Knowledge

Injective object

Source đź“ť

25: 1197: 130: 1109: 568: 723: 448: 2081: 2047: 2002: 1952: 1918: 1888: 1855: 1825: 1789: 1736: 1707: 1677: 1624: 1569: 1478: 1387: 1290: 1763: 1652: 1598: 1361: 1316: 1266: 850: 817: 787: 749: 654: 628: 590: 215: 1542: 393: 1510: 1454: 1422: 321: 289: 254: 422: 1339: 511: 491: 471: 361: 341: 190: 2142:
Jiri Adamek, Horst Herrlich, George Strecker. Abstract and concrete categories: The joy of cats, Chapter 9, Injective Objects and Essential Embeddings,
54: 1043: 1126:
to this sequence and computing the homology of the resulting (not necessarily exact) sequence. This approach is used to define
526: 517: 1236: 2055: 76: 47: 2128:. Reprints in Theory and Applications of Categories, No. 17 (2006) pp. 1-507. orig. John Wiley. pp. 147–155. 2119:
Adamek, Jiri; Herrlich, Horst; Strecker, George (1990). "Sec. 9. Injective objects and essential embeddings".
684: 427: 974: 37: 2062: 2028: 1983: 1933: 1899: 1869: 1836: 1806: 1770: 1717: 1688: 1658: 1605: 1550: 1459: 1368: 1271: 2169: 170: 41: 33: 1746: 1635: 1581: 1344: 1299: 1249: 833: 800: 770: 732: 637: 611: 573: 198: 1515: 366: 982: 853: 193: 58: 1483: 1427: 1395: 294: 262: 227: 2013: 1185: 401: 1030: 931: 2143: 2120: 8: 935: 1324: 1293: 1147: 1143: 1009: 1001: 916: 496: 476: 456: 346: 326: 175: 129: 2094: 118: 2021: 1155: 1151: 947: 605: 102: 2051: 1115: 1017: 924: 756: 110: 94: 2144:
Republished in Reprints and Applications of Categories, No. 17 (2006) pp. 1-507
1976: 1005: 959: 726: 657: 114: 2163: 912: 675: 2017: 1572: 1168: 1139: 222: 2006: 1131: 1127: 1013: 661: 521: 90: 1135: 986: 593: 106: 473:
in the above definition is not required to be uniquely determined by
1196: 993: 257: 608:, and this is still one of its primary areas of application. When 1575:, we are back to the injective objects that were treated above. 899: 1104:{\displaystyle 0\to X\to Q^{0}\to Q^{1}\to Q^{2}\to \cdots } 927:. Assuming the axiom of choice, the notions are equivalent. 1029:
If an abelian category has enough injectives, we can form
762: 563:{\displaystyle \operatorname {Hom} _{\mathbf {C} }(-,Q)} 2118: 2065: 2031: 1986: 1936: 1902: 1872: 1839: 1809: 1773: 1749: 1720: 1691: 1661: 1638: 1608: 1584: 1553: 1518: 1486: 1462: 1430: 1398: 1371: 1347: 1327: 1302: 1274: 1252: 1046: 895:. The injective hull is then uniquely determined by 836: 803: 773: 735: 687: 640: 614: 576: 529: 499: 479: 459: 430: 404: 369: 349: 329: 297: 265: 230: 201: 178: 604:The notion of injectivity was first formulated for 2075: 2041: 1996: 1979:, the injective objects with respect to the class 1963: 1946: 1912: 1882: 1849: 1819: 1783: 1757: 1730: 1701: 1671: 1646: 1618: 1592: 1563: 1536: 1504: 1472: 1448: 1416: 1381: 1355: 1333: 1310: 1284: 1260: 1103: 985:, and the injective hull of a metric space is its 844: 811: 781: 743: 717: 648: 622: 584: 562: 505: 485: 465: 442: 416: 387: 355: 335: 315: 283: 248: 209: 184: 2149:J. Rosicky, Injectivity and accessible categories 2122:Abstract and Concrete Categories: The Joy of Cats 2161: 46:but its sources remain unclear because it lacks 2156:-reflection and injective hulls of fibre spaces 520:category, it is equivalent to require that the 1150:. The categories being used are typically 2024:form the injective objects for the class 875:is an essential monomorphism with domain 77:Learn how and when to remove this message 1195: 599: 128: 923:, an injective object is necessarily a 2162: 137:is injective if, given a monomorphism 101:is a generalization of the concept of 16:Mathematical object in category theory 763:Enough injectives and injective hulls 718:{\displaystyle 0\to Q\to U\to V\to 0} 2114: 2112: 2110: 18: 819:, there exists a monomorphism from 424:factors through every monomorphism 13: 2068: 2058:of a partially ordered set is its 2034: 1989: 1939: 1905: 1875: 1842: 1812: 1776: 1723: 1694: 1664: 1611: 1556: 1465: 1374: 1277: 1037:we can form a long exact sequence 1004:, an injective object is always a 630:is an abelian category, an object 443:{\displaystyle X\hookrightarrow Y} 14: 2181: 2107: 1191: 1891:-essential morphism with domain 1751: 1640: 1586: 1349: 1304: 1254: 838: 805: 775: 737: 642: 616: 578: 536: 203: 23: 2152:F. Cagliari and S. Montovani, T 117:. The dual notion is that of a 105:. This concept is important in 2076:{\displaystyle {\mathcal {H}}} 2042:{\displaystyle {\mathcal {H}}} 1997:{\displaystyle {\mathcal {H}}} 1947:{\displaystyle {\mathcal {H}}} 1913:{\displaystyle {\mathcal {H}}} 1883:{\displaystyle {\mathcal {H}}} 1850:{\displaystyle {\mathcal {H}}} 1820:{\displaystyle {\mathcal {H}}} 1784:{\displaystyle {\mathcal {H}}} 1731:{\displaystyle {\mathcal {H}}} 1702:{\displaystyle {\mathcal {H}}} 1672:{\displaystyle {\mathcal {H}}} 1619:{\displaystyle {\mathcal {H}}} 1564:{\displaystyle {\mathcal {H}}} 1496: 1473:{\displaystyle {\mathcal {H}}} 1440: 1408: 1382:{\displaystyle {\mathcal {H}}} 1285:{\displaystyle {\mathcal {H}}} 1134:functors and also the various 1095: 1082: 1069: 1056: 1050: 709: 703: 697: 691: 557: 545: 434: 408: 307: 275: 240: 1: 2136: 2056:Dedekind–MacNeille completion 1012:, and therefore it is always 902:a non-canonical isomorphism. 124: 93:, especially in the field of 1758:{\displaystyle \mathbf {C} } 1647:{\displaystyle \mathbf {C} } 1593:{\displaystyle \mathbf {C} } 1356:{\displaystyle \mathbf {C} } 1311:{\displaystyle \mathbf {C} } 1261:{\displaystyle \mathbf {C} } 1114:and one can then define the 981:, an injective object is an 946:, an injective object is an 845:{\displaystyle \mathbf {C} } 812:{\displaystyle \mathbf {C} } 782:{\displaystyle \mathbf {C} } 744:{\displaystyle \mathbf {C} } 649:{\displaystyle \mathbf {C} } 623:{\displaystyle \mathbf {C} } 585:{\displaystyle \mathbf {C} } 210:{\displaystyle \mathbf {C} } 7: 2088: 905: 10: 2186: 2005:of anodyne extensions are 1537:{\displaystyle g\circ h=f} 1184:) or, more generally, any 1033:, i.e. for a given object 930:In the category of (left) 879:and an injective codomain 864:is a monomorphism only if 388:{\displaystyle h\circ f=g} 975:category of metric spaces 823:to an injective object. 570:carries monomorphisms in 2100: 1505:{\displaystyle g:B\to Q} 1480:there exists a morphism 1449:{\displaystyle h:A\to B} 1417:{\displaystyle f:A\to Q} 398:That is, every morphism 316:{\displaystyle h:Y\to Q} 291:there exists a morphism 284:{\displaystyle g:X\to Q} 249:{\displaystyle f:X\to Y} 32:This article includes a 1024: 970:has enough injectives). 755:is injective, then the 61:more precise citations. 2077: 2043: 2014:partially ordered sets 1998: 1948: 1914: 1884: 1851: 1821: 1785: 1759: 1732: 1703: 1673: 1648: 1620: 1594: 1565: 1538: 1506: 1474: 1450: 1418: 1392:if for every morphism 1383: 1357: 1335: 1312: 1286: 1268:be a category and let 1262: 1243: 1105: 983:injective metric space 854:essential monomorphism 846: 813: 791:have enough injectives 783: 745: 719: 650: 624: 586: 564: 507: 487: 467: 444: 418: 417:{\displaystyle X\to Q} 389: 357: 337: 317: 285: 250: 211: 186: 166: 2078: 2044: 1999: 1949: 1915: 1885: 1852: 1822: 1786: 1760: 1733: 1704: 1674: 1649: 1621: 1595: 1566: 1539: 1507: 1475: 1451: 1419: 1384: 1358: 1336: 1313: 1287: 1263: 1208:-injective if, given 1199: 1186:Grothendieck category 1106: 1031:injective resolutions 847: 814: 784: 746: 720: 651: 625: 600:In Abelian categories 587: 565: 508: 488: 468: 445: 419: 390: 358: 338: 318: 286: 251: 212: 187: 132: 113:and in the theory of 2063: 2029: 1984: 1934: 1921:-injective codomain 1900: 1870: 1837: 1807: 1794:if for any morphism 1771: 1747: 1718: 1689: 1659: 1636: 1628:if for every object 1606: 1582: 1551: 1516: 1484: 1460: 1428: 1396: 1369: 1345: 1325: 1300: 1272: 1250: 1044: 936:module homomorphisms 856:if for any morphism 834: 801: 793:if for every object 771: 733: 685: 638: 612: 574: 527: 497: 477: 457: 428: 402: 367: 347: 327: 295: 263: 228: 199: 176: 2012:In the category of 1975:In the category of 1710:-injective object. 1424:and every morphism 1118:of a given functor 1002:continuous mappings 992:In the category of 962:(as a consequence, 917:group homomorphisms 911:In the category of 868:is a monomorphism. 161:can be extended to 2073: 2039: 1994: 1970:-injective objects 1944: 1910: 1880: 1847: 1817: 1781: 1755: 1728: 1699: 1669: 1654:, there exists an 1644: 1616: 1590: 1561: 1534: 1502: 1470: 1446: 1414: 1379: 1353: 1331: 1308: 1282: 1258: 1244: 1152:functor categories 1148:algebraic geometry 1144:algebraic topology 1101: 1010:continuous lattice 842: 809: 779: 741: 715: 646: 620: 606:abelian categories 582: 560: 503: 483: 463: 440: 414: 385: 353: 333: 313: 281: 246: 207: 182: 167: 34:list of references 2095:Projective object 2022:complete lattices 1334:{\displaystyle Q} 1154:or categories of 506:{\displaystyle g} 486:{\displaystyle f} 466:{\displaystyle h} 363:, i.e. such that 356:{\displaystyle Y} 336:{\displaystyle g} 185:{\displaystyle Q} 119:projective object 97:, the concept of 87: 86: 79: 2177: 2130: 2129: 2127: 2116: 2084:-injective hull. 2082: 2080: 2079: 2074: 2072: 2071: 2052:order-embeddings 2048: 2046: 2045: 2040: 2038: 2037: 2003: 2001: 2000: 1995: 1993: 1992: 1969: 1968: 1953: 1951: 1950: 1945: 1943: 1942: 1919: 1917: 1916: 1911: 1909: 1908: 1889: 1887: 1886: 1881: 1879: 1878: 1856: 1854: 1853: 1848: 1846: 1845: 1826: 1824: 1823: 1818: 1816: 1815: 1798:, the composite 1790: 1788: 1787: 1782: 1780: 1779: 1764: 1762: 1761: 1756: 1754: 1737: 1735: 1734: 1729: 1727: 1726: 1708: 1706: 1705: 1700: 1698: 1697: 1678: 1676: 1675: 1670: 1668: 1667: 1653: 1651: 1650: 1645: 1643: 1625: 1623: 1622: 1617: 1615: 1614: 1599: 1597: 1596: 1591: 1589: 1571:is the class of 1570: 1568: 1567: 1562: 1560: 1559: 1543: 1541: 1540: 1535: 1511: 1509: 1508: 1503: 1479: 1477: 1476: 1471: 1469: 1468: 1455: 1453: 1452: 1447: 1423: 1421: 1420: 1415: 1388: 1386: 1385: 1380: 1378: 1377: 1362: 1360: 1359: 1354: 1352: 1340: 1338: 1337: 1332: 1317: 1315: 1314: 1309: 1307: 1296:of morphisms of 1291: 1289: 1288: 1283: 1281: 1280: 1267: 1265: 1264: 1259: 1257: 1116:derived functors 1110: 1108: 1107: 1102: 1094: 1093: 1081: 1080: 1068: 1067: 948:injective module 860:, the composite 851: 849: 848: 843: 841: 818: 816: 815: 810: 808: 788: 786: 785: 780: 778: 750: 748: 747: 742: 740: 724: 722: 721: 716: 655: 653: 652: 647: 645: 629: 627: 626: 621: 619: 591: 589: 588: 583: 581: 569: 567: 566: 561: 541: 540: 539: 512: 510: 509: 504: 492: 490: 489: 484: 472: 470: 469: 464: 449: 447: 446: 441: 423: 421: 420: 415: 394: 392: 391: 386: 362: 360: 359: 354: 342: 340: 339: 334: 322: 320: 319: 314: 290: 288: 287: 282: 255: 253: 252: 247: 216: 214: 213: 208: 206: 191: 189: 188: 183: 115:model categories 103:injective module 99:injective object 82: 75: 71: 68: 62: 57:this article by 48:inline citations 27: 26: 19: 2185: 2184: 2180: 2179: 2178: 2176: 2175: 2174: 2170:Category theory 2160: 2159: 2155: 2146:, Wiley (1990). 2139: 2134: 2133: 2125: 2117: 2108: 2103: 2091: 2067: 2066: 2064: 2061: 2060: 2033: 2032: 2030: 2027: 2026: 1988: 1987: 1985: 1982: 1981: 1977:simplicial sets 1972: 1966: 1965: 1954:-injective hull 1938: 1937: 1935: 1932: 1931: 1904: 1903: 1901: 1898: 1897: 1874: 1873: 1871: 1868: 1867: 1841: 1840: 1838: 1835: 1834: 1811: 1810: 1808: 1805: 1804: 1775: 1774: 1772: 1769: 1768: 1750: 1748: 1745: 1744: 1722: 1721: 1719: 1716: 1715: 1693: 1692: 1690: 1687: 1686: 1680:-morphism from 1663: 1662: 1660: 1657: 1656: 1639: 1637: 1634: 1633: 1610: 1609: 1607: 1604: 1603: 1585: 1583: 1580: 1579: 1555: 1554: 1552: 1549: 1548: 1517: 1514: 1513: 1485: 1482: 1481: 1464: 1463: 1461: 1458: 1457: 1429: 1426: 1425: 1397: 1394: 1393: 1373: 1372: 1370: 1367: 1366: 1348: 1346: 1343: 1342: 1326: 1323: 1322: 1303: 1301: 1298: 1297: 1276: 1275: 1273: 1270: 1269: 1253: 1251: 1248: 1247: 1241: 1237:factors through 1235: 1231: 1227: 1223: 1219: 1215: 1211: 1207: 1203: 1194: 1183: 1164: 1089: 1085: 1076: 1072: 1063: 1059: 1045: 1042: 1041: 1027: 1018:locally compact 997: 960:injective hulls 925:divisible group 908: 837: 835: 832: 831: 826:A monomorphism 804: 802: 799: 798: 774: 772: 769: 768: 765: 757:sequence splits 736: 734: 731: 730: 686: 683: 682: 669: 641: 639: 636: 635: 615: 613: 610: 609: 602: 577: 575: 572: 571: 535: 534: 530: 528: 525: 524: 498: 495: 494: 478: 475: 474: 458: 455: 454: 429: 426: 425: 403: 400: 399: 368: 365: 364: 348: 345: 344: 328: 325: 324: 296: 293: 292: 264: 261: 260: 229: 226: 225: 202: 200: 197: 196: 177: 174: 173: 164: 160: 156: 152: 148: 144: 140: 136: 127: 111:homotopy theory 95:category theory 83: 72: 66: 63: 52: 38:related reading 28: 24: 17: 12: 11: 5: 2183: 2173: 2172: 2158: 2157: 2153: 2150: 2147: 2138: 2135: 2132: 2131: 2105: 2104: 2102: 2099: 2098: 2097: 2090: 2087: 2086: 2085: 2070: 2036: 2010: 1991: 1971: 1962: 1941: 1907: 1877: 1844: 1814: 1778: 1753: 1725: 1696: 1666: 1642: 1613: 1588: 1558: 1533: 1530: 1527: 1524: 1521: 1501: 1498: 1495: 1492: 1489: 1467: 1445: 1442: 1439: 1436: 1433: 1413: 1410: 1407: 1404: 1401: 1376: 1363:is said to be 1351: 1330: 1306: 1279: 1256: 1239: 1233: 1229: 1225: 1221: 1217: 1213: 1209: 1205: 1201: 1193: 1192:Generalization 1190: 1179: 1160: 1112: 1111: 1100: 1097: 1092: 1088: 1084: 1079: 1075: 1071: 1066: 1062: 1058: 1055: 1052: 1049: 1026: 1023: 1022: 1021: 1006:Scott topology 995: 990: 971: 928: 913:abelian groups 907: 904: 889:injective hull 840: 807: 777: 764: 761: 739: 727:exact sequence 714: 711: 708: 705: 702: 699: 696: 693: 690: 665: 658:if and only if 644: 618: 601: 598: 580: 559: 556: 553: 550: 547: 544: 538: 533: 502: 482: 462: 439: 436: 433: 413: 410: 407: 384: 381: 378: 375: 372: 352: 332: 312: 309: 306: 303: 300: 280: 277: 274: 271: 268: 245: 242: 239: 236: 233: 217:is said to be 205: 181: 162: 158: 154: 150: 146: 142: 138: 134: 126: 123: 85: 84: 42:external links 31: 29: 22: 15: 9: 6: 4: 3: 2: 2182: 2171: 2168: 2167: 2165: 2151: 2148: 2145: 2141: 2140: 2124: 2123: 2115: 2113: 2111: 2106: 2096: 2093: 2092: 2083: 2057: 2053: 2049: 2023: 2019: 2018:monotone maps 2015: 2011: 2008: 2007:Kan complexes 2004: 1978: 1974: 1973: 1961: 1959: 1955: 1929:is called an 1928: 1924: 1920: 1894: 1890: 1864: 1859: 1857: 1831: 1827: 1801: 1797: 1793: 1791: 1742: 1738: 1711: 1709: 1683: 1679: 1631: 1627: 1578:The category 1576: 1574: 1573:monomorphisms 1545: 1531: 1528: 1525: 1522: 1519: 1499: 1493: 1490: 1487: 1443: 1437: 1434: 1431: 1411: 1405: 1402: 1399: 1391: 1389: 1328: 1319: 1295: 1238: 1198: 1189: 1187: 1182: 1178: 1174: 1170: 1166: 1163: 1159: 1153: 1149: 1145: 1141: 1137: 1133: 1129: 1125: 1121: 1117: 1098: 1090: 1086: 1077: 1073: 1064: 1060: 1053: 1047: 1040: 1039: 1038: 1036: 1032: 1019: 1015: 1011: 1007: 1003: 999: 991: 988: 984: 980: 976: 972: 969: 965: 961: 957: 953: 949: 945: 941: 937: 933: 929: 926: 922: 918: 914: 910: 909: 903: 901: 898: 894: 890: 887:is called an 886: 882: 878: 874: 869: 867: 863: 859: 855: 852:is called an 829: 824: 822: 796: 792: 767:The category 760: 758: 754: 728: 712: 706: 700: 694: 688: 679: 677: 673: 668: 663: 659: 656:is injective 633: 607: 597: 595: 554: 551: 548: 542: 531: 523: 519: 518:locally small 514: 500: 480: 460: 453:The morphism 451: 437: 431: 411: 405: 396: 382: 379: 376: 373: 370: 350: 330: 310: 304: 301: 298: 278: 272: 269: 266: 259: 243: 237: 234: 231: 224: 221:if for every 220: 195: 179: 172: 131: 122: 120: 116: 112: 108: 104: 100: 96: 92: 81: 78: 70: 60: 56: 50: 49: 43: 39: 35: 30: 21: 20: 2121: 2059: 2025: 1980: 1964:Examples of 1957: 1930: 1926: 1922: 1896: 1892: 1866: 1862: 1860: 1833: 1829: 1803: 1799: 1795: 1767: 1766: 1740: 1714: 1712: 1685: 1681: 1655: 1629: 1602:have enough 1601: 1577: 1546: 1365: 1364: 1320: 1245: 1180: 1176: 1172: 1169:ringed space 1161: 1157: 1140:group theory 1138:theories in 1123: 1122:by applying 1119: 1113: 1034: 1028: 978: 967: 963: 955: 951: 943: 939: 920: 896: 892: 888: 884: 880: 876: 872: 870: 865: 861: 857: 827: 825: 820: 794: 790: 766: 752: 680: 671: 666: 631: 603: 515: 452: 397: 223:monomorphism 218: 168: 98: 88: 73: 67:October 2021 64: 53:Please help 45: 1626:-injectives 1600:is said to 1156:sheaves of 789:is said to 662:hom functor 522:hom functor 91:mathematics 59:introducing 2137:References 2054:, and the 1792:-essential 1765:is called 1739:-morphism 1390:-injective 1321:An object 1200:An object 1167:over some 1136:cohomology 987:tight span 751:such that 596:set maps. 594:surjective 323:extending 256:and every 133:An object 125:Definition 107:cohomology 1523:∘ 1497:→ 1441:→ 1409:→ 1099:⋯ 1096:→ 1083:→ 1070:→ 1057:→ 1051:→ 710:→ 704:→ 698:→ 692:→ 670:(–, 549:− 543:⁡ 435:↪ 409:→ 374:∘ 308:→ 276:→ 241:→ 219:injective 2164:Category 2089:See also 1828:only if 1228: : 1212: : 906:Examples 258:morphism 194:category 153: : 141: : 1925:, then 1895:and an 1165:modules 973:In the 932:modules 883:, then 55:improve 2020:, the 1832:is in 1802:is in 1684:to an 1224:, any 1130:, and 998:spaces 725:is an 171:object 149:, any 2126:(PDF) 2101:Notes 1865:is a 1512:with 1294:class 1292:be a 1014:sober 1008:on a 900:up to 676:exact 674:) is 516:In a 192:in a 109:, in 40:, or 2016:and 1246:Let 1146:and 1025:Uses 1016:and 1000:and 958:has 934:and 915:and 660:its 493:and 2050:of 1960:. 1956:of 1861:If 1743:in 1632:of 1547:If 1456:in 1341:of 1220:in 1204:is 1132:Tor 1128:Ext 979:Met 968:Mod 956:Mod 944:Mod 891:of 871:If 830:in 797:of 729:in 681:If 664:Hom 634:of 592:to 532:Hom 343:to 169:An 89:In 2166:: 2109:^ 1858:. 1800:fg 1713:A 1544:. 1318:. 1232:→ 1216:→ 1188:. 1175:, 1142:, 977:, 950:. 938:, 921:Ab 919:, 862:fg 759:. 678:. 513:. 450:. 395:. 157:→ 145:→ 121:. 44:, 36:, 2154:0 2069:H 2035:H 2009:. 1990:H 1967:H 1958:X 1940:H 1927:G 1923:G 1906:H 1893:X 1876:H 1863:g 1843:H 1830:f 1813:H 1796:f 1777:H 1752:C 1741:g 1724:H 1695:H 1682:X 1665:H 1641:C 1630:X 1612:H 1587:C 1557:H 1532:f 1529:= 1526:h 1520:g 1500:Q 1494:B 1491:: 1488:g 1466:H 1444:B 1438:A 1435:: 1432:h 1412:Q 1406:A 1403:: 1400:f 1375:H 1350:C 1329:Q 1305:C 1278:H 1255:C 1242:. 1240:h 1234:Q 1230:A 1226:f 1222:H 1218:B 1214:A 1210:h 1206:H 1202:Q 1181:X 1177:O 1173:X 1171:( 1162:X 1158:O 1124:F 1120:F 1091:2 1087:Q 1078:1 1074:Q 1065:0 1061:Q 1054:X 1048:0 1035:X 1020:. 996:0 994:T 989:. 966:- 964:R 954:- 952:R 942:- 940:R 897:X 893:X 885:G 881:G 877:X 873:g 866:f 858:f 839:C 828:g 821:X 806:C 795:X 776:C 753:Q 738:C 713:0 707:V 701:U 695:Q 689:0 672:Q 667:C 643:C 632:Q 617:C 579:C 558:) 555:Q 552:, 546:( 537:C 501:g 481:f 461:h 438:Y 432:X 412:Q 406:X 383:g 380:= 377:f 371:h 351:Y 331:g 311:Q 305:Y 302:: 299:h 279:Q 273:X 270:: 267:g 244:Y 238:X 235:: 232:f 204:C 180:Q 165:. 163:Y 159:Q 155:X 151:g 147:Y 143:X 139:f 135:Q 80:) 74:( 69:) 65:( 51:.

Index

list of references
related reading
external links
inline citations
improve
introducing
Learn how and when to remove this message
mathematics
category theory
injective module
cohomology
homotopy theory
model categories
projective object

object
category
monomorphism
morphism
locally small
hom functor
surjective
abelian categories
if and only if
hom functor
exact
exact sequence
sequence splits
essential monomorphism
up to

Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.

↑