 993: 942: 660: 986: 1190: 1145: 1619: 1559: 1609: 1395: 1259: 1167: 867: 434: 224: 723:. A wide subcategory is typically not full: the only wide full subcategory of a category is that category itself. 20: 1568: 1212: 1150: 1073: 628: 608: 535: 1640: 1599: 1555: 1160: 979: 50: 750: 1155: 1137: 1362: 1128: 1108: 1031: 879: 39: 1244: 1083: 1056: 1051: 742: 483: 1400: 1348: 1278: 1274: 1078: 588: 464: 905: 1645: 1254: 1249: 1231: 1113: 1088: 449: 445: 438: 1563: 1500: 1488: 1390: 1315: 1310: 1268: 1264: 1046: 1041: 938: 453: 1524: 1410: 1385: 1320: 1305: 1300: 1239: 1068: 1036: 930: 735: 543: 420: 1436: 1002: 31: 1473: 844: 819: 1468: 1452: 1415: 1405: 1325: 922: 884: 368:{\displaystyle \mathrm {Hom} _{\mathcal {S}}(X,Y)=\mathrm {Hom} _{\mathcal {C}}(X,Y).} 1634: 1463: 1295: 1172: 1098: 927:
Proceedings of the International Conference on Category Theory, Como, Italy (CT 1990)
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with the same identities and composition of morphisms. Intuitively, a subcategory of
1217: 1118: 520: 475: 1478: 957: 1458: 1200: 716: 539: 27: 1510: 1448: 1061: 416: 1504: 1195: 639: 516: 427: 929:. Lecture Notes in Mathematics. Vol. 1488. Springer. pp. 95–104. 638:
In some categories, one can also speak of morphisms of the category being
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With the definitions of the previous paragraph, for any (full) embedding
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Category whose objects and morphisms are inside a bigger category
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to be a full and faithful functor that is injective on objects.
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is a category in its own right: its collection of objects is ob(
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forms a full subcategory of the category of (left or right)
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The category whose objects are sets and whose morphisms are
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is an embedding if it is injective on morphisms. A functor
538:. Such a functor is necessarily injective on objects up to 560:
if it is faithful and injective on objects. Equivalently,
696:. An isomorphism-closed full subcategory is said to be 847: 822: 753: 430:
forms a non-full subcategory of the category of sets.
288: 1523: 1487: 1435: 1428: 1379: 1288: 1230: 1181: 1136: 1127: 1024: 858: 833: 793: 456:) forms a non-full subcategory of the category of 367: 245:which takes objects and morphisms to themselves. 219:), and its identities and composition are as in 623:is not injective on objects then the image of 73:by "removing" some of its objects and arrows. 987: 925:(1991). "Algebraically complete categories". 887:, a full subcategory closed under extensions. 8: 1615: 1605: 1432: 1376: 1357: 1133: 1021: 1010: 994: 980: 972: 572:if it is a full functor and an embedding. 19:For subcategories on Knowledge (XXG), see 846: 821: 752: 340: 339: 328: 302: 301: 290: 287: 794:{\displaystyle 0\to M'\to M\to M''\to 0} 556:Other authors define a functor to be an 398:, there is a unique full subcategory of 378:A full subcategory is one that includes 896: 215:), its collection of morphisms is hom( 7: 719:) if it contains all the objects of 335: 332: 329: 297: 294: 291: 14: 1614: 1604: 1595: 1594: 1347: 730:is a non-empty full subcategory 437:forms a full subcategory of the 419:forms a full subcategory of the 390:. For any collection of objects 111:a subcollection of morphisms of 546:is an embedding in this sense. 515:is both a faithful functor and 252:be a subcategory of a category 785: 774: 768: 757: 359: 347: 321: 309: 100:a subcollection of objects of 1: 207:These conditions ensure that 21:Knowledge (XXG):Subcategories 866:do. This notion arises from 267:if for each pair of objects 179:for every pair of morphisms 69:is a category obtained from 1289:Constructions on categories 402:whose objects are those in 135:), the identity morphism id 1662: 1396:Higher-dimensional algebra 435:category of abelian groups 18: 1590: 1369: 1356: 1345: 1020: 1009: 609:isomorphism of categories 536:full and faithful functor 203:) whenever it is defined. 595:is a (full) subcategory 503:, the inclusion functor 1206:Cokernels and quotients 1129:Universal constructions 906:"Basic category theory" 715:(a term first posed by 549:Some authors define an 530:Some authors define an 527:is a full subcategory. 1363:Higher category theory 1109:Natural transformation 880:Reflective subcategory 860: 835: 795: 646:Types of subcategories 369: 223:. There is an obvious 861: 836: 796: 743:short exact sequences 668:if every isomorphism 448:(whose morphisms are 370: 1232:Algebraic categories 845: 820: 816:if and only if both 751: 542:. For instance, the 495:Given a subcategory 286: 1401:Homotopy hypothesis 1079:Commutative diagram 859:{\displaystyle M''} 386:between objects of 262:full subcategory of 164:), both the source 148:for every morphism 1114:Universal property 935:10.1007/BFb0084215 856: 834:{\displaystyle M'} 831: 791: 741:such that for all 661:isomorphism-closed 519:on objects. It is 470:, the category of 454:ring homomorphisms 439:category of groups 365: 1628: 1627: 1586: 1585: 1582: 1581: 1564:monoidal category 1519: 1518: 1391:Enriched category 1343: 1342: 1339: 1338: 1316:Quotient category 1311:Opposite category 1226: 1225: 944:978-3-540-54706-8 904:Jaap van Oosten. 728:Serre subcategory 703:A subcategory of 568:is then called a 243:inclusion functor 85:be a category. A 77:Formal definition 61:are morphisms in 1653: 1618: 1617: 1608: 1607: 1598: 1597: 1433: 1411:Simplex category 1386:Categorification 1377: 1358: 1351: 1321:Product category 1306:Kleisli category 1301:Functor category 1146:Terminal objects 1134: 1069:Adjoint functors 1022: 1011: 996: 989: 982: 973: 967: 958:Wide subcategory 955: 949: 948: 919: 913: 912: 910: 901: 868:Serre's C-theory 865: 863: 862: 857: 855: 840: 838: 837: 832: 830: 800: 798: 797: 792: 784: 767: 736:abelian category 692:also belongs to 544:Yoneda embedding 444:The category of 421:category of sets 415:The category of 374: 372: 371: 366: 346: 345: 344: 338: 308: 307: 306: 300: 191:) the composite 1661: 1660: 1656: 1655: 1654: 1652: 1651: 1650: 1641:Category theory 1631: 1630: 1629: 1624: 1578: 1548: 1515: 1492: 1483: 1440: 1424: 1375: 1365: 1352: 1335: 1284: 1222: 1191:Initial objects 1177: 1123: 1016: 1005: 1003:Category theory 1000: 970: 956: 952: 945: 921: 920: 916: 908: 903: 902: 898: 894: 876: 848: 843: 842: 823: 818: 817: 777: 760: 749: 748: 648: 523:if and only if 493: 412: 327: 289: 284: 283: 168:and the target 140: 79: 53:are objects in 32:category theory 30:, specifically 24: 17: 12: 11: 5: 1659: 1657: 1649: 1648: 1643: 1633: 1632: 1626: 1625: 1623: 1622: 1612: 1602: 1591: 1588: 1587: 1584: 1583: 1580: 1579: 1577: 1576: 1571: 1566: 1552: 1546: 1541: 1536: 1530: 1528: 1521: 1520: 1517: 1516: 1514: 1513: 1508: 1497: 1495: 1490: 1485: 1484: 1482: 1481: 1476: 1471: 1466: 1461: 1456: 1445: 1443: 1438: 1430: 1426: 1425: 1423: 1418: 1416:String diagram 1413: 1408: 1406:Model category 1403: 1398: 1393: 1388: 1383: 1381: 1374: 1373: 1370: 1367: 1366: 1361: 1354: 1353: 1346: 1344: 1341: 1340: 1337: 1336: 1334: 1333: 1328: 1326:Comma category 1323: 1318: 1313: 1308: 1303: 1298: 1292: 1290: 1286: 1285: 1283: 1282: 1272: 1262: 1260:Abelian groups 1257: 1252: 1247: 1242: 1236: 1234: 1228: 1227: 1224: 1223: 1221: 1220: 1215: 1210: 1209: 1208: 1198: 1193: 1187: 1185: 1179: 1178: 1176: 1175: 1170: 1165: 1164: 1163: 1153: 1148: 1142: 1140: 1131: 1125: 1124: 1122: 1121: 1116: 1111: 1106: 1101: 1096: 1091: 1086: 1081: 1076: 1071: 1066: 1065: 1064: 1059: 1054: 1049: 1044: 1039: 1028: 1026: 1018: 1017: 1014: 1007: 1006: 1001: 999: 998: 991: 984: 976: 969: 968: 950: 943: 914: 895: 893: 890: 889: 888: 885:Exact category 882: 875: 872: 854: 851: 829: 826: 802: 801: 790: 787: 783: 780: 776: 773: 770: 766: 763: 759: 756: 658:is said to be 650:A subcategory 647: 644: 570:full embedding 492: 489: 488: 487: 461: 442: 431: 424: 411: 408: 376: 375: 364: 361: 358: 355: 352: 349: 343: 337: 334: 331: 326: 323: 320: 317: 314: 311: 305: 299: 296: 293: 256:. We say that 205: 204: 177: 146: 136: 121: 120: 115:, denoted hom( 109: 78: 75: 45:is a category 15: 13: 10: 9: 6: 4: 3: 2: 1658: 1647: 1644: 1642: 1639: 1638: 1636: 1621: 1613: 1611: 1603: 1601: 1593: 1592: 1589: 1575: 1572: 1570: 1567: 1565: 1561: 1557: 1553: 1551: 1549: 1542: 1540: 1537: 1535: 1532: 1531: 1529: 1526: 1522: 1512: 1509: 1506: 1502: 1499: 1498: 1496: 1494: 1486: 1480: 1477: 1475: 1472: 1470: 1467: 1465: 1464:Tetracategory 1462: 1460: 1457: 1454: 1453:pseudofunctor 1450: 1447: 1446: 1444: 1442: 1434: 1431: 1427: 1422: 1419: 1417: 1414: 1412: 1409: 1407: 1404: 1402: 1399: 1397: 1394: 1392: 1389: 1387: 1384: 1382: 1378: 1372: 1371: 1368: 1364: 1359: 1355: 1350: 1332: 1329: 1327: 1324: 1322: 1319: 1317: 1314: 1312: 1309: 1307: 1304: 1302: 1299: 1297: 1296:Free category 1294: 1293: 1291: 1287: 1280: 1279:Vector spaces 1276: 1273: 1270: 1266: 1263: 1261: 1258: 1256: 1253: 1251: 1248: 1246: 1243: 1241: 1238: 1237: 1235: 1233: 1229: 1219: 1216: 1214: 1211: 1207: 1204: 1203: 1202: 1199: 1197: 1194: 1192: 1189: 1188: 1186: 1184: 1180: 1174: 1173:Inverse limit 1171: 1169: 1166: 1162: 1159: 1158: 1157: 1154: 1152: 1149: 1147: 1144: 1143: 1141: 1139: 1135: 1132: 1130: 1126: 1120: 1117: 1115: 1112: 1110: 1107: 1105: 1102: 1100: 1099:Kan extension 1097: 1095: 1092: 1090: 1087: 1085: 1082: 1080: 1077: 1075: 1072: 1070: 1067: 1063: 1060: 1058: 1055: 1053: 1050: 1048: 1045: 1043: 1040: 1038: 1035: 1034: 1033: 1030: 1029: 1027: 1023: 1019: 1012: 1008: 1004: 997: 992: 990: 985: 983: 978: 977: 974: 966: 964: 959: 954: 951: 946: 940: 936: 932: 928: 924: 918: 915: 907: 900: 897: 891: 886: 883: 881: 878: 877: 873: 871: 869: 852: 849: 827: 824: 815: 811: 807: 788: 781: 778: 771: 764: 761: 754: 747: 746: 745: 744: 740: 737: 733: 729: 724: 722: 718: 714: 710: 706: 701: 699: 698:strictly full 695: 691: 687: 683: 679: 675: 671: 667: 663: 662: 657: 653: 645: 643: 641: 636: 634: 630: 626: 622: 618: 614: 610: 606: 602: 598: 594: 590: 586: 582: 578: 573: 571: 567: 563: 559: 554: 552: 547: 545: 541: 537: 533: 528: 526: 522: 518: 514: 510: 506: 502: 498: 490: 485: 481: 477: 476:vector spaces 473: 469: 466: 462: 459: 455: 451: 447: 443: 440: 436: 432: 429: 425: 422: 418: 414: 413: 409: 407: 405: 401: 397: 393: 389: 385: 382:morphisms in 381: 362: 356: 353: 350: 324: 318: 315: 312: 282: 281: 280: 278: 274: 270: 266: 263: 259: 255: 251: 246: 244: 241:, called the 240: 236: 232: 229: 226: 222: 218: 214: 210: 202: 198: 194: 190: 186: 182: 178: 175: 171: 167: 163: 159: 155: 151: 147: 144: 139: 134: 130: 126: 125: 124: 118: 114: 110: 107: 104:, denoted ob( 103: 99: 98: 97: 95: 91: 88: 84: 76: 74: 72: 68: 64: 60: 56: 52: 48: 44: 41: 37: 33: 29: 22: 1544: 1525:Categorified 1429:n-categories 1380:Key concepts 1330: 1218:Direct limit 1201:Coequalizers 1119:Yoneda lemma 1025:Key concepts 1015:Key concepts 962: 953: 926: 923:Freyd, Peter 917: 899: 813: 809: 805: 803: 738: 731: 727: 725: 720: 712: 708: 704: 702: 697: 693: 689: 685: 681: 677: 673: 669: 665: 659: 655: 651: 649: 637: 632: 624: 620: 616: 612: 604: 600: 596: 592: 584: 580: 576: 574: 569: 565: 561: 557: 555: 550: 548: 531: 529: 524: 512: 508: 504: 500: 496: 494: 479: 471: 467: 452:-preserving 403: 399: 395: 391: 387: 383: 379: 377: 276: 272: 268: 264: 261: 257: 253: 249: 247: 242: 238: 234: 230: 220: 216: 212: 208: 206: 200: 196: 192: 188: 184: 180: 173: 169: 165: 161: 157: 153: 149: 142: 137: 132: 128: 122: 116: 112: 105: 101: 96:is given by 93: 89: 86: 82: 80: 70: 66: 62: 54: 46: 42: 35: 25: 1493:-categories 1469:Kan complex 1459:Tricategory 1441:-categories 1331:Subcategory 1089:Exponential 1057:Preadditive 1052:Pre-abelian 812:belongs to 717:Peter Freyd 607:induces an 540:isomorphism 417:finite sets 87:subcategory 36:subcategory 28:mathematics 1635:Categories 1511:3-category 1501:2-category 1474:∞-groupoid 1449:Bicategory 1196:Coproducts 1156:Equalizers 1062:Bicategory 892:References 684:such that 640:embeddings 629:equivalent 491:Embeddings 428:bijections 199:is in hom( 172:are in ob( 141:is in hom( 127:for every 123:such that 57:and whose 1646:Hierarchy 1560:Symmetric 1505:2-functor 1245:Relations 1168:Pullbacks 786:→ 775:→ 769:→ 758:→ 558:embedding 551:embedding 532:embedding 517:injective 59:morphisms 1620:Glossary 1600:Category 1574:n-monoid 1527:concepts 1183:Colimits 1151:Products 1104:Morphism 1047:Concrete 1042:Additive 1032:Category 874:See also 853:″ 828:′ 782:″ 765:′ 672: : 611:between 579: : 534:to be a 507: : 410:Examples 233: : 225:faithful 152: : 40:category 1610:Outline 1569:n-group 1534:2-group 1489:Strict 1479:∞-topos 1275:Modules 1213:Pushout 1161:Kernels 1094:Functor 1037:Abelian 960:at the 666:replete 484:modules 228:functor 187:in hom( 160:in hom( 51:objects 1556:Traced 1539:2-ring 1269:Fields 1255:Groups 1250:Magmas 1138:Limits 941:  734:of an 688:is in 603:, and 463:For a 131:in ob( 49:whose 1550:-ring 1437:Weak 1421:Topos 1265:Rings 909:(PDF) 841:and 619:. If 589:image 465:field 446:rings 260:is a 38:of a 1240:Sets 939:ISBN 713:lluf 709:wide 615:and 587:the 521:full 458:rngs 450:unit 433:The 271:and 248:Let 183:and 81:Let 34:, a 1084:End 1074:CCC 965:Lab 931:doi 804:in 711:or 707:is 680:in 664:or 654:of 631:to 627:is 599:of 591:of 499:of 394:in 380:all 275:of 92:of 26:In 1637:: 1562:) 1558:)( 937:. 870:. 808:, 726:A 700:. 676:→ 642:. 635:. 583:→ 511:→ 406:. 279:, 237:→ 195:o 176:), 156:→ 145:), 119:). 108:), 1554:( 1547:n 1545:E 1507:) 1503:( 1491:n 1455:) 1451:( 1439:n 1281:) 1277:( 1271:) 1267:( 995:e 988:t 981:v 963:n 947:. 933:: 911:. 850:M 825:M 814:S 810:M 806:C 789:0 779:M 772:M 762:M 755:0 739:C 732:S 721:C 705:C 694:S 690:S 686:Y 682:C 678:Y 674:X 670:k 656:C 652:S 633:B 625:F 621:F 617:S 613:B 605:F 601:C 597:S 593:F 585:C 581:B 577:F 566:F 562:F 525:S 513:C 509:S 505:I 501:C 497:S 486:. 482:- 480:K 474:- 472:K 468:K 460:. 441:. 423:. 404:A 400:C 396:C 392:A 388:S 384:C 363:. 360:) 357:Y 354:, 351:X 348:( 342:C 336:m 333:o 330:H 325:= 322:) 319:Y 316:, 313:X 310:( 304:S 298:m 295:o 292:H 277:S 273:Y 269:X 265:C 258:S 254:C 250:S 239:C 235:S 231:I 221:C 217:S 213:S 209:S 201:S 197:g 193:f 189:S 185:g 181:f 174:S 170:Y 166:X 162:S 158:Y 154:X 150:f 143:S 138:X 133:S 129:X 117:S 113:C 106:S 102:C 94:C 90:S 83:C 71:C 67:C 63:C 55:C 47:S 43:C 23:.

Index

Knowledge (XXG):Subcategories
mathematics
category theory
category
objects
morphisms
faithful
functor
finite sets
category of sets
bijections
category of abelian groups
category of groups
rings
unit
ring homomorphisms
rngs
field
vector spaces
modules
injective
full
full and faithful functor
isomorphism
Yoneda embedding
image
isomorphism of categories
equivalent
embeddings
isomorphism-closed

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