Knowledge (XXG)

Exact functor

Source πŸ“

4277: 4086: 3247: 2711: 2285: 3476: 3712: 327: 3888: 2868: 1887: 4406:
Despite its abstraction, this general definition has useful consequences. For example, in section 1.8, Grothendieck proves that a functor is pro-representable if and only if it is left exact, under some mild conditions on the category
4065: 2413: 186: 3962: 2159: 4272:{\displaystyle :\mathbf {Z} /12\mathbf {Z} \otimes _{Z}P\cong (\mathbf {Z} \otimes _{Z}P)/(12\mathbf {Z} \otimes _{Z}P)=(\mathbf {Z} \otimes _{Z}P)/(3\mathbf {Z} \otimes _{Z}P)\cong \mathbf {Z} P/3\mathbf {Z} P} 2576: 1804: 1527: 46:. Exact functors are convenient for algebraic calculations because they can be directly applied to presentations of objects. Much of the work in homological algebra is designed to cope with functors that 3057: 4383: 2593: 2175: 3340: 3541: 205: 2501: 3717: 2918: 1979: 1944: 2972: 3019: 4319: 3332: 3290: 4340:
into colimits; a contravariant functor is left exact iff it turns finite colimits into limits; a contravariant functor is right exact iff it turns finite limits into colimits.
2720: 3052: 1838: 1909: 1833: 1762: 1559: 1453: 1419: 1397: 1375: 1353: 1661: 1631: 3517: 1485: 1690: 3967: 1605: 2308: 1730: 1710: 1579: 4386:, tome I, section 1, the notion of left (right) exact functors are defined for general categories, and not just abelian ones. The definition is as follows: 109: 3893: 2088: 4493: 2509: 4525: 3242:{\displaystyle x_{i}\in R,\sum _{i}x_{i}(r_{i}\otimes p_{i})=\sum _{i}1\otimes (r_{i}x_{i}p_{i})=1\otimes (\sum _{i}r_{i}x_{i}p_{i})} 1767: 1490: 4576: 2706:{\displaystyle I\otimes _{R}P{\stackrel {f\otimes P}{\to }}R\otimes _{R}P{\stackrel {g\otimes P}{\to }}R/I\otimes _{R}P\to 0} 507: 2280:{\displaystyle A\otimes _{R}P{\stackrel {f\otimes P}{\to }}B\otimes _{R}P{\stackrel {g\otimes P}{\to }}C\otimes _{R}P\to 0} 3471:{\displaystyle P=\mathbf {Z} :=\{a/2^{k}:a,k\in \mathbf {Z} \},P\otimes \mathbf {Z} /m\mathbf {Z} \cong P/k\mathbf {Z} P} 4637: 4632: 3707:{\displaystyle (12z)\otimes (a/2^{k})\in (12\mathbf {Z} \otimes _{Z}P).(12z)\otimes (a/2^{k})=(3z)\otimes (a/2^{k-2})} 322:{\displaystyle 0\to F(A)\ {\stackrel {F(f)}{\longrightarrow }}\ F(B)\ {\stackrel {F(g)}{\longrightarrow }}\ F(C)\to 0} 3883:{\displaystyle (3z)\otimes (a/2^{k})\in (3\mathbf {Z} \otimes _{Z}P),(3z)\otimes (a/2^{k})=(12z)\otimes (a/2^{k+2})} 4591: 1030: 2442: 2884: 1135: 976: 1949: 1914: 19:
This article is about exact functors in homological algebra. For exact functors between regular categories, see
2927: 2977: 4333: 4282: 3295: 3256: 4518: 2863:{\displaystyle R/I\otimes _{R}P\cong (R\otimes _{R}P)/Image(f\otimes P)=(R\otimes _{R}P)/(I\otimes _{R}P)} 1996: 1607:. The given tensor products only have pure tensors. Therefore, it suffices to show that if a pure tensor 4606: 519: 719:β†’0 to have some exactness preserved. The following definitions are equivalent to the ones given above: 4279:. The last congruence follows by a similar argument to one in the proof of the corollary showing that 1882:{\displaystyle 5\mathbf {Z} \hookrightarrow \mathbf {Z} \twoheadrightarrow \mathbf {Z} /5\mathbf {Z} } 1813:
is not flat, then tensor product is not left exact. For example, consider the short exact sequence of
4556: 2162: 1220: 1162: 1154: 192: 43: 3024: 2875: 2428: 1233: 1177: 1097: 31: 4354:
Left and right exact functors are ubiquitous mainly because of the following fact: if the functor
1892: 1816: 1735: 1532: 1436: 1402: 1380: 1358: 1336: 2055:
While tensoring may not be left exact, it can be shown that tensoring is a right exact functor:
1208: 67: 1640: 1610: 3481: 4642: 4586: 4511: 4489: 1458: 1173: 1051: 85: 4601: 4571: 4566: 4551: 4546: 4422: 4359: 4332:
A covariant (not necessarily additive) functor is left exact if and only if it turns finite
4060:{\displaystyle P=\mathbf {Z} ,A=12\mathbf {Z} ,B=\mathbf {Z} ,C=\mathbf {Z} /12\mathbf {Z} } 2079: 2000: 1634: 1147: 1086: 88: 20: 4402:
is left (resp. right) exact if it commutes with finite projective (resp. inductive) limits.
2408:{\displaystyle f\otimes P(a\otimes p):=f(a)\otimes p,g\otimes P(b\otimes p):=g(b)\otimes p} 4596: 4561: 4481: 4348: 4344: 1666: 1584: 4611: 4415: 4347:; the degree to which a right exact functor fails to be exact can be measured with its 1993: 1715: 1695: 1564: 1245: 4425:
are sometimes called exact functors and generalize the exact functors discussed here.
4626: 1430: 1181: 4343:
The degree to which a left exact functor fails to be exact can be measured with its
4394:
be a category with finite projective (resp. injective) limits. Then a functor from
1273:. This is a covariant right exact functor; in other words, given an exact sequence 1105: 4079:
modules by the usual multiplication action and satisfy the conditions of the main
1330: 983: 27: 4336:
into limits; a covariant functor is right exact if and only if it turns finite
4083:. By the exactness implied by the theorem and by the above note we obtain that 181:{\displaystyle 0\to A\ {\stackrel {f}{\to }}\ B\ {\stackrel {g}{\to }}\ C\to 0} 3524: 3250: 1131: 2420: 3957:{\displaystyle (12\mathbf {Z} \otimes _{Z}P)=(3\mathbf {Z} \otimes _{Z}P)} 2154:{\displaystyle A\ {\stackrel {f}{\to }}\ B\ {\stackrel {g}{\to }}\ C\to 0} 707:
It is not always necessary to start with an entire short exact sequence 0β†’
4418:
generalize the exact functors between abelian categories discussed here.
4329:
A functor is exact if and only if it is both left exact and right exact.
1165:, and any additive functor turns split sequences into split sequences.) 4534: 4337: 4080: 3021:. So, the kernel of this map cannot contain any nonzero pure tensors. 39: 2571:{\displaystyle I{\stackrel {f}{\to }}R{\stackrel {g}{\to }}R/I\to 0} 1081:) is a contravariant left-exact functor; it is exact if and only if 1157:. Alternatively, one can argue that every short exact sequence of 4503: 336:. (The maps are often omitted and implied, and one says: "if 0β†’ 4507: 1799:{\displaystyle M\otimes \mathbb {Q} \to N\otimes \mathbb {Q} } 1522:{\displaystyle M\otimes \mathbb {Q} \to N\otimes \mathbb {Q} } 2302:-modules and not merely of abelian groups). Here, we define 1487:, then the corresponding map between the tensor products 982:
The most basic examples of left exact functors are the
50:
to be exact, but in ways that can still be controlled.
1188:. The covariant functor that associates to each sheaf 1134:). This yields a contravariant exact functor from the 4285: 4089: 3970: 3896: 3720: 3544: 3484: 3343: 3298: 3259: 3060: 3027: 2980: 2930: 2924:-linearly extending the map defined on pure tensors: 2887: 2723: 2596: 2512: 2445: 2311: 2178: 2091: 1952: 1917: 1895: 1841: 1819: 1770: 1738: 1718: 1698: 1669: 1643: 1613: 1587: 1567: 1535: 1493: 1461: 1439: 1405: 1383: 1361: 1339: 208: 112: 4313: 4271: 4059: 3956: 3882: 3706: 3511: 3470: 3326: 3284: 3241: 3046: 3013: 2966: 2912: 2862: 2705: 2570: 2495: 2407: 2279: 2153: 1973: 1938: 1903: 1881: 1827: 1798: 1756: 1724: 1704: 1684: 1655: 1625: 1599: 1573: 1553: 1521: 1479: 1447: 1413: 1391: 1369: 1347: 506:) is exact. This is distinct from the notion of a 321: 180: 1946:gives a sequence that is no longer exact, since 2298:is commutative, this sequence is a sequence of 1176:, we can consider the abelian category of all 1142:to itself. (Exactness follows from the above: 1025:) defines a covariant left-exact functor from 4519: 8: 3416: 3375: 2496:{\displaystyle P\otimes _{R}(R/I)\cong P/IP} 16:Functor that preserves short exact sequences 3249:. So, this map is injective. It is clearly 2913:{\displaystyle R\otimes _{R}P\rightarrow P} 2586:is the projection, is an exact sequence of 4526: 4512: 4504: 3337:As another application, we show that for, 1974:{\displaystyle \mathbf {Z} /5\mathbf {Z} } 1939:{\displaystyle \mathbf {Z} /5\mathbf {Z} } 4293: 4284: 4261: 4253: 4245: 4230: 4221: 4210: 4198: 4189: 4171: 4162: 4151: 4139: 4130: 4115: 4106: 4098: 4093: 4088: 4052: 4044: 4039: 4025: 4011: 3988: 3977: 3969: 3942: 3933: 3912: 3903: 3895: 3865: 3856: 3823: 3814: 3778: 3769: 3751: 3742: 3719: 3689: 3680: 3647: 3638: 3602: 3593: 3575: 3566: 3543: 3503: 3494: 3483: 3460: 3452: 3441: 3433: 3428: 3411: 3390: 3381: 3361: 3350: 3342: 3306: 3297: 3267: 3258: 3230: 3220: 3210: 3200: 3175: 3165: 3155: 3136: 3120: 3107: 3094: 3084: 3065: 3059: 3035: 3026: 2979: 2967:{\displaystyle r\otimes p\mapsto rp.rp=0} 2929: 2895: 2886: 2848: 2833: 2821: 2773: 2761: 2739: 2727: 2722: 2688: 2676: 2659: 2654: 2652: 2651: 2642: 2621: 2616: 2614: 2613: 2604: 2595: 2590:-modules. By the above we get that : 2554: 2543: 2538: 2536: 2535: 2524: 2519: 2517: 2516: 2511: 2482: 2465: 2453: 2444: 2310: 2262: 2241: 2236: 2234: 2233: 2224: 2203: 2198: 2196: 2195: 2186: 2177: 2131: 2126: 2124: 2123: 2106: 2101: 2099: 2098: 2090: 1966: 1958: 1953: 1951: 1931: 1923: 1918: 1916: 1896: 1894: 1874: 1866: 1861: 1853: 1845: 1840: 1820: 1818: 1792: 1791: 1778: 1777: 1769: 1737: 1717: 1697: 1668: 1642: 1612: 1586: 1566: 1534: 1515: 1514: 1501: 1500: 1492: 1460: 1441: 1440: 1438: 1407: 1406: 1404: 1385: 1384: 1382: 1363: 1362: 1360: 1341: 1340: 1338: 281: 276: 274: 273: 238: 233: 231: 230: 207: 158: 153: 151: 150: 133: 128: 126: 125: 111: 3014:{\displaystyle 0=rp\otimes 1=r\otimes p} 1981:is not torsion-free and thus not flat. 1289:modules, the sequence of abelian groups 4433: 3054:is composed only of pure tensors: For 4314:{\displaystyle I\otimes _{R}P\cong IP} 3327:{\displaystyle I\otimes _{R}P\cong IP} 4488:. Vol. 2 (2nd ed.). Dover. 4414:The exact functors between Quillen's 3285:{\displaystyle R\otimes _{R}P\cong P} 7: 4458:Jacobson (2009), p. 99, Theorem 3.1. 4440:Jacobson (2009), p. 98, Theorem 3.1. 2874:is the inclusion. Now, consider the 2085:having multiplicative identity. Let 4449:Jacobson (2009), p. 149, Prop. 3.9. 1663:is an element of the kernel. Then, 1377:-module. Therefore, tensoring with 2713:is also a short exact sequence of 2290:is also a short exact sequence of 14: 1130:) (this is commonly known as the 866:turns cokernels into cokernels"); 4262: 4246: 4222: 4190: 4163: 4131: 4107: 4094: 4053: 4040: 4026: 4012: 3978: 3934: 3904: 3770: 3594: 3461: 3442: 3429: 3412: 3351: 2006:consisting of all functors from 1967: 1954: 1932: 1919: 1897: 1875: 1862: 1854: 1846: 1821: 1637:, then it is zero. Suppose that 1529:is injective. One can show that 979:of abelian categories is exact. 966:turns kernels into cokernels"). 916:turns cokernels into kernels"); 4239: 4215: 4207: 4186: 4180: 4156: 4148: 4127: 3996: 3982: 3951: 3927: 3921: 3897: 3877: 3850: 3844: 3835: 3829: 3808: 3802: 3793: 3787: 3763: 3757: 3736: 3730: 3721: 3701: 3674: 3668: 3659: 3653: 3632: 3626: 3617: 3611: 3587: 3581: 3560: 3554: 3545: 3538:Proof: Consider a pure tensor 3369: 3355: 3236: 3193: 3181: 3148: 3126: 3100: 3047:{\displaystyle R\otimes _{R}P} 2940: 2904: 2857: 2838: 2830: 2811: 2805: 2793: 2770: 2751: 2697: 2655: 2617: 2562: 2539: 2520: 2473: 2459: 2396: 2390: 2381: 2369: 2348: 2342: 2333: 2321: 2271: 2237: 2199: 2145: 2127: 2102: 1858: 1850: 1782: 1679: 1673: 1505: 1471: 508:topological half-exact functor 313: 310: 304: 291: 285: 277: 267: 261: 248: 242: 234: 224: 218: 212: 172: 154: 129: 116: 1: 4421:The regular functors between 3334:. This proves the corollary. 1421:-module is an exact functor. 1192:the group of global sections 816:turns kernels into kernels"); 332:is a short exact sequence in 1904:{\displaystyle \mathbf {Z} } 1828:{\displaystyle \mathbf {Z} } 1757:{\displaystyle m\otimes q=0} 1554:{\displaystyle m\otimes q=0} 1448:{\displaystyle \mathbb {Z} } 1425:It suffices to show that if 1414:{\displaystyle \mathbb {Z} } 1392:{\displaystyle \mathbb {Q} } 1370:{\displaystyle \mathbb {Z} } 1348:{\displaystyle \mathbb {Q} } 3531:. We prove a special case: 1988:is an abelian category and 990:is an abelian category and 4659: 2039:by evaluating functors at 1656:{\displaystyle m\otimes q} 1626:{\displaystyle m\otimes q} 1223:, we can define a functor 18: 4542: 3512:{\displaystyle k=m/2^{n}} 91:(so that, in particular, 4467:Jacobson (2009), p. 156. 2717:-modules. By exactness, 2022:, then we get a functor 1581:is a torsion element or 1480:{\displaystyle i:M\to N} 1325:is exact if and only if 1046:is exact if and only if 4325:Properties and theorems 1732:is torsion. Therefore, 95:(0) = 0). We say that 4577:Essentially surjective 4345:right derived functors 4315: 4273: 4061: 3958: 3884: 3708: 3513: 3472: 3328: 3286: 3243: 3048: 3015: 2968: 2914: 2864: 2707: 2572: 2497: 2409: 2281: 2155: 1999:, we can consider the 1975: 1940: 1905: 1883: 1829: 1800: 1758: 1726: 1706: 1686: 1657: 1627: 1601: 1575: 1555: 1523: 1481: 1449: 1415: 1393: 1371: 1349: 977:equivalence or duality 530:, we similarly define 522:additive functor from 372:)β†’0 is also exact".) 323: 182: 4349:left derived functors 4316: 4274: 4062: 3959: 3885: 3709: 3514: 3473: 3329: 3287: 3244: 3049: 3016: 2969: 2915: 2865: 2708: 2582:is the inclusion and 2573: 2498: 2410: 2282: 2156: 2018:is a given object of 1976: 1941: 1906: 1884: 1830: 1801: 1759: 1727: 1707: 1687: 1658: 1628: 1602: 1576: 1556: 1524: 1482: 1450: 1416: 1394: 1372: 1350: 1234:category of all left 375:Further, we say that 324: 183: 44:short exact sequences 4398:to another category 4283: 4087: 3968: 3894: 3718: 3542: 3482: 3341: 3296: 3257: 3058: 3025: 2978: 2928: 2885: 2879:-module homomorphism 2721: 2594: 2510: 2443: 2309: 2176: 2163:short exact sequence 2089: 2014:; it is abelian. If 1950: 1915: 1893: 1839: 1817: 1768: 1736: 1716: 1696: 1685:{\displaystyle i(m)} 1667: 1641: 1611: 1585: 1565: 1533: 1491: 1459: 1437: 1403: 1381: 1359: 1337: 962:)β†’0 exact (i.e. if " 862:)β†’0 exact (i.e. if " 348:β†’0 is exact, then 0β†’ 206: 193:short exact sequence 110: 4638:Additive categories 4633:Homological algebra 4370:is right exact and 1806:is also injective. 1600:{\displaystyle q=0} 888:β†’0 exact implies 0β†’ 595:β†’0 is exact then 0β†’ 553:β†’0 is exact then 0β†’ 398:β†’0 is exact then 0β†’ 32:homological algebra 4423:regular categories 4311: 4269: 4057: 3954: 3890:. This shows that 3880: 3704: 3509: 3468: 3324: 3282: 3239: 3205: 3141: 3089: 3044: 3011: 2964: 2910: 2860: 2703: 2568: 2493: 2439:is as above, then 2419:This has a useful 2405: 2277: 2151: 1971: 1936: 1901: 1879: 1825: 1796: 1754: 1722: 1702: 1692:is torsion. Since 1682: 1653: 1623: 1597: 1571: 1551: 1519: 1477: 1445: 1411: 1389: 1367: 1345: 912:) exact (i.e. if " 812:) exact (i.e. if " 319: 178: 68:abelian categories 4620: 4619: 4592:Full and faithful 4495:978-0-486-47187-7 3196: 3132: 3080: 2670: 2632: 2548: 2529: 2294:-modules. (Since 2252: 2214: 2141: 2136: 2122: 2116: 2111: 2097: 1889:. Tensoring over 1725:{\displaystyle m} 1705:{\displaystyle i} 1574:{\displaystyle m} 1232:from the abelian 1200:) is left-exact. 1174:topological space 1035:of abelian groups 926:if and only if 0β†’ 838:β†’0 exact implies 776:if and only if 0β†’ 679:β†’0 is exact then 637:β†’0 is exact then 482:β†’0 is exact then 440:β†’0 is exact then 300: 295: 272: 257: 252: 229: 168: 163: 149: 143: 138: 124: 4650: 4528: 4521: 4514: 4505: 4499: 4482:Jacobson, Nathan 4468: 4465: 4459: 4456: 4450: 4447: 4441: 4438: 4416:exact categories 4320: 4318: 4317: 4312: 4298: 4297: 4278: 4276: 4275: 4270: 4265: 4257: 4249: 4235: 4234: 4225: 4214: 4203: 4202: 4193: 4176: 4175: 4166: 4155: 4144: 4143: 4134: 4120: 4119: 4110: 4102: 4097: 4066: 4064: 4063: 4058: 4056: 4048: 4043: 4029: 4015: 3992: 3981: 3963: 3961: 3960: 3955: 3947: 3946: 3937: 3917: 3916: 3907: 3889: 3887: 3886: 3881: 3876: 3875: 3860: 3828: 3827: 3818: 3783: 3782: 3773: 3756: 3755: 3746: 3713: 3711: 3710: 3705: 3700: 3699: 3684: 3652: 3651: 3642: 3607: 3606: 3597: 3580: 3579: 3570: 3518: 3516: 3515: 3510: 3508: 3507: 3498: 3477: 3475: 3474: 3469: 3464: 3456: 3445: 3437: 3432: 3415: 3395: 3394: 3385: 3365: 3354: 3333: 3331: 3330: 3325: 3311: 3310: 3291: 3289: 3288: 3283: 3272: 3271: 3248: 3246: 3245: 3240: 3235: 3234: 3225: 3224: 3215: 3214: 3204: 3180: 3179: 3170: 3169: 3160: 3159: 3140: 3125: 3124: 3112: 3111: 3099: 3098: 3088: 3070: 3069: 3053: 3051: 3050: 3045: 3040: 3039: 3020: 3018: 3017: 3012: 2973: 2971: 2970: 2965: 2919: 2917: 2916: 2911: 2900: 2899: 2869: 2867: 2866: 2861: 2853: 2852: 2837: 2826: 2825: 2777: 2766: 2765: 2744: 2743: 2731: 2712: 2710: 2709: 2704: 2693: 2692: 2680: 2672: 2671: 2669: 2658: 2653: 2647: 2646: 2634: 2633: 2631: 2620: 2615: 2609: 2608: 2577: 2575: 2574: 2569: 2558: 2550: 2549: 2547: 2542: 2537: 2531: 2530: 2528: 2523: 2518: 2502: 2500: 2499: 2494: 2486: 2469: 2458: 2457: 2414: 2412: 2411: 2406: 2286: 2284: 2283: 2278: 2267: 2266: 2254: 2253: 2251: 2240: 2235: 2229: 2228: 2216: 2215: 2213: 2202: 2197: 2191: 2190: 2169:-modules. Then 2160: 2158: 2157: 2152: 2139: 2138: 2137: 2135: 2130: 2125: 2120: 2114: 2113: 2112: 2110: 2105: 2100: 2095: 2080:commutative ring 2001:functor category 1992:is an arbitrary 1980: 1978: 1977: 1972: 1970: 1962: 1957: 1945: 1943: 1942: 1937: 1935: 1927: 1922: 1910: 1908: 1907: 1902: 1900: 1888: 1886: 1885: 1880: 1878: 1870: 1865: 1857: 1849: 1834: 1832: 1831: 1826: 1824: 1805: 1803: 1802: 1797: 1795: 1781: 1763: 1761: 1760: 1755: 1731: 1729: 1728: 1723: 1711: 1709: 1708: 1703: 1691: 1689: 1688: 1683: 1662: 1660: 1659: 1654: 1632: 1630: 1629: 1624: 1606: 1604: 1603: 1598: 1580: 1578: 1577: 1572: 1560: 1558: 1557: 1552: 1528: 1526: 1525: 1520: 1518: 1504: 1486: 1484: 1483: 1478: 1454: 1452: 1451: 1446: 1444: 1420: 1418: 1417: 1412: 1410: 1398: 1396: 1395: 1390: 1388: 1376: 1374: 1373: 1368: 1366: 1354: 1352: 1351: 1346: 1344: 994:is an object of 788:exact implies 0β†’ 328: 326: 325: 320: 298: 297: 296: 294: 280: 275: 270: 255: 254: 253: 251: 237: 232: 227: 187: 185: 184: 179: 166: 165: 164: 162: 157: 152: 147: 141: 140: 139: 137: 132: 127: 122: 89:additive functor 83: 21:regular category 4658: 4657: 4653: 4652: 4651: 4649: 4648: 4647: 4623: 4622: 4621: 4616: 4538: 4532: 4502: 4496: 4480: 4476: 4471: 4466: 4462: 4457: 4453: 4448: 4444: 4439: 4435: 4431: 4380: 4378:Generalizations 4374:is left exact. 4327: 4289: 4281: 4280: 4226: 4194: 4167: 4135: 4111: 4085: 4084: 3966: 3965: 3938: 3908: 3892: 3891: 3861: 3819: 3774: 3747: 3716: 3715: 3685: 3643: 3598: 3571: 3540: 3539: 3523:is the highest 3499: 3480: 3479: 3386: 3339: 3338: 3302: 3294: 3293: 3263: 3255: 3254: 3226: 3216: 3206: 3171: 3161: 3151: 3116: 3103: 3090: 3061: 3056: 3055: 3031: 3023: 3022: 2976: 2975: 2926: 2925: 2891: 2883: 2882: 2844: 2817: 2757: 2735: 2719: 2718: 2684: 2638: 2600: 2592: 2591: 2508: 2507: 2449: 2441: 2440: 2307: 2306: 2258: 2220: 2182: 2174: 2173: 2087: 2086: 2078:-modules for a 2051: 2043:. This functor 2030: 1948: 1947: 1913: 1912: 1891: 1890: 1837: 1836: 1815: 1814: 1809:In general, if 1766: 1765: 1734: 1733: 1714: 1713: 1694: 1693: 1665: 1664: 1639: 1638: 1609: 1608: 1583: 1582: 1563: 1562: 1561:if and only if 1531: 1530: 1489: 1488: 1457: 1456: 1435: 1434: 1401: 1400: 1379: 1378: 1357: 1356: 1335: 1334: 1333:. For example, 1324: 1313:β†’ 0 is exact. 1260: 1231: 1161:-vector spaces 1121: 1072: 1062: 1045: 1016: 1006: 973: 876:if and only if 826:if and only if 730:if and only if 204: 203: 108: 107: 71: 56: 42:that preserves 30:, particularly 24: 17: 12: 11: 5: 4656: 4654: 4646: 4645: 4640: 4635: 4625: 4624: 4618: 4617: 4615: 4614: 4609: 4604: 4599: 4594: 4589: 4584: 4579: 4574: 4569: 4564: 4559: 4554: 4549: 4543: 4540: 4539: 4533: 4531: 4530: 4523: 4516: 4508: 4501: 4500: 4494: 4477: 4475: 4472: 4470: 4469: 4460: 4451: 4442: 4432: 4430: 4427: 4404: 4403: 4379: 4376: 4326: 4323: 4310: 4307: 4304: 4301: 4296: 4292: 4288: 4268: 4264: 4260: 4256: 4252: 4248: 4244: 4241: 4238: 4233: 4229: 4224: 4220: 4217: 4213: 4209: 4206: 4201: 4197: 4192: 4188: 4185: 4182: 4179: 4174: 4170: 4165: 4161: 4158: 4154: 4150: 4147: 4142: 4138: 4133: 4129: 4126: 4123: 4118: 4114: 4109: 4105: 4101: 4096: 4092: 4055: 4051: 4047: 4042: 4038: 4035: 4032: 4028: 4024: 4021: 4018: 4014: 4010: 4007: 4004: 4001: 3998: 3995: 3991: 3987: 3984: 3980: 3976: 3973: 3953: 3950: 3945: 3941: 3936: 3932: 3929: 3926: 3923: 3920: 3915: 3911: 3906: 3902: 3899: 3879: 3874: 3871: 3868: 3864: 3859: 3855: 3852: 3849: 3846: 3843: 3840: 3837: 3834: 3831: 3826: 3822: 3817: 3813: 3810: 3807: 3804: 3801: 3798: 3795: 3792: 3789: 3786: 3781: 3777: 3772: 3768: 3765: 3762: 3759: 3754: 3750: 3745: 3741: 3738: 3735: 3732: 3729: 3726: 3723: 3703: 3698: 3695: 3692: 3688: 3683: 3679: 3676: 3673: 3670: 3667: 3664: 3661: 3658: 3655: 3650: 3646: 3641: 3637: 3634: 3631: 3628: 3625: 3622: 3619: 3616: 3613: 3610: 3605: 3601: 3596: 3592: 3589: 3586: 3583: 3578: 3574: 3569: 3565: 3562: 3559: 3556: 3553: 3550: 3547: 3506: 3502: 3497: 3493: 3490: 3487: 3467: 3463: 3459: 3455: 3451: 3448: 3444: 3440: 3436: 3431: 3427: 3424: 3421: 3418: 3414: 3410: 3407: 3404: 3401: 3398: 3393: 3389: 3384: 3380: 3377: 3374: 3371: 3368: 3364: 3360: 3357: 3353: 3349: 3346: 3323: 3320: 3317: 3314: 3309: 3305: 3301: 3281: 3278: 3275: 3270: 3266: 3262: 3238: 3233: 3229: 3223: 3219: 3213: 3209: 3203: 3199: 3195: 3192: 3189: 3186: 3183: 3178: 3174: 3168: 3164: 3158: 3154: 3150: 3147: 3144: 3139: 3135: 3131: 3128: 3123: 3119: 3115: 3110: 3106: 3102: 3097: 3093: 3087: 3083: 3079: 3076: 3073: 3068: 3064: 3043: 3038: 3034: 3030: 3010: 3007: 3004: 3001: 2998: 2995: 2992: 2989: 2986: 2983: 2963: 2960: 2957: 2954: 2951: 2948: 2945: 2942: 2939: 2936: 2933: 2909: 2906: 2903: 2898: 2894: 2890: 2859: 2856: 2851: 2847: 2843: 2840: 2836: 2832: 2829: 2824: 2820: 2816: 2813: 2810: 2807: 2804: 2801: 2798: 2795: 2792: 2789: 2786: 2783: 2780: 2776: 2772: 2769: 2764: 2760: 2756: 2753: 2750: 2747: 2742: 2738: 2734: 2730: 2726: 2702: 2699: 2696: 2691: 2687: 2683: 2679: 2675: 2668: 2665: 2662: 2657: 2650: 2645: 2641: 2637: 2630: 2627: 2624: 2619: 2612: 2607: 2603: 2599: 2567: 2564: 2561: 2557: 2553: 2546: 2541: 2534: 2527: 2522: 2515: 2492: 2489: 2485: 2481: 2478: 2475: 2472: 2468: 2464: 2461: 2456: 2452: 2448: 2417: 2416: 2404: 2401: 2398: 2395: 2392: 2389: 2386: 2383: 2380: 2377: 2374: 2371: 2368: 2365: 2362: 2359: 2356: 2353: 2350: 2347: 2344: 2341: 2338: 2335: 2332: 2329: 2326: 2323: 2320: 2317: 2314: 2288: 2287: 2276: 2273: 2270: 2265: 2261: 2257: 2250: 2247: 2244: 2239: 2232: 2227: 2223: 2219: 2212: 2209: 2206: 2201: 2194: 2189: 2185: 2181: 2150: 2147: 2144: 2134: 2129: 2119: 2109: 2104: 2094: 2047: 2026: 1969: 1965: 1961: 1956: 1934: 1930: 1926: 1921: 1899: 1877: 1873: 1869: 1864: 1860: 1856: 1852: 1848: 1844: 1823: 1794: 1790: 1787: 1784: 1780: 1776: 1773: 1753: 1750: 1747: 1744: 1741: 1721: 1712:is injective, 1701: 1681: 1678: 1675: 1672: 1652: 1649: 1646: 1622: 1619: 1616: 1596: 1593: 1590: 1570: 1550: 1547: 1544: 1541: 1538: 1517: 1513: 1510: 1507: 1503: 1499: 1496: 1476: 1473: 1470: 1467: 1464: 1443: 1409: 1387: 1365: 1343: 1320: 1256: 1246:tensor product 1227: 1182:abelian groups 1140:-vector spaces 1117: 1116: * = Hom 1068: 1058: 1054:. The functor 1041: 1037:. The functor 1012: 1002: 972: 969: 968: 967: 938:exact implies 917: 867: 817: 767: 742:exact implies 705: 704: 667:if whenever 0β†’ 662: 625:if whenever 0β†’ 620: 583:if whenever 0β†’ 578: 541:if whenever 0β†’ 512: 511: 470:if whenever 0β†’ 465: 428:if whenever 0β†’ 423: 386:if whenever 0β†’ 330: 329: 318: 315: 312: 309: 306: 303: 293: 290: 287: 284: 279: 269: 266: 263: 260: 250: 247: 244: 241: 236: 226: 223: 220: 217: 214: 211: 189: 188: 177: 174: 171: 161: 156: 146: 136: 131: 121: 118: 115: 55: 52: 15: 13: 10: 9: 6: 4: 3: 2: 4655: 4644: 4641: 4639: 4636: 4634: 4631: 4630: 4628: 4613: 4610: 4608: 4607:Representable 4605: 4603: 4600: 4598: 4595: 4593: 4590: 4588: 4585: 4583: 4580: 4578: 4575: 4573: 4570: 4568: 4565: 4563: 4560: 4558: 4555: 4553: 4550: 4548: 4545: 4544: 4541: 4536: 4529: 4524: 4522: 4517: 4515: 4510: 4509: 4506: 4497: 4491: 4487: 4486:Basic algebra 4483: 4479: 4478: 4473: 4464: 4461: 4455: 4452: 4446: 4443: 4437: 4434: 4428: 4426: 4424: 4419: 4417: 4412: 4410: 4401: 4397: 4393: 4389: 4388: 4387: 4385: 4377: 4375: 4373: 4369: 4365: 4361: 4357: 4352: 4350: 4346: 4341: 4339: 4335: 4330: 4324: 4322: 4308: 4305: 4302: 4299: 4294: 4290: 4286: 4266: 4258: 4254: 4250: 4242: 4236: 4231: 4227: 4218: 4211: 4204: 4199: 4195: 4183: 4177: 4172: 4168: 4159: 4152: 4145: 4140: 4136: 4124: 4121: 4116: 4112: 4103: 4099: 4090: 4082: 4078: 4074: 4070: 4049: 4045: 4036: 4033: 4030: 4022: 4019: 4016: 4008: 4005: 4002: 3999: 3993: 3989: 3985: 3974: 3971: 3948: 3943: 3939: 3930: 3924: 3918: 3913: 3909: 3900: 3872: 3869: 3866: 3862: 3857: 3853: 3847: 3841: 3838: 3832: 3824: 3820: 3815: 3811: 3805: 3799: 3796: 3790: 3784: 3779: 3775: 3766: 3760: 3752: 3748: 3743: 3739: 3733: 3727: 3724: 3696: 3693: 3690: 3686: 3681: 3677: 3671: 3665: 3662: 3656: 3648: 3644: 3639: 3635: 3629: 3623: 3620: 3614: 3608: 3603: 3599: 3590: 3584: 3576: 3572: 3567: 3563: 3557: 3551: 3548: 3536: 3534: 3530: 3526: 3522: 3504: 3500: 3495: 3491: 3488: 3485: 3465: 3457: 3453: 3449: 3446: 3438: 3434: 3425: 3422: 3419: 3408: 3405: 3402: 3399: 3396: 3391: 3387: 3382: 3378: 3372: 3366: 3362: 3358: 3347: 3344: 3335: 3321: 3318: 3315: 3312: 3307: 3303: 3299: 3292:. Similarly, 3279: 3276: 3273: 3268: 3264: 3260: 3252: 3231: 3227: 3221: 3217: 3211: 3207: 3201: 3197: 3190: 3187: 3184: 3176: 3172: 3166: 3162: 3156: 3152: 3145: 3142: 3137: 3133: 3129: 3121: 3117: 3113: 3108: 3104: 3095: 3091: 3085: 3081: 3077: 3074: 3071: 3066: 3062: 3041: 3036: 3032: 3028: 3008: 3005: 3002: 2999: 2996: 2993: 2990: 2987: 2984: 2981: 2974:implies that 2961: 2958: 2955: 2952: 2949: 2946: 2943: 2937: 2934: 2931: 2923: 2907: 2901: 2896: 2892: 2888: 2880: 2878: 2873: 2854: 2849: 2845: 2841: 2834: 2827: 2822: 2818: 2814: 2808: 2802: 2799: 2796: 2790: 2787: 2784: 2781: 2778: 2774: 2767: 2762: 2758: 2754: 2748: 2745: 2740: 2736: 2732: 2728: 2724: 2716: 2700: 2694: 2689: 2685: 2681: 2677: 2673: 2666: 2663: 2660: 2648: 2643: 2639: 2635: 2628: 2625: 2622: 2610: 2605: 2601: 2597: 2589: 2585: 2581: 2565: 2559: 2555: 2551: 2544: 2532: 2525: 2513: 2504: 2490: 2487: 2483: 2479: 2476: 2470: 2466: 2462: 2454: 2450: 2446: 2438: 2434: 2430: 2426: 2422: 2402: 2399: 2393: 2387: 2384: 2378: 2375: 2372: 2366: 2363: 2360: 2357: 2354: 2351: 2345: 2339: 2336: 2330: 2327: 2324: 2318: 2315: 2312: 2305: 2304: 2303: 2301: 2297: 2293: 2274: 2268: 2263: 2259: 2255: 2248: 2245: 2242: 2230: 2225: 2221: 2217: 2210: 2207: 2204: 2192: 2187: 2183: 2179: 2172: 2171: 2170: 2168: 2164: 2148: 2142: 2132: 2117: 2107: 2092: 2084: 2081: 2077: 2073: 2069: 2065: 2061: 2058:Theorem: Let 2056: 2053: 2050: 2046: 2042: 2038: 2034: 2029: 2025: 2021: 2017: 2013: 2009: 2005: 2002: 1998: 1995: 1991: 1987: 1982: 1963: 1959: 1928: 1924: 1871: 1867: 1842: 1812: 1807: 1788: 1785: 1774: 1771: 1764:. Therefore, 1751: 1748: 1745: 1742: 1739: 1719: 1699: 1676: 1670: 1650: 1647: 1644: 1636: 1620: 1617: 1614: 1594: 1591: 1588: 1568: 1548: 1545: 1542: 1539: 1536: 1511: 1508: 1497: 1494: 1474: 1468: 1465: 1462: 1432: 1431:injective map 1428: 1424: 1332: 1328: 1323: 1319: 1314: 1312: 1308: 1304: 1300: 1296: 1292: 1288: 1284: 1280: 1276: 1272: 1268: 1264: 1259: 1255: 1251: 1247: 1244:by using the 1243: 1239: 1237: 1230: 1226: 1222: 1218: 1214: 1210: 1206: 1201: 1199: 1195: 1191: 1187: 1183: 1179: 1175: 1171: 1166: 1164: 1160: 1156: 1152: 1149: 1145: 1141: 1139: 1133: 1129: 1125: 1120: 1115: 1111: 1107: 1103: 1099: 1095: 1090: 1088: 1084: 1080: 1076: 1071: 1066: 1061: 1057: 1053: 1049: 1044: 1040: 1036: 1034: 1028: 1024: 1020: 1015: 1010: 1005: 1001: 997: 993: 989: 985: 980: 978: 970: 965: 961: 957: 953: 949: 945: 941: 937: 933: 929: 925: 921: 918: 915: 911: 907: 903: 899: 895: 891: 887: 883: 879: 875: 871: 868: 865: 861: 857: 853: 849: 845: 841: 837: 833: 829: 825: 821: 818: 815: 811: 807: 803: 799: 795: 791: 787: 783: 779: 775: 771: 768: 765: 761: 757: 753: 749: 745: 741: 737: 733: 729: 725: 722: 721: 720: 718: 714: 710: 702: 698: 694: 690: 686: 682: 678: 674: 670: 666: 663: 661:)β†’0 is exact; 660: 656: 652: 648: 644: 640: 636: 632: 628: 624: 621: 618: 614: 610: 606: 602: 598: 594: 590: 586: 582: 579: 577:)β†’0 is exact; 576: 572: 568: 564: 560: 556: 552: 548: 544: 540: 537: 536: 535: 533: 529: 525: 521: 520:contravariant 517: 509: 505: 501: 497: 493: 489: 485: 481: 477: 473: 469: 466: 464:)β†’0 is exact; 463: 459: 455: 451: 447: 443: 439: 435: 431: 427: 424: 421: 417: 413: 409: 405: 401: 397: 393: 389: 385: 382: 381: 380: 378: 373: 371: 367: 363: 359: 355: 351: 347: 343: 339: 335: 316: 307: 301: 288: 282: 264: 258: 245: 239: 221: 215: 209: 202: 201: 200: 198: 194: 175: 169: 159: 144: 134: 119: 113: 106: 105: 104: 103:if whenever 102: 101:exact functor 98: 94: 90: 87: 82: 78: 74: 69: 65: 61: 53: 51: 49: 45: 41: 37: 36:exact functor 33: 29: 22: 4581: 4557:Conservative 4485: 4463: 4454: 4445: 4436: 4420: 4413: 4408: 4405: 4399: 4395: 4391: 4381: 4371: 4367: 4363: 4360:left adjoint 4355: 4353: 4342: 4331: 4328: 4076: 4072: 4068: 3714:. Also, for 3537: 3532: 3528: 3520: 3336: 2921: 2876: 2871: 2714: 2587: 2583: 2579: 2505: 2436: 2432: 2424: 2418: 2299: 2295: 2291: 2289: 2166: 2082: 2075: 2071: 2067: 2063: 2059: 2057: 2054: 2048: 2044: 2040: 2036: 2032: 2027: 2023: 2019: 2015: 2011: 2007: 2003: 1989: 1985: 1983: 1810: 1808: 1426: 1422: 1326: 1321: 1317: 1316:The functor 1315: 1310: 1306: 1302: 1298: 1294: 1290: 1286: 1282: 1278: 1274: 1270: 1266: 1262: 1257: 1253: 1249: 1241: 1235: 1228: 1224: 1216: 1212: 1204: 1202: 1197: 1193: 1189: 1185: 1169: 1167: 1158: 1150: 1143: 1137: 1136:category of 1127: 1123: 1118: 1113: 1109: 1106:vector space 1101: 1093: 1091: 1082: 1078: 1074: 1069: 1064: 1059: 1055: 1047: 1042: 1038: 1032: 1026: 1022: 1018: 1013: 1008: 1003: 999: 995: 991: 987: 984:Hom functors 981: 974: 963: 959: 955: 951: 947: 943: 939: 935: 931: 927: 923: 919: 913: 909: 905: 901: 897: 893: 889: 885: 881: 877: 873: 869: 863: 859: 855: 851: 847: 843: 839: 835: 831: 827: 823: 819: 813: 809: 805: 801: 797: 793: 789: 785: 781: 777: 773: 769: 763: 759: 755: 751: 747: 743: 739: 735: 731: 727: 723: 716: 712: 708: 706: 700: 696: 692: 688: 684: 680: 676: 672: 668: 664: 658: 654: 650: 646: 642: 638: 634: 630: 626: 622: 616: 612: 608: 604: 600: 596: 592: 588: 584: 580: 574: 570: 566: 562: 558: 554: 550: 546: 542: 538: 531: 527: 523: 515: 513: 503: 499: 495: 491: 487: 483: 479: 475: 471: 467: 461: 457: 453: 449: 445: 441: 437: 433: 429: 425: 419: 415: 411: 407: 403: 399: 395: 391: 387: 383: 376: 374: 369: 365: 361: 357: 353: 349: 345: 341: 337: 333: 331: 196: 190: 100: 96: 92: 80: 76: 72: 63: 59: 57: 47: 35: 25: 1285:β†’0 of left 1215:is a right 1112:, we write 924:right-exact 824:right-exact 703:) is exact. 623:right-exact 619:) is exact; 426:right-exact 422:) is exact; 54:Definitions 28:mathematics 4627:Categories 4474:References 3964:. Letting 3525:power of 2 2052:is exact. 1633:is in the 1355:is a flat 1132:dual space 1052:projective 874:left-exact 774:left-exact 665:half-exact 581:left-exact 468:half-exact 384:left-exact 70:, and let 4587:Forgetful 4303:≅ 4291:⊗ 4243:≅ 4228:⊗ 4196:⊗ 4169:⊗ 4137:⊗ 4125:≅ 4113:⊗ 3940:⊗ 3910:⊗ 3848:⊗ 3806:⊗ 3776:⊗ 3761:∈ 3734:⊗ 3694:− 3672:⊗ 3630:⊗ 3600:⊗ 3585:∈ 3558:⊗ 3527:dividing 3447:≅ 3426:⊗ 3409:∈ 3316:≅ 3304:⊗ 3277:≅ 3265:⊗ 3198:∑ 3191:⊗ 3146:⊗ 3134:∑ 3114:⊗ 3082:∑ 3072:∈ 3033:⊗ 3006:⊗ 2994:⊗ 2941:↦ 2935:⊗ 2920:given by 2905:→ 2893:⊗ 2846:⊗ 2819:⊗ 2800:⊗ 2759:⊗ 2749:≅ 2737:⊗ 2698:→ 2686:⊗ 2664:⊗ 2656:→ 2640:⊗ 2626:⊗ 2618:→ 2602:⊗ 2563:→ 2540:→ 2521:→ 2477:≅ 2451:⊗ 2421:corollary 2400:⊗ 2376:⊗ 2364:⊗ 2352:⊗ 2328:⊗ 2316:⊗ 2272:→ 2260:⊗ 2246:⊗ 2238:→ 2222:⊗ 2208:⊗ 2200:→ 2184:⊗ 2146:→ 2128:→ 2103:→ 1859:↠ 1851:↪ 1835:-modules 1789:⊗ 1783:→ 1775:⊗ 1743:⊗ 1648:⊗ 1618:⊗ 1540:⊗ 1512:⊗ 1506:→ 1498:⊗ 1472:→ 1455:-modules 1148:injective 1087:injective 1031:category 314:→ 278:⟶ 235:⟶ 213:→ 173:→ 155:→ 130:→ 117:→ 86:covariant 4643:Functors 4602:Monoidal 4572:Enriched 4567:Diagonal 4547:Additive 4484:(2009). 4400:C′ 4338:colimits 2870:, since 2578:, where 1997:category 1238:-modules 971:Examples 766:) exact; 4597:Logical 4562:Derived 4552:Adjoint 4535:Functor 4366:, then 4081:theorem 4069:A,B,C,P 2506:Proof: 1178:sheaves 1067:) = Hom 1029:to the 1011:) = Hom 998:, then 40:functor 4612:Smooth 4492:  4334:limits 3478:where 3253:. So, 2427:is an 2140:  2121:  2115:  2096:  1635:kernel 1429:is an 1423:Proof: 1221:module 1163:splits 1155:module 1146:is an 975:Every 534:to be 379:is 299:  271:  256:  228:  199:then 167:  148:  142:  123:  99:is an 4582:Exact 4537:types 4429:Notes 3535:=12. 2881:from 2429:ideal 2423:: If 2161:be a 2031:from 1994:small 1911:with 1399:as a 1248:over 1207:is a 1172:is a 1108:over 1104:is a 1098:field 1096:is a 986:: if 728:exact 539:exact 518:is a 191:is a 84:be a 38:is a 34:, an 4490:ISBN 4390:Let 4384:SGA4 4071:are 3519:and 3251:onto 2435:and 2165:of 2070:and 1331:flat 1265:) = 1211:and 1209:ring 1100:and 62:and 58:Let 48:fail 4382:In 4362:to 4358:is 4067:, 2431:of 2074:be 2035:to 2010:to 1984:If 1433:of 1329:is 1240:to 1203:If 1184:on 1180:of 1168:If 1092:If 1085:is 1050:is 922:is 872:is 822:is 772:is 726:is 526:to 514:If 195:in 66:be 26:In 4629:: 4411:. 4351:. 4321:. 4160:12 4104:12 4050:12 4009:12 3901:12 3839:12 3621:12 3591:12 3549:12 3373::= 2503:. 2385::= 2337::= 1309:βŠ— 1305:β†’ 1301:βŠ— 1297:β†’ 1293:βŠ— 1269:βŠ— 1252:: 1242:Ab 1089:. 1033:Ab 954:)β†’ 946:)β†’ 904:)β†’ 896:)β†’ 854:)β†’ 846:)β†’ 804:)β†’ 796:)β†’ 758:)β†’ 750:)β†’ 695:)β†’ 687:)β†’ 653:)β†’ 645:)β†’ 611:)β†’ 603:)β†’ 569:)β†’ 561:)β†’ 498:)β†’ 490:)β†’ 456:)β†’ 448:)β†’ 414:)β†’ 406:)β†’ 364:)β†’ 356:)β†’ 75:: 4527:e 4520:t 4513:v 4498:. 4409:C 4396:C 4392:C 4372:G 4368:F 4364:G 4356:F 4309:P 4306:I 4300:P 4295:R 4287:I 4267:P 4263:Z 4259:3 4255:/ 4251:P 4247:Z 4240:) 4237:P 4232:Z 4223:Z 4219:3 4216:( 4212:/ 4208:) 4205:P 4200:Z 4191:Z 4187:( 4184:= 4181:) 4178:P 4173:Z 4164:Z 4157:( 4153:/ 4149:) 4146:P 4141:Z 4132:Z 4128:( 4122:P 4117:Z 4108:Z 4100:/ 4095:Z 4091:: 4077:Z 4075:= 4073:R 4054:Z 4046:/ 4041:Z 4037:= 4034:C 4031:, 4027:Z 4023:= 4020:B 4017:, 4013:Z 4006:= 4003:A 4000:, 3997:] 3994:2 3990:/ 3986:1 3983:[ 3979:Z 3975:= 3972:P 3952:) 3949:P 3944:Z 3935:Z 3931:3 3928:( 3925:= 3922:) 3919:P 3914:Z 3905:Z 3898:( 3878:) 3873:2 3870:+ 3867:k 3863:2 3858:/ 3854:a 3851:( 3845:) 3842:z 3836:( 3833:= 3830:) 3825:k 3821:2 3816:/ 3812:a 3809:( 3803:) 3800:z 3797:3 3794:( 3791:, 3788:) 3785:P 3780:Z 3771:Z 3767:3 3764:( 3758:) 3753:k 3749:2 3744:/ 3740:a 3737:( 3731:) 3728:z 3725:3 3722:( 3702:) 3697:2 3691:k 3687:2 3682:/ 3678:a 3675:( 3669:) 3666:z 3663:3 3660:( 3657:= 3654:) 3649:k 3645:2 3640:/ 3636:a 3633:( 3627:) 3624:z 3618:( 3615:. 3612:) 3609:P 3604:Z 3595:Z 3588:( 3582:) 3577:k 3573:2 3568:/ 3564:a 3561:( 3555:) 3552:z 3546:( 3533:m 3529:m 3521:n 3505:n 3501:2 3496:/ 3492:m 3489:= 3486:k 3466:P 3462:Z 3458:k 3454:/ 3450:P 3443:Z 3439:m 3435:/ 3430:Z 3423:P 3420:, 3417:} 3413:Z 3406:k 3403:, 3400:a 3397:: 3392:k 3388:2 3383:/ 3379:a 3376:{ 3370:] 3367:2 3363:/ 3359:1 3356:[ 3352:Z 3348:= 3345:P 3322:P 3319:I 3313:P 3308:R 3300:I 3280:P 3274:P 3269:R 3261:R 3237:) 3232:i 3228:p 3222:i 3218:x 3212:i 3208:r 3202:i 3194:( 3188:1 3185:= 3182:) 3177:i 3173:p 3167:i 3163:x 3157:i 3153:r 3149:( 3143:1 3138:i 3130:= 3127:) 3122:i 3118:p 3109:i 3105:r 3101:( 3096:i 3092:x 3086:i 3078:, 3075:R 3067:i 3063:x 3042:P 3037:R 3029:R 3009:p 3003:r 3000:= 2997:1 2991:p 2988:r 2985:= 2982:0 2962:0 2959:= 2956:p 2953:r 2950:. 2947:p 2944:r 2938:p 2932:r 2922:R 2908:P 2902:P 2897:R 2889:R 2877:R 2872:f 2858:) 2855:P 2850:R 2842:I 2839:( 2835:/ 2831:) 2828:P 2823:R 2815:R 2812:( 2809:= 2806:) 2803:P 2797:f 2794:( 2791:e 2788:g 2785:a 2782:m 2779:I 2775:/ 2771:) 2768:P 2763:R 2755:R 2752:( 2746:P 2741:R 2733:I 2729:/ 2725:R 2715:R 2701:0 2695:P 2690:R 2682:I 2678:/ 2674:R 2667:P 2661:g 2649:P 2644:R 2636:R 2629:P 2623:f 2611:P 2606:R 2598:I 2588:R 2584:g 2580:f 2566:0 2560:I 2556:/ 2552:R 2545:g 2533:R 2526:f 2514:I 2491:P 2488:I 2484:/ 2480:P 2474:) 2471:I 2467:/ 2463:R 2460:( 2455:R 2447:P 2437:P 2433:R 2425:I 2415:. 2403:p 2397:) 2394:b 2391:( 2388:g 2382:) 2379:p 2373:b 2370:( 2367:P 2361:g 2358:, 2355:p 2349:) 2346:a 2343:( 2340:f 2334:) 2331:p 2325:a 2322:( 2319:P 2313:f 2300:R 2296:R 2292:R 2275:0 2269:P 2264:R 2256:C 2249:P 2243:g 2231:P 2226:R 2218:B 2211:P 2205:f 2193:P 2188:R 2180:A 2167:R 2149:0 2143:C 2133:g 2118:B 2108:f 2093:A 2083:R 2076:R 2072:P 2068:C 2066:, 2064:B 2062:, 2060:A 2049:X 2045:E 2041:X 2037:A 2033:A 2028:X 2024:E 2020:C 2016:X 2012:A 2008:C 2004:A 1990:C 1986:A 1968:Z 1964:5 1960:/ 1955:Z 1933:Z 1929:5 1925:/ 1920:Z 1898:Z 1876:Z 1872:5 1868:/ 1863:Z 1855:Z 1847:Z 1843:5 1822:Z 1811:T 1793:Q 1786:N 1779:Q 1772:M 1752:0 1749:= 1746:q 1740:m 1720:m 1700:i 1680:) 1677:m 1674:( 1671:i 1651:q 1645:m 1621:q 1615:m 1595:0 1592:= 1589:q 1569:m 1549:0 1546:= 1543:q 1537:m 1516:Q 1509:N 1502:Q 1495:M 1475:N 1469:M 1466:: 1463:i 1442:Z 1427:i 1408:Z 1386:Q 1364:Z 1342:Q 1327:T 1322:T 1318:H 1311:C 1307:T 1303:B 1299:T 1295:A 1291:T 1287:R 1283:C 1281:β†’ 1279:B 1277:β†’ 1275:A 1271:X 1267:T 1263:X 1261:( 1258:T 1254:H 1250:R 1236:R 1229:T 1225:H 1219:- 1217:R 1213:T 1205:R 1198:X 1196:( 1194:F 1190:F 1186:X 1170:X 1159:k 1153:- 1151:k 1144:k 1138:k 1128:k 1126:, 1124:V 1122:( 1119:k 1114:V 1110:k 1102:V 1094:k 1083:A 1079:A 1077:, 1075:X 1073:( 1070:A 1065:X 1063:( 1060:A 1056:G 1048:A 1043:A 1039:F 1027:A 1023:X 1021:, 1019:A 1017:( 1014:A 1009:X 1007:( 1004:A 1000:F 996:A 992:A 988:A 964:G 960:A 958:( 956:G 952:B 950:( 948:G 944:C 942:( 940:G 936:C 934:β†’ 932:B 930:β†’ 928:A 920:G 914:G 910:A 908:( 906:G 902:B 900:( 898:G 894:C 892:( 890:G 886:C 884:β†’ 882:B 880:β†’ 878:A 870:G 864:F 860:C 858:( 856:F 852:B 850:( 848:F 844:A 842:( 840:F 836:C 834:β†’ 832:B 830:β†’ 828:A 820:F 814:F 810:C 808:( 806:F 802:B 800:( 798:F 794:A 792:( 790:F 786:C 784:β†’ 782:B 780:β†’ 778:A 770:F 764:C 762:( 760:F 756:B 754:( 752:F 748:A 746:( 744:F 740:C 738:β†’ 736:B 734:β†’ 732:A 724:F 717:C 715:β†’ 713:B 711:β†’ 709:A 701:A 699:( 697:G 693:B 691:( 689:G 685:C 683:( 681:G 677:C 675:β†’ 673:B 671:β†’ 669:A 659:A 657:( 655:G 651:B 649:( 647:G 643:C 641:( 639:G 635:C 633:β†’ 631:B 629:β†’ 627:A 617:A 615:( 613:G 609:B 607:( 605:G 601:C 599:( 597:G 593:C 591:β†’ 589:B 587:β†’ 585:A 575:A 573:( 571:G 567:B 565:( 563:G 559:C 557:( 555:G 551:C 549:β†’ 547:B 545:β†’ 543:A 532:G 528:Q 524:P 516:G 510:. 504:C 502:( 500:F 496:B 494:( 492:F 488:A 486:( 484:F 480:C 478:β†’ 476:B 474:β†’ 472:A 462:C 460:( 458:F 454:B 452:( 450:F 446:A 444:( 442:F 438:C 436:β†’ 434:B 432:β†’ 430:A 420:C 418:( 416:F 412:B 410:( 408:F 404:A 402:( 400:F 396:C 394:β†’ 392:B 390:β†’ 388:A 377:F 370:C 368:( 366:F 362:B 360:( 358:F 354:A 352:( 350:F 346:C 344:β†’ 342:B 340:β†’ 338:A 334:Q 317:0 311:) 308:C 305:( 302:F 292:) 289:g 286:( 283:F 268:) 265:B 262:( 259:F 249:) 246:f 243:( 240:F 225:) 222:A 219:( 216:F 210:0 197:P 176:0 170:C 160:g 145:B 135:f 120:A 114:0 97:F 93:F 81:Q 79:β†’ 77:P 73:F 64:Q 60:P 23:.

Index

regular category
mathematics
homological algebra
functor
short exact sequences
abelian categories
covariant
additive functor
short exact sequence
topological half-exact functor
contravariant
equivalence or duality
Hom functors
category Ab of abelian groups
projective
injective
field
vector space
dual space
category of k-vector spaces
injective
module
splits
topological space
sheaves
abelian groups
ring
module
category of all left R-modules
tensor product

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

↑