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Intersection homology

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4580: 4231: 4262: 4929: 3903: 424:—these ideas break down. For example, it is no longer possible to make sense of the notion of "general position" for cycles. Goresky and MacPherson introduced a class of "allowable" cycles for which general position does make sense. They introduced an equivalence relation for allowable cycles (where only "allowable boundaries" are equivalent to zero), and called the group 4674: 4575:{\displaystyle {\begin{matrix}{\mathcal {H}}^{2}\left(\mathbf {R} i_{*}\mathbb {Q} _{U}|_{p=0}\right)&=&\mathbb {Q} _{p=0}\\{\mathcal {H}}^{1}\left(\mathbf {R} i_{*}\mathbb {Q} _{U}|_{p=0}\right)&=&\mathbb {Q} _{p=0}^{\oplus 2}\\{\mathcal {H}}^{0}\left(\mathbf {R} i_{*}\mathbb {Q} _{U}|_{p=0}\right)&=&\mathbb {Q} _{p=0}\end{matrix}}} 1716:. If the perversity is not specified, then one usually means the lower middle perversity. If a space can be stratified with all strata of even dimension (for example, any complex variety) then the intersection homology groups are independent of the values of the perversity on odd integers, so the upper and lower middle perversities are equivalent. 4226:{\displaystyle {\begin{aligned}H^{0}(U;\mathbb {Q} )&\cong H^{0}(X;\mathbb {Q} )=\mathbb {Q} \\H^{1}(U;\mathbb {Q} )&\cong H^{1}(X;\mathbb {Q} )=\mathbb {Q} ^{\oplus 2}\\H^{2}(U;\mathbb {Q} )&\cong H^{1}(X;\mathbb {Q} )=\mathbb {Q} ^{\oplus 2}\\H^{3}(U;\mathbb {Q} )&\cong H^{2}(X;\mathbb {Q} )=\mathbb {Q} \\\end{aligned}}} 2681: 4924:{\displaystyle {\begin{matrix}{\mathcal {H}}^{0}(IC_{\mathbb {V} (f)})&=&\mathbb {Q} _{\mathbb {V} (f)}\\{\mathcal {H}}^{1}(IC_{\mathbb {V} (f)})&=&\mathbb {Q} _{p=0}^{\oplus 2}\\{\mathcal {H}}^{i}(IC_{\mathbb {V} (f)})&=&0&{\text{for }}i\neq 0,1\end{matrix}}} 5310:. Moreover, the complex is uniquely characterized by these conditions, up to isomorphism in the derived category. The conditions do not depend on the choice of stratification, so this shows that intersection cohomology does not depend on the choice of stratification either. 3633: 237: 2460: 629: 3518: 1207: 1863: 2281: 2042:
has a triangulation compatible with the stratification, then simplicial intersection homology groups can be defined in a similar way, and are naturally isomorphic to the singular intersection homology groups.
3404: 1347: 2141:
There is a variety with two different small resolutions that have different ring structures on their cohomology, showing that there is in general no natural ring structure on intersection (co)homology.
3125: 4628: 1979:
that consists of all singular chains such that both the chain and its boundary are linear combinations of allowable singular simplexes. The singular intersection homology groups (with perversity
3908: 1464: 521:, though the groups often turn out to be independent of the choice of stratification. There are many different definitions of stratified spaces. A convenient one for intersection homology is an 2873: 814: 3003: 1105: 5276: 5182: 3274: 5103: 5019: 2676:{\displaystyle IC_{p}(X)=\tau _{\leq p(n)-n}\mathbf {R} i_{n*}\tau _{\leq p(n-1)-n}\mathbf {R} i_{n-1*}\cdots \tau _{\leq p(2)-n}\mathbf {R} i_{2*}\mathbb {C} _{X\setminus X_{n-2}}} 1006: 694: 121: 3821: 4669: 3441: 3347: 3306: 2825: 3205: 2954: 2912: 2780: 2452: 2413: 936: 3076: 1273: 3870: 3757: 422: 895: 2714: 2030: 1401: 1379: 1156: 1127: 1934: 1771: 720: 2374: 2323: 464: 2101: 1973: 1907: 1553: 287: 3467: 1668: 766: 5422: 3160: 1512: 1233: 2741: 1624: 507: 378: 330: 5451: 3682: 1050:
is any complex quasi-projective variety (possibly with singularities) then its underlying space is a topological pseudomanifold, with all strata of even dimension.
5504: 4257: 3708: 3513: 837: 3890: 3841: 3777: 3728: 3653: 3487: 3225: 3023: 1714: 547: 3352: 2130:. Roughly speaking, this means that most fibers are small. In this case the morphism induces an isomorphism from the (intersection) homology of 1164: 5476: 473:-dimensional allowable cycles modulo this equivalence relation "intersection homology". They furthermore showed that the intersection of an 1787: 2156: 63: 5602: 5533: 52: 1280: 1129:, which measures how far cycles are allowed to deviate from transversality. (The origin of the name "perversity" was explained by 5463: 3628:{\displaystyle \mathbf {R} ^{k}i_{*}\mathbb {Q} _{U}|_{p=0}=\mathop {\underset {V\subset U}{\text{colim}}} H^{k}(V;\mathbb {Q} )} 2057:
is a topological manifold, then the intersection homology groups (for any perversity) are the same as the usual homology groups.
59: 5673: 5355: 3084: 518: 344:-dimensional cycle. One may prove that the homology class of this cycle depends only on the homology classes of the original 3469:
the derived pushforward is the identity map on a smooth point, hence the only possible cohomology is concentrated in degree
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with a local system, one can use Deligne's formula to define intersection cohomology with coefficients in a local system.
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Warning: there is more than one convention for the way that the perversity enters Deligne's construction: the numbers
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The second condition is used to show invariance of intersection homology groups under change of stratification.
5581: 232:{\displaystyle H_{i}(X,\mathbb {Q} )\times H_{n-i}(X,\mathbb {Q} )\to H_{0}(X,\mathbb {Q} )\cong \mathbb {Q} .} 1062: 5217: 5123: 3230: 5047: 4963: 965: 653: 5620: 3782: 4633: 3409: 3311: 3279: 2785: 3165: 5370: 5345: 2920: 2878: 2746: 2418: 2379: 1470:
Intersection homology groups of complementary dimension and complementary perversity are dually paired.
902: 3028: 1241: 3846: 3733: 398: 848: 2689: 5360: 2326: 1989: 247: 109: 1384: 1362: 1139: 1110: 509:-dimensional allowable cycle gives an (ordinary) zero-cycle whose homology class is well-defined. 5563: 5498: 1912: 1749: 1024: 44: 2454:
and then truncating it in the derived category; more precisely it is given by Deligne's formula
699: 2340: 2289: 430: 5598: 5529: 5482: 5472: 5471:. E. Cattani, Fouad El Zein, Phillip Griffiths, DĆ©ng TrĂĄng LĂȘ., eds. Princeton. 21 July 2014. 3893: 2074: 1942: 1871: 1517: 530: 256: 243: 40: 3446: 1633: 733: 5567: 5392: 3130: 2333:(considered as an element of the derived category, so the cohomology on the right means the 1482: 1215: 333: 5588: 2719: 1568: 480: 351: 303: 5585: 5427: 5313: 3658: 2334: 534: 381: 94: 4236: 3687: 3492: 624:{\displaystyle \emptyset =X_{-1}\subset X_{0}\subset X_{1}\subset \cdots \subset X_{n}=X} 819: 5365: 3875: 3826: 3762: 3713: 3638: 3472: 3210: 3008: 2965: 82: 17: 1673: 5657: 5571: 3897: 336:, then their intersection is a finite collection of points. Using the orientation of 113: 90: 86: 67: 2046:
The intersection homology groups are independent of the choice of stratification of
340:
one may assign to each of these points a sign; in other words intersection yields a
5648: 5546: 5521: 48: 3079: 32: 3406:
This can be computed explicitly by looking at the stalks of the cohomology. At
5647:(includes discussion on the etymology of the term "intersection homology") – 5486: 5490: 102: 28: 5608: 1202:{\displaystyle \mathbf {p} \colon \mathbb {Z} _{\geq 2}\to \mathbb {Z} } 1741: 517:
Intersection homology was originally defined on suitable spaces with a
380:-dimensional cycles; one may furthermore prove that this pairing is 5644: 5550: 1858:{\displaystyle \sigma ^{-1}\left(X_{n-k}\setminus X_{n-k-1}\right)} 55:
in the fall of 1974 and developed by them over the next few years.
3730:
can be refined by considering the intersection of an open disk in
2276:{\displaystyle I^{p}H_{n-i}(X)=I^{p}H^{i}(X)=H_{c}^{i}(IC_{p}(X))} 5591:
This gives a sheaf-theoretic approach to intersection cohomology.
395:—that is, when the space has places that do not look like 3399:{\displaystyle \tau _{\leq 1}\mathbf {R} i_{*}\mathbb {Q} _{U}} 4956:
On the complement of some closed set of codimension 2, we have
1670:. Its complement is the upper middle perversity, with values 2376:
is given by starting with the constant sheaf on the open set
4844: 4763: 4685: 4609: 4592: 4477: 4371: 4273: 1342:{\displaystyle \mathbf {p} (k+1)-\mathbf {p} (k)\in \{0,1\}} 5542:
C.R. Acad. Sci. t. 284 (1977), pp. 1549–1551 Serie A .
3227:, and the derivatives are homogeneous of degree 2. Setting 2150:
Deligne's formula for intersection cohomology states that
5616:
Hist. Math. 2, Amer. Math. Soc., 1989, pp. 543–585.
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Truncating this gives the nontrivial cohomology sheaves
3120:{\displaystyle \mathbb {V} (f)\subset \mathbb {C} ^{3}} 4679: 4267: 5430: 5395: 5220: 5126: 5050: 4966: 4677: 4636: 4623:{\displaystyle {\mathcal {H}}^{0},{\mathcal {H}}^{1}} 4588: 4265: 4239: 3906: 3878: 3849: 3829: 3785: 3765: 3736: 3716: 3690: 3661: 3641: 3521: 3495: 3475: 3449: 3412: 3355: 3314: 3282: 3233: 3213: 3168: 3133: 3087: 3031: 3011: 2973: 2923: 2881: 2833: 2788: 2749: 2722: 2692: 2463: 2421: 2382: 2343: 2292: 2159: 2077: 1992: 1975:
is a subcomplex of the complex of singular chains on
1945: 1915: 1874: 1790: 1752: 1676: 1636: 1571: 1520: 1485: 1412: 1387: 1365: 1283: 1244: 1218: 1167: 1142: 1113: 1065: 968: 905: 851: 822: 778: 736: 702: 656: 550: 483: 433: 401: 354: 306: 259: 124: 3207:
vanish. This is because it is homogeneous of degree
5645:
What is the etymology of the term "perverse sheaf"?
5584:72 (1983), no. 1, 77–129. 10.1007/BF01389130 5552:
What is the etymology of the term "perverse sheaf"?
5540:
La dualité de Poincaré pour les espaces singuliers.
1459:{\displaystyle \mathbf {p} (k)+\mathbf {q} (k)=k-2} 5445: 5416: 5270: 5176: 5097: 5013: 4923: 4663: 4622: 4574: 4251: 4225: 3884: 3864: 3835: 3815: 3771: 3751: 3722: 3702: 3676: 3647: 3627: 3507: 3481: 3461: 3435: 3398: 3341: 3300: 3268: 3219: 3199: 3154: 3119: 3070: 3017: 2997: 2948: 2906: 2867: 2819: 2774: 2735: 2708: 2675: 2446: 2407: 2368: 2325:is the intersection complex, a certain complex of 2317: 2275: 2095: 2024: 1967: 1928: 1901: 1857: 1765: 1708: 1662: 1618: 1547: 1506: 1458: 1395: 1373: 1341: 1267: 1227: 1201: 1150: 1121: 1099: 1000: 930: 889: 831: 808: 760: 714: 688: 623: 501: 458: 416: 372: 324: 281: 231: 2868:{\displaystyle \mathbb {C} _{X\setminus X_{n-2}}} 2716:is a truncation functor in the derived category, 5610:The development of intersection homology theory. 5278:is zero except on a set of codimension at least 5184:is zero except on a set of codimension at least 3127:has an isolated singularity at the origin since 2415:and repeatedly extending it to larger open sets 1514:. Its complement is the maximal perversity with 809:{\displaystyle U\cong \mathbb {R} ^{i}\times CL} 5596:An Introduction to Intersection Homology Theory 246:—this duality was understood in terms of 242:Classically—going back, for instance, to 58:Intersection cohomology was used to prove the 5614:A Century of Mathematics in America, Part II, 5528:. Progress in Mathematics, Birkhauser Boston 8: 3308:the inclusion map, the intersection complex 3263: 3257: 1336: 1324: 772:, and a filtration-preserving homeomorphism 1733:with some stratification, and a perversity 1027:such that every simplex is contained in an 5503:: CS1 maint: location missing publisher ( 5037:the groups form the constant local system 4233:hence the cohomology sheaves at the stalk 3005:defined by a cubic homogeneous polynomial 2998:{\displaystyle X\subset \mathbb {CP} ^{2}} 5429: 5394: 5259: 5246: 5241: 5225: 5219: 5165: 5152: 5147: 5131: 5125: 5086: 5073: 5068: 5055: 5049: 5002: 4989: 4984: 4971: 4965: 4897: 4867: 4866: 4865: 4849: 4843: 4842: 4828: 4817: 4813: 4812: 4786: 4785: 4784: 4768: 4762: 4761: 4741: 4740: 4739: 4735: 4734: 4708: 4707: 4706: 4690: 4684: 4683: 4678: 4676: 4646: 4645: 4644: 4635: 4614: 4608: 4607: 4597: 4591: 4590: 4587: 4556: 4552: 4551: 4526: 4521: 4514: 4510: 4509: 4502: 4493: 4482: 4476: 4475: 4461: 4450: 4446: 4445: 4420: 4415: 4408: 4404: 4403: 4396: 4387: 4376: 4370: 4369: 4352: 4348: 4347: 4322: 4317: 4310: 4306: 4305: 4298: 4289: 4278: 4272: 4271: 4266: 4264: 4238: 4215: 4214: 4204: 4203: 4188: 4170: 4169: 4154: 4137: 4133: 4132: 4121: 4120: 4105: 4087: 4086: 4071: 4054: 4050: 4049: 4038: 4037: 4022: 4004: 4003: 3988: 3976: 3975: 3965: 3964: 3949: 3931: 3930: 3915: 3907: 3905: 3877: 3856: 3852: 3851: 3848: 3828: 3806: 3805: 3790: 3784: 3764: 3743: 3739: 3738: 3735: 3715: 3689: 3660: 3640: 3618: 3617: 3602: 3577: 3562: 3557: 3550: 3546: 3545: 3538: 3528: 3523: 3520: 3515:the cohomology is more interesting since 3494: 3474: 3448: 3420: 3419: 3411: 3390: 3386: 3385: 3378: 3369: 3360: 3354: 3324: 3323: 3322: 3313: 3281: 3241: 3240: 3232: 3212: 3173: 3167: 3132: 3111: 3107: 3106: 3089: 3088: 3086: 3062: 3049: 3036: 3030: 3010: 2989: 2985: 2982: 2981: 2972: 2934: 2922: 2892: 2880: 2851: 2840: 2836: 2835: 2832: 2799: 2787: 2760: 2748: 2727: 2721: 2697: 2691: 2659: 2648: 2644: 2643: 2633: 2624: 2600: 2578: 2569: 2539: 2526: 2517: 2493: 2471: 2462: 2432: 2420: 2393: 2381: 2351: 2342: 2300: 2291: 2255: 2239: 2234: 2212: 2202: 2174: 2164: 2158: 2076: 2035:are the homology groups of this complex. 2007: 1997: 1991: 1950: 1944: 1920: 1914: 1873: 1832: 1813: 1795: 1789: 1757: 1751: 1695: 1675: 1652: 1635: 1605: 1570: 1519: 1484: 1430: 1413: 1411: 1388: 1386: 1366: 1364: 1307: 1284: 1282: 1245: 1243: 1217: 1195: 1194: 1182: 1178: 1177: 1168: 1166: 1143: 1141: 1114: 1112: 1082: 1071: 1070: 1064: 1039:-simplexes, then the underlying space of 986: 973: 967: 916: 904: 875: 856: 850: 821: 791: 787: 786: 777: 735: 701: 674: 661: 655: 609: 590: 577: 561: 549: 482: 441: 432: 408: 404: 403: 400: 353: 305: 264: 258: 222: 221: 211: 210: 195: 181: 180: 159: 145: 144: 129: 123: 1100:{\displaystyle I^{\mathbf {p} }H_{i}(X)} 43:especially well-suited for the study of 5382: 5271:{\displaystyle H^{-i}(j_{x}^{!}IC_{p})} 5177:{\displaystyle H^{-i}(j_{x}^{*}IC_{p})} 3269:{\displaystyle U=\mathbb {V} (f)-\{0\}} 2927: 2885: 2844: 2792: 2753: 2652: 2425: 2386: 1825: 1130: 1035:−1 simplex is contained in exactly two 979: 909: 667: 5496: 5098:{\displaystyle H^{i}(j_{x}^{*}IC_{p})} 5014:{\displaystyle H^{i}(j_{x}^{*}IC_{p})} 1001:{\displaystyle X_{i}\setminus X_{i-1}} 689:{\displaystyle X_{i}\setminus X_{i-1}} 3816:{\displaystyle H^{k}(U;\mathbb {Q} )} 3779:, we can just compute the cohomology 950:is a topological pseudomanifold, the 7: 5538:Mark Goresky and Robert MacPherson, 4664:{\displaystyle IC_{\mathbb {V} (f)}} 3436:{\displaystyle p\in \mathbb {V} (f)} 3342:{\displaystyle IC_{\mathbb {V} (f)}} 3301:{\displaystyle i:U\hookrightarrow X} 2820:{\displaystyle X\setminus X_{n-k-1}} 5576:Goresky, Mark; MacPherson, Robert, 5558:Goresky, Mark; MacPherson, Robert, 5306:is the complementary perversity to 3200:{\displaystyle \partial _{i}f(0)=0} 2917:By replacing the constant sheaf on 108:have a fundamental property called 3170: 2949:{\displaystyle X\setminus X_{n-2}} 2907:{\displaystyle X\setminus X_{n-2}} 2775:{\displaystyle X\setminus X_{n-k}} 2447:{\displaystyle X\setminus X_{n-k}} 2408:{\displaystyle X\setminus X_{n-2}} 1917: 1754: 931:{\displaystyle X\setminus X_{n-1}} 551: 25: 5566:19 (1980), no. 2, 135–162. 4630:, hence the intersection complex 3071:{\displaystyle x^{3}+y^{3}+z^{3}} 1725:Fix a topological pseudomanifold 1268:{\displaystyle \mathbf {p} (2)=0} 1107:depend on a choice of perversity 5594:Frances Kirwan, Jonathan Woolf, 4494: 4388: 4290: 3865:{\displaystyle \mathbb {C} ^{*}} 3823:. This can be done by observing 3752:{\displaystyle \mathbb {C} ^{3}} 3524: 3370: 2625: 2570: 2518: 2134:to the intersection homology of 2126:is of codimension greater than 2 1431: 1414: 1389: 1367: 1308: 1285: 1246: 1169: 1144: 1115: 1072: 1043:is a topological pseudomanifold. 417:{\displaystyle \mathbb {R} ^{n}} 4952:) has the following properties 3872:bundle over the elliptic curve 2118:> 0, the space of points of 1777:(a singular simplex) is called 890:{\displaystyle X_{n-1}=X_{n-2}} 638:by closed subspaces such that: 5440: 5434: 5405: 5399: 5356:Topologically stratified space 5265: 5234: 5171: 5140: 5092: 5061: 5008: 4977: 4882: 4877: 4871: 4855: 4801: 4796: 4790: 4774: 4751: 4745: 4723: 4718: 4712: 4696: 4656: 4650: 4522: 4416: 4318: 4208: 4194: 4174: 4160: 4125: 4111: 4091: 4077: 4042: 4028: 4008: 3994: 3969: 3955: 3935: 3921: 3810: 3796: 3671: 3665: 3622: 3608: 3558: 3430: 3424: 3334: 3328: 3292: 3251: 3245: 3188: 3182: 3143: 3137: 3099: 3093: 2709:{\displaystyle \tau _{\leq p}} 2613: 2607: 2558: 2546: 2506: 2500: 2483: 2477: 2363: 2357: 2312: 2306: 2270: 2267: 2261: 2245: 2224: 2218: 2192: 2186: 2138:(with the middle perversity). 2122:where the fiber has dimension 2087: 2019: 2013: 1962: 1956: 1896: 1890: 1721:Singular intersection homology 1703: 1692: 1680: 1677: 1649: 1637: 1613: 1602: 1590: 1587: 1581: 1575: 1530: 1524: 1495: 1489: 1441: 1435: 1424: 1418: 1318: 1312: 1301: 1289: 1256: 1250: 1191: 1094: 1088: 768:-dimensional stratified space 755: 737: 696:, there exists a neighborhood 496: 484: 453: 447: 367: 355: 319: 307: 276: 270: 215: 201: 188: 185: 171: 149: 135: 64:Riemann–Hilbert correspondence 1: 4934:Properties of the complex IC( 2337:of the complex). The complex 2025:{\displaystyle I^{p}H_{i}(X)} 1059:Intersection homology groups 5572:10.1016/0040-9383(80)90003-8 5560:Intersection homology theory 3162:and all partial derivatives 1396:{\displaystyle \mathbf {p} } 1374:{\displaystyle \mathbf {q} } 1151:{\displaystyle \mathbf {p} } 1122:{\displaystyle \mathbf {p} } 5626:Encyclopedia of Mathematics 5336:) in the derived category. 3900:gives the cohomology groups 2067:resolution of singularities 1929:{\displaystyle \Delta ^{i}} 1766:{\displaystyle \Delta ^{i}} 1479:The minimal perversity has 77:Goresky–MacPherson approach 66:. It is closely related to 60:Kazhdan–Lusztig conjectures 5700: 1740:A map σ from the standard 1235:to the integers such that 715:{\displaystyle U\subset X} 527:topological pseudomanifold 332:-dimensional cycle are in 296:-dimensional cycle. If an 5578:Intersection homology. II 5424:are sometimes written as 2875:is the constant sheaf on 2369:{\displaystyle IC_{p}(X)} 2318:{\displaystyle IC_{p}(X)} 459:{\displaystyle IH_{i}(X)} 5582:Inventiones Mathematicae 2096:{\displaystyle f:X\to Y} 1968:{\displaystyle I^{p}(X)} 1902:{\displaystyle i-k+p(k)} 1548:{\displaystyle q(k)=k-2} 1474:Examples of perversities 1358:complementary perversity 282:{\displaystyle H_{j}(X)} 5621:"Intersection homology" 5526:Intersection Cohomology 5120: > 0 then 4671:has cohomology sheaves 3462:{\displaystyle p\neq 0} 1663:{\displaystyle (k-2)/2} 761:{\displaystyle (n-i-1)} 18:Intersection cohomology 5447: 5418: 5417:{\displaystyle p(k)-n} 5272: 5178: 5099: 5015: 4925: 4665: 4624: 4576: 4253: 4227: 3886: 3866: 3837: 3817: 3773: 3753: 3724: 3704: 3678: 3649: 3629: 3509: 3483: 3463: 3437: 3400: 3343: 3302: 3270: 3221: 3201: 3156: 3155:{\displaystyle f(0)=0} 3121: 3072: 3019: 2999: 2950: 2908: 2869: 2821: 2776: 2737: 2710: 2677: 2448: 2409: 2370: 2319: 2277: 2097: 2026: 1969: 1930: 1903: 1859: 1767: 1710: 1664: 1620: 1549: 1508: 1507:{\displaystyle p(k)=0} 1460: 1397: 1375: 1343: 1269: 1229: 1228:{\displaystyle \geq 2} 1203: 1152: 1123: 1101: 1002: 932: 891: 833: 810: 762: 716: 690: 625: 541:that has a filtration 503: 460: 418: 374: 326: 283: 233: 5674:Generalized manifolds 5507:) CS1 maint: others ( 5448: 5419: 5371:Mixed Hodge structure 5346:Decomposition theorem 5273: 5179: 5100: 5016: 4926: 4666: 4625: 4577: 4254: 4228: 3887: 3867: 3838: 3818: 3774: 3754: 3725: 3705: 3679: 3655:where the closure of 3650: 3630: 3510: 3484: 3464: 3438: 3401: 3344: 3303: 3271: 3222: 3202: 3157: 3122: 3073: 3020: 3000: 2951: 2909: 2870: 2822: 2777: 2738: 2736:{\displaystyle i_{k}} 2711: 2678: 2449: 2410: 2371: 2327:constructible sheaves 2320: 2278: 2106:of a complex variety 2098: 2027: 1970: 1931: 1904: 1860: 1768: 1711: 1665: 1621: 1619:{\displaystyle m(k)=} 1550: 1509: 1461: 1398: 1376: 1344: 1270: 1230: 1204: 1153: 1124: 1102: 1003: 933: 892: 834: 811: 763: 717: 691: 626: 504: 502:{\displaystyle (n-i)} 461: 419: 375: 373:{\displaystyle (n-i)} 327: 325:{\displaystyle (n-i)} 284: 234: 37:intersection homology 5446:{\displaystyle p(k)} 5428: 5393: 5351:Borel–Moore homology 5218: 5124: 5048: 4964: 4675: 4634: 4586: 4263: 4237: 3904: 3876: 3847: 3827: 3783: 3763: 3734: 3714: 3688: 3684:contains the origin 3677:{\displaystyle i(V)} 3659: 3639: 3519: 3493: 3473: 3447: 3410: 3353: 3312: 3280: 3231: 3211: 3166: 3131: 3085: 3029: 3009: 2971: 2921: 2879: 2831: 2786: 2747: 2743:is the inclusion of 2720: 2690: 2461: 2419: 2380: 2341: 2290: 2157: 2075: 1990: 1943: 1913: 1872: 1868:is contained in the 1788: 1750: 1674: 1634: 1569: 1518: 1483: 1410: 1385: 1363: 1281: 1242: 1216: 1165: 1140: 1111: 1063: 966: 903: 849: 839:is the open cone on 820: 776: 734: 700: 654: 548: 481: 431: 399: 352: 304: 300:-dimensional and an 292:is represented by a 257: 122: 5684:Cohomology theories 5664:Intersection theory 5361:Intersection theory 5251: 5157: 5078: 5029:≠ 0, and for 4994: 4836: 4469: 4252:{\displaystyle p=0} 3703:{\displaystyle p=0} 3508:{\displaystyle p=0} 2244: 646:and for each point 248:intersection theory 5669:Algebraic topology 5443: 5414: 5268: 5237: 5174: 5143: 5095: 5064: 5011: 4980: 4921: 4919: 4811: 4661: 4620: 4572: 4570: 4444: 4249: 4223: 4221: 3882: 3862: 3833: 3813: 3769: 3749: 3720: 3700: 3674: 3645: 3625: 3593: 3505: 3479: 3459: 3433: 3396: 3339: 3298: 3266: 3217: 3197: 3152: 3117: 3068: 3015: 2995: 2946: 2904: 2865: 2817: 2772: 2733: 2706: 2673: 2444: 2405: 2366: 2315: 2273: 2230: 2093: 2022: 1965: 1926: 1899: 1855: 1763: 1706: 1660: 1616: 1545: 1504: 1456: 1393: 1371: 1339: 1265: 1225: 1199: 1148: 1119: 1097: 1025:simplicial complex 998: 928: 887: 832:{\displaystyle CL} 829: 806: 758: 712: 686: 621: 499: 456: 414: 370: 322: 279: 229: 39:is an analogue of 5607:Kleiman, Steven. 5478:978-0-691-16134-1 5332: = dim( 5282:for the smallest 5188:for the smallest 5113: < 0 4900: 3894:hyperplane bundle 3885:{\displaystyle X} 3836:{\displaystyle U} 3772:{\displaystyle U} 3723:{\displaystyle V} 3710:. Since any such 3648:{\displaystyle V} 3581: 3578: 3482:{\displaystyle 0} 3220:{\displaystyle 3} 3018:{\displaystyle f} 2061:Small resolutions 1560:middle perversity 53:Robert MacPherson 41:singular homology 16:(Redirected from 5691: 5679:Duality theories 5634: 5555: 5514: 5512: 5502: 5494: 5489:. Archived from 5470: 5460: 5454: 5452: 5450: 5449: 5444: 5423: 5421: 5420: 5415: 5387: 5277: 5275: 5274: 5269: 5264: 5263: 5250: 5245: 5233: 5232: 5183: 5181: 5180: 5175: 5170: 5169: 5156: 5151: 5139: 5138: 5104: 5102: 5101: 5096: 5091: 5090: 5077: 5072: 5060: 5059: 5020: 5018: 5017: 5012: 5007: 5006: 4993: 4988: 4976: 4975: 4930: 4928: 4927: 4922: 4920: 4901: 4898: 4881: 4880: 4870: 4854: 4853: 4848: 4847: 4835: 4827: 4816: 4800: 4799: 4789: 4773: 4772: 4767: 4766: 4755: 4754: 4744: 4738: 4722: 4721: 4711: 4695: 4694: 4689: 4688: 4670: 4668: 4667: 4662: 4660: 4659: 4649: 4629: 4627: 4626: 4621: 4619: 4618: 4613: 4612: 4602: 4601: 4596: 4595: 4581: 4579: 4578: 4573: 4571: 4567: 4566: 4555: 4542: 4538: 4537: 4536: 4525: 4519: 4518: 4513: 4507: 4506: 4497: 4487: 4486: 4481: 4480: 4468: 4460: 4449: 4436: 4432: 4431: 4430: 4419: 4413: 4412: 4407: 4401: 4400: 4391: 4381: 4380: 4375: 4374: 4363: 4362: 4351: 4338: 4334: 4333: 4332: 4321: 4315: 4314: 4309: 4303: 4302: 4293: 4283: 4282: 4277: 4276: 4258: 4256: 4255: 4250: 4232: 4230: 4229: 4224: 4222: 4218: 4207: 4193: 4192: 4173: 4159: 4158: 4145: 4144: 4136: 4124: 4110: 4109: 4090: 4076: 4075: 4062: 4061: 4053: 4041: 4027: 4026: 4007: 3993: 3992: 3979: 3968: 3954: 3953: 3934: 3920: 3919: 3891: 3889: 3888: 3883: 3871: 3869: 3868: 3863: 3861: 3860: 3855: 3842: 3840: 3839: 3834: 3822: 3820: 3819: 3814: 3809: 3795: 3794: 3778: 3776: 3775: 3770: 3758: 3756: 3755: 3750: 3748: 3747: 3742: 3729: 3727: 3726: 3721: 3709: 3707: 3706: 3701: 3683: 3681: 3680: 3675: 3654: 3652: 3651: 3646: 3634: 3632: 3631: 3626: 3621: 3607: 3606: 3594: 3592: 3579: 3573: 3572: 3561: 3555: 3554: 3549: 3543: 3542: 3533: 3532: 3527: 3514: 3512: 3511: 3506: 3488: 3486: 3485: 3480: 3468: 3466: 3465: 3460: 3442: 3440: 3439: 3434: 3423: 3405: 3403: 3402: 3397: 3395: 3394: 3389: 3383: 3382: 3373: 3368: 3367: 3348: 3346: 3345: 3340: 3338: 3337: 3327: 3307: 3305: 3304: 3299: 3275: 3273: 3272: 3267: 3244: 3226: 3224: 3223: 3218: 3206: 3204: 3203: 3198: 3178: 3177: 3161: 3159: 3158: 3153: 3126: 3124: 3123: 3118: 3116: 3115: 3110: 3092: 3077: 3075: 3074: 3069: 3067: 3066: 3054: 3053: 3041: 3040: 3024: 3022: 3021: 3016: 3004: 3002: 3001: 2996: 2994: 2993: 2988: 2955: 2953: 2952: 2947: 2945: 2944: 2913: 2911: 2910: 2905: 2903: 2902: 2874: 2872: 2871: 2866: 2864: 2863: 2862: 2861: 2839: 2826: 2824: 2823: 2818: 2816: 2815: 2781: 2779: 2778: 2773: 2771: 2770: 2742: 2740: 2739: 2734: 2732: 2731: 2715: 2713: 2712: 2707: 2705: 2704: 2682: 2680: 2679: 2674: 2672: 2671: 2670: 2669: 2647: 2641: 2640: 2628: 2623: 2622: 2592: 2591: 2573: 2568: 2567: 2534: 2533: 2521: 2516: 2515: 2476: 2475: 2453: 2451: 2450: 2445: 2443: 2442: 2414: 2412: 2411: 2406: 2404: 2403: 2375: 2373: 2372: 2367: 2356: 2355: 2324: 2322: 2321: 2316: 2305: 2304: 2282: 2280: 2279: 2274: 2260: 2259: 2243: 2238: 2217: 2216: 2207: 2206: 2185: 2184: 2169: 2168: 2112:small resolution 2102: 2100: 2099: 2094: 2031: 2029: 2028: 2023: 2012: 2011: 2002: 2001: 1974: 1972: 1971: 1966: 1955: 1954: 1935: 1933: 1932: 1927: 1925: 1924: 1908: 1906: 1905: 1900: 1864: 1862: 1861: 1856: 1854: 1850: 1849: 1848: 1824: 1823: 1803: 1802: 1772: 1770: 1769: 1764: 1762: 1761: 1715: 1713: 1712: 1709:{\displaystyle } 1707: 1699: 1669: 1667: 1666: 1661: 1656: 1625: 1623: 1622: 1617: 1609: 1554: 1552: 1551: 1546: 1513: 1511: 1510: 1505: 1465: 1463: 1462: 1457: 1434: 1417: 1403:is the one with 1402: 1400: 1399: 1394: 1392: 1380: 1378: 1377: 1372: 1370: 1348: 1346: 1345: 1340: 1311: 1288: 1274: 1272: 1271: 1266: 1249: 1234: 1232: 1231: 1226: 1208: 1206: 1205: 1200: 1198: 1190: 1189: 1181: 1172: 1157: 1155: 1154: 1149: 1147: 1128: 1126: 1125: 1120: 1118: 1106: 1104: 1103: 1098: 1087: 1086: 1077: 1076: 1075: 1007: 1005: 1004: 999: 997: 996: 978: 977: 937: 935: 934: 929: 927: 926: 896: 894: 893: 888: 886: 885: 867: 866: 838: 836: 835: 830: 815: 813: 812: 807: 796: 795: 790: 767: 765: 764: 759: 721: 719: 718: 713: 695: 693: 692: 687: 685: 684: 666: 665: 630: 628: 627: 622: 614: 613: 595: 594: 582: 581: 569: 568: 508: 506: 505: 500: 465: 463: 462: 457: 446: 445: 423: 421: 420: 415: 413: 412: 407: 379: 377: 376: 371: 334:general position 331: 329: 328: 323: 288: 286: 285: 280: 269: 268: 250:. An element of 238: 236: 235: 230: 225: 214: 200: 199: 184: 170: 169: 148: 134: 133: 110:PoincarĂ© duality 47:, discovered by 21: 5699: 5698: 5694: 5693: 5692: 5690: 5689: 5688: 5654: 5653: 5641: 5619: 5545: 5518: 5517: 5495: 5493:on 15 Aug 2020. 5479: 5468: 5462: 5461: 5457: 5426: 5425: 5391: 5390: 5388: 5384: 5379: 5342: 5327: 5321: 5314:Verdier duality 5294:) â‰„ ( 5255: 5221: 5216: 5215: 5161: 5127: 5122: 5121: 5082: 5051: 5046: 5045: 4998: 4967: 4962: 4961: 4947: 4940: 4918: 4917: 4895: 4890: 4885: 4861: 4841: 4838: 4837: 4809: 4804: 4780: 4760: 4757: 4756: 4733: 4731: 4726: 4702: 4682: 4673: 4672: 4640: 4632: 4631: 4606: 4589: 4584: 4583: 4569: 4568: 4550: 4548: 4543: 4520: 4508: 4498: 4492: 4488: 4474: 4471: 4470: 4442: 4437: 4414: 4402: 4392: 4386: 4382: 4368: 4365: 4364: 4346: 4344: 4339: 4316: 4304: 4294: 4288: 4284: 4270: 4261: 4260: 4235: 4234: 4220: 4219: 4184: 4177: 4150: 4147: 4146: 4131: 4101: 4094: 4067: 4064: 4063: 4048: 4018: 4011: 3984: 3981: 3980: 3945: 3938: 3911: 3902: 3901: 3874: 3873: 3850: 3845: 3844: 3825: 3824: 3786: 3781: 3780: 3761: 3760: 3737: 3732: 3731: 3712: 3711: 3686: 3685: 3657: 3656: 3637: 3636: 3598: 3582: 3556: 3544: 3534: 3522: 3517: 3516: 3491: 3490: 3471: 3470: 3445: 3444: 3408: 3407: 3384: 3374: 3356: 3351: 3350: 3318: 3310: 3309: 3278: 3277: 3229: 3228: 3209: 3208: 3169: 3164: 3163: 3129: 3128: 3105: 3083: 3082: 3058: 3045: 3032: 3027: 3026: 3007: 3006: 2980: 2969: 2968: 2964:Given a smooth 2962: 2930: 2919: 2918: 2888: 2877: 2876: 2847: 2834: 2829: 2828: 2795: 2784: 2783: 2756: 2745: 2744: 2723: 2718: 2717: 2693: 2688: 2687: 2655: 2642: 2629: 2596: 2574: 2535: 2522: 2489: 2467: 2459: 2458: 2428: 2417: 2416: 2389: 2378: 2377: 2347: 2339: 2338: 2335:hypercohomology 2296: 2288: 2287: 2251: 2208: 2198: 2170: 2160: 2155: 2154: 2148: 2073: 2072: 2063: 2003: 1993: 1988: 1987: 1946: 1941: 1940: 1916: 1911: 1910: 1870: 1869: 1828: 1809: 1808: 1804: 1791: 1786: 1785: 1753: 1748: 1747: 1723: 1672: 1671: 1632: 1631: 1567: 1566: 1516: 1515: 1481: 1480: 1476: 1408: 1407: 1383: 1382: 1361: 1360: 1279: 1278: 1240: 1239: 1214: 1213: 1176: 1163: 1162: 1138: 1137: 1109: 1108: 1078: 1066: 1061: 1060: 1057: 982: 969: 964: 963: 912: 901: 900: 871: 852: 847: 846: 818: 817: 785: 774: 773: 732: 731: 698: 697: 670: 657: 652: 651: 605: 586: 573: 557: 546: 545: 515: 513:Stratifications 479: 478: 437: 429: 428: 402: 397: 396: 350: 349: 302: 301: 260: 255: 254: 191: 155: 125: 120: 119: 114:perfect pairing 83:homology groups 79: 45:singular spaces 23: 22: 15: 12: 11: 5: 5697: 5695: 5687: 5686: 5681: 5676: 5671: 5666: 5656: 5655: 5652: 5651: 5640: 5639:External links 5637: 5636: 5635: 5617: 5605: 5592: 5574: 5556: 5543: 5536: 5516: 5515: 5477: 5455: 5442: 5439: 5436: 5433: 5413: 5410: 5407: 5404: 5401: 5398: 5381: 5380: 5378: 5375: 5374: 5373: 5368: 5366:Perverse sheaf 5363: 5358: 5353: 5348: 5341: 5338: 5323: 5317: 5300: 5299: 5267: 5262: 5258: 5254: 5249: 5244: 5240: 5236: 5231: 5228: 5224: 5208: 5200:) â‰„  5173: 5168: 5164: 5160: 5155: 5150: 5146: 5142: 5137: 5134: 5130: 5114: 5094: 5089: 5085: 5081: 5076: 5071: 5067: 5063: 5058: 5054: 5042: 5041: 5010: 5005: 5001: 4997: 4992: 4987: 4983: 4979: 4974: 4970: 4958: 4957: 4943: 4942:The complex IC 4939: 4932: 4916: 4913: 4910: 4907: 4904: 4896: 4894: 4891: 4889: 4886: 4884: 4879: 4876: 4873: 4869: 4864: 4860: 4857: 4852: 4846: 4840: 4839: 4834: 4831: 4826: 4823: 4820: 4815: 4810: 4808: 4805: 4803: 4798: 4795: 4792: 4788: 4783: 4779: 4776: 4771: 4765: 4759: 4758: 4753: 4750: 4747: 4743: 4737: 4732: 4730: 4727: 4725: 4720: 4717: 4714: 4710: 4705: 4701: 4698: 4693: 4687: 4681: 4680: 4658: 4655: 4652: 4648: 4643: 4639: 4617: 4611: 4605: 4600: 4594: 4565: 4562: 4559: 4554: 4549: 4547: 4544: 4541: 4535: 4532: 4529: 4524: 4517: 4512: 4505: 4501: 4496: 4491: 4485: 4479: 4473: 4472: 4467: 4464: 4459: 4456: 4453: 4448: 4443: 4441: 4438: 4435: 4429: 4426: 4423: 4418: 4411: 4406: 4399: 4395: 4390: 4385: 4379: 4373: 4367: 4366: 4361: 4358: 4355: 4350: 4345: 4343: 4340: 4337: 4331: 4328: 4325: 4320: 4313: 4308: 4301: 4297: 4292: 4287: 4281: 4275: 4269: 4268: 4248: 4245: 4242: 4217: 4213: 4210: 4206: 4202: 4199: 4196: 4191: 4187: 4183: 4180: 4178: 4176: 4172: 4168: 4165: 4162: 4157: 4153: 4149: 4148: 4143: 4140: 4135: 4130: 4127: 4123: 4119: 4116: 4113: 4108: 4104: 4100: 4097: 4095: 4093: 4089: 4085: 4082: 4079: 4074: 4070: 4066: 4065: 4060: 4057: 4052: 4047: 4044: 4040: 4036: 4033: 4030: 4025: 4021: 4017: 4014: 4012: 4010: 4006: 4002: 3999: 3996: 3991: 3987: 3983: 3982: 3978: 3974: 3971: 3967: 3963: 3960: 3957: 3952: 3948: 3944: 3941: 3939: 3937: 3933: 3929: 3926: 3923: 3918: 3914: 3910: 3909: 3881: 3859: 3854: 3832: 3812: 3808: 3804: 3801: 3798: 3793: 3789: 3768: 3746: 3741: 3719: 3699: 3696: 3693: 3673: 3670: 3667: 3664: 3644: 3624: 3620: 3616: 3613: 3610: 3605: 3601: 3597: 3591: 3588: 3585: 3576: 3571: 3568: 3565: 3560: 3553: 3548: 3541: 3537: 3531: 3526: 3504: 3501: 3498: 3478: 3458: 3455: 3452: 3432: 3429: 3426: 3422: 3418: 3415: 3393: 3388: 3381: 3377: 3372: 3366: 3363: 3359: 3336: 3333: 3330: 3326: 3321: 3317: 3297: 3294: 3291: 3288: 3285: 3265: 3262: 3259: 3256: 3253: 3250: 3247: 3243: 3239: 3236: 3216: 3196: 3193: 3190: 3187: 3184: 3181: 3176: 3172: 3151: 3148: 3145: 3142: 3139: 3136: 3114: 3109: 3104: 3101: 3098: 3095: 3091: 3065: 3061: 3057: 3052: 3048: 3044: 3039: 3035: 3014: 2992: 2987: 2984: 2979: 2976: 2966:elliptic curve 2961: 2958: 2943: 2940: 2937: 2933: 2929: 2926: 2901: 2898: 2895: 2891: 2887: 2884: 2860: 2857: 2854: 2850: 2846: 2843: 2838: 2814: 2811: 2808: 2805: 2802: 2798: 2794: 2791: 2769: 2766: 2763: 2759: 2755: 2752: 2730: 2726: 2703: 2700: 2696: 2684: 2683: 2668: 2665: 2662: 2658: 2654: 2651: 2646: 2639: 2636: 2632: 2627: 2621: 2618: 2615: 2612: 2609: 2606: 2603: 2599: 2595: 2590: 2587: 2584: 2581: 2577: 2572: 2566: 2563: 2560: 2557: 2554: 2551: 2548: 2545: 2542: 2538: 2532: 2529: 2525: 2520: 2514: 2511: 2508: 2505: 2502: 2499: 2496: 2492: 2488: 2485: 2482: 2479: 2474: 2470: 2466: 2441: 2438: 2435: 2431: 2427: 2424: 2402: 2399: 2396: 2392: 2388: 2385: 2365: 2362: 2359: 2354: 2350: 2346: 2314: 2311: 2308: 2303: 2299: 2295: 2284: 2283: 2272: 2269: 2266: 2263: 2258: 2254: 2250: 2247: 2242: 2237: 2233: 2229: 2226: 2223: 2220: 2215: 2211: 2205: 2201: 2197: 2194: 2191: 2188: 2183: 2180: 2177: 2173: 2167: 2163: 2147: 2144: 2104: 2103: 2092: 2089: 2086: 2083: 2080: 2062: 2059: 2033: 2032: 2021: 2018: 2015: 2010: 2006: 2000: 1996: 1964: 1961: 1958: 1953: 1949: 1923: 1919: 1898: 1895: 1892: 1889: 1886: 1883: 1880: 1877: 1866: 1865: 1853: 1847: 1844: 1841: 1838: 1835: 1831: 1827: 1822: 1819: 1816: 1812: 1807: 1801: 1798: 1794: 1760: 1756: 1722: 1719: 1718: 1717: 1705: 1702: 1698: 1694: 1691: 1688: 1685: 1682: 1679: 1659: 1655: 1651: 1648: 1645: 1642: 1639: 1615: 1612: 1608: 1604: 1601: 1598: 1595: 1592: 1589: 1586: 1583: 1580: 1577: 1574: 1565:is defined by 1556: 1544: 1541: 1538: 1535: 1532: 1529: 1526: 1523: 1503: 1500: 1497: 1494: 1491: 1488: 1475: 1472: 1468: 1467: 1455: 1452: 1449: 1446: 1443: 1440: 1437: 1433: 1429: 1426: 1423: 1420: 1416: 1391: 1369: 1351: 1350: 1338: 1335: 1332: 1329: 1326: 1323: 1320: 1317: 1314: 1310: 1306: 1303: 1300: 1297: 1294: 1291: 1287: 1276: 1264: 1261: 1258: 1255: 1252: 1248: 1224: 1221: 1212:from integers 1210: 1209: 1197: 1193: 1188: 1185: 1180: 1175: 1171: 1158:is a function 1146: 1131:Goresky (2010) 1117: 1096: 1093: 1090: 1085: 1081: 1074: 1069: 1056: 1053: 1052: 1051: 1044: 995: 992: 989: 985: 981: 976: 972: 944: 943: 925: 922: 919: 915: 911: 908: 898: 884: 881: 878: 874: 870: 865: 862: 859: 855: 844: 828: 825: 805: 802: 799: 794: 789: 784: 781: 757: 754: 751: 748: 745: 742: 739: 711: 708: 705: 683: 680: 677: 673: 669: 664: 660: 632: 631: 620: 617: 612: 608: 604: 601: 598: 593: 589: 585: 580: 576: 572: 567: 564: 560: 556: 553: 519:stratification 514: 511: 498: 495: 492: 489: 486: 467: 466: 455: 452: 449: 444: 440: 436: 411: 406: 369: 366: 363: 360: 357: 321: 318: 315: 312: 309: 290: 289: 278: 275: 272: 267: 263: 244:Henri PoincarĂ© 240: 239: 228: 224: 220: 217: 213: 209: 206: 203: 198: 194: 190: 187: 183: 179: 176: 173: 168: 165: 162: 158: 154: 151: 147: 143: 140: 137: 132: 128: 78: 75: 31:, a branch of 24: 14: 13: 10: 9: 6: 4: 3: 2: 5696: 5685: 5682: 5680: 5677: 5675: 5672: 5670: 5667: 5665: 5662: 5661: 5659: 5650: 5646: 5643: 5642: 5638: 5632: 5628: 5627: 5622: 5618: 5615: 5612: 5611: 5606: 5604: 5603:1-58488-184-4 5600: 5597: 5593: 5590: 5587: 5583: 5579: 5575: 5573: 5569: 5565: 5561: 5557: 5554: 5553: 5548: 5547:Goresky, Mark 5544: 5541: 5537: 5535: 5534:0-8176-3274-3 5531: 5527: 5523: 5520: 5519: 5513:, pp. 281-282 5510: 5506: 5500: 5492: 5488: 5484: 5480: 5474: 5467: 5466: 5459: 5456: 5437: 5431: 5411: 5408: 5402: 5396: 5386: 5383: 5376: 5372: 5369: 5367: 5364: 5362: 5359: 5357: 5354: 5352: 5349: 5347: 5344: 5343: 5339: 5337: 5335: 5331: 5326: 5320: 5315: 5311: 5309: 5305: 5297: 5293: 5289: 5285: 5281: 5260: 5256: 5252: 5247: 5242: 5238: 5229: 5226: 5222: 5213: 5209: 5207: 5204: âˆ’  5203: 5199: 5195: 5191: 5187: 5166: 5162: 5158: 5153: 5148: 5144: 5135: 5132: 5128: 5119: 5115: 5112: 5109: +  5108: 5087: 5083: 5079: 5074: 5069: 5065: 5056: 5052: 5044: 5043: 5040: 5036: 5032: 5028: 5024: 5003: 4999: 4995: 4990: 4985: 4981: 4972: 4968: 4960: 4959: 4955: 4954: 4953: 4951: 4946: 4937: 4933: 4931: 4914: 4911: 4908: 4905: 4902: 4892: 4887: 4874: 4862: 4858: 4850: 4832: 4829: 4824: 4821: 4818: 4806: 4793: 4781: 4777: 4769: 4748: 4728: 4715: 4703: 4699: 4691: 4653: 4641: 4637: 4615: 4603: 4598: 4563: 4560: 4557: 4545: 4539: 4533: 4530: 4527: 4515: 4503: 4499: 4489: 4483: 4465: 4462: 4457: 4454: 4451: 4439: 4433: 4427: 4424: 4421: 4409: 4397: 4393: 4383: 4377: 4359: 4356: 4353: 4341: 4335: 4329: 4326: 4323: 4311: 4299: 4295: 4285: 4279: 4246: 4243: 4240: 4211: 4200: 4197: 4189: 4185: 4181: 4179: 4166: 4163: 4155: 4151: 4141: 4138: 4128: 4117: 4114: 4106: 4102: 4098: 4096: 4083: 4080: 4072: 4068: 4058: 4055: 4045: 4034: 4031: 4023: 4019: 4015: 4013: 4000: 3997: 3989: 3985: 3972: 3961: 3958: 3950: 3946: 3942: 3940: 3927: 3924: 3916: 3912: 3899: 3898:Wang sequence 3895: 3879: 3857: 3830: 3802: 3799: 3791: 3787: 3766: 3744: 3717: 3697: 3694: 3691: 3668: 3662: 3642: 3614: 3611: 3603: 3599: 3595: 3589: 3586: 3583: 3574: 3569: 3566: 3563: 3551: 3539: 3535: 3529: 3502: 3499: 3496: 3476: 3456: 3453: 3450: 3427: 3416: 3413: 3391: 3379: 3375: 3364: 3361: 3357: 3331: 3319: 3315: 3295: 3289: 3286: 3283: 3260: 3254: 3248: 3237: 3234: 3214: 3194: 3191: 3185: 3179: 3174: 3149: 3146: 3140: 3134: 3112: 3102: 3096: 3081: 3063: 3059: 3055: 3050: 3046: 3042: 3037: 3033: 3012: 2990: 2977: 2974: 2967: 2959: 2957: 2941: 2938: 2935: 2931: 2924: 2915: 2899: 2896: 2893: 2889: 2882: 2858: 2855: 2852: 2848: 2841: 2812: 2809: 2806: 2803: 2800: 2796: 2789: 2767: 2764: 2761: 2757: 2750: 2728: 2724: 2701: 2698: 2694: 2666: 2663: 2660: 2656: 2649: 2637: 2634: 2630: 2619: 2616: 2610: 2604: 2601: 2597: 2593: 2588: 2585: 2582: 2579: 2575: 2564: 2561: 2555: 2552: 2549: 2543: 2540: 2536: 2530: 2527: 2523: 2512: 2509: 2503: 2497: 2494: 2490: 2486: 2480: 2472: 2468: 2464: 2457: 2456: 2455: 2439: 2436: 2433: 2429: 2422: 2400: 2397: 2394: 2390: 2383: 2360: 2352: 2348: 2344: 2336: 2332: 2328: 2309: 2301: 2297: 2293: 2264: 2256: 2252: 2248: 2240: 2235: 2231: 2227: 2221: 2213: 2209: 2203: 2199: 2195: 2189: 2181: 2178: 2175: 2171: 2165: 2161: 2153: 2152: 2151: 2145: 2143: 2139: 2137: 2133: 2129: 2125: 2121: 2117: 2114:if for every 2113: 2109: 2090: 2084: 2081: 2078: 2071: 2070: 2069: 2068: 2060: 2058: 2056: 2051: 2049: 2044: 2041: 2036: 2016: 2008: 2004: 1998: 1994: 1986: 1985: 1984: 1982: 1978: 1959: 1951: 1947: 1937: 1921: 1893: 1887: 1884: 1881: 1878: 1875: 1851: 1845: 1842: 1839: 1836: 1833: 1829: 1820: 1817: 1814: 1810: 1805: 1799: 1796: 1792: 1784: 1783: 1782: 1780: 1776: 1758: 1746: 1744: 1738: 1736: 1732: 1729:of dimension 1728: 1720: 1700: 1696: 1689: 1686: 1683: 1657: 1653: 1646: 1643: 1640: 1629: 1610: 1606: 1599: 1596: 1593: 1584: 1578: 1572: 1564: 1561: 1557: 1542: 1539: 1536: 1533: 1527: 1521: 1501: 1498: 1492: 1486: 1478: 1477: 1473: 1471: 1453: 1450: 1447: 1444: 1438: 1427: 1421: 1406: 1405: 1404: 1359: 1354: 1333: 1330: 1327: 1321: 1315: 1304: 1298: 1295: 1292: 1277: 1262: 1259: 1253: 1238: 1237: 1236: 1222: 1219: 1186: 1183: 1173: 1161: 1160: 1159: 1136: 1132: 1091: 1083: 1079: 1067: 1054: 1049: 1045: 1042: 1038: 1034: 1031:-simplex and 1030: 1026: 1023:-dimensional 1022: 1018: 1014: 1013: 1012: 1009: 993: 990: 987: 983: 974: 970: 962:is the space 961: 957: 954:-dimensional 953: 949: 941: 923: 920: 917: 913: 906: 899: 882: 879: 876: 872: 868: 863: 860: 857: 853: 845: 842: 826: 823: 803: 800: 797: 792: 782: 779: 771: 752: 749: 746: 743: 740: 729: 725: 709: 706: 703: 681: 678: 675: 671: 662: 658: 649: 645: 641: 640: 639: 637: 618: 615: 610: 606: 602: 599: 596: 591: 587: 583: 578: 574: 570: 565: 562: 558: 554: 544: 543: 542: 540: 536: 532: 529:. This is a ( 528: 525:-dimensional 524: 520: 512: 510: 493: 490: 487: 476: 472: 450: 442: 438: 434: 427: 426: 425: 409: 394: 393:singularities 390: 385: 383: 364: 361: 358: 347: 343: 339: 335: 316: 313: 310: 299: 295: 273: 265: 261: 253: 252: 251: 249: 245: 226: 218: 207: 204: 196: 192: 177: 174: 166: 163: 160: 156: 152: 141: 138: 130: 126: 118: 117: 116: 115: 112:: there is a 111: 107: 104: 101:-dimensional 100: 96: 92: 88: 84: 76: 74: 72: 70: 65: 61: 56: 54: 50: 46: 42: 38: 34: 30: 19: 5649:MathOverflow 5624: 5613: 5609: 5595: 5577: 5559: 5551: 5539: 5525: 5522:Armand Borel 5491:the original 5465:Hodge Theory 5464: 5458: 5385: 5333: 5329: 5324: 5318: 5312: 5307: 5303: 5301: 5295: 5291: 5287: 5283: 5279: 5214:> 0 then 5211: 5205: 5201: 5197: 5193: 5189: 5185: 5117: 5110: 5106: 5038: 5034: 5030: 5026: 5022: 4949: 4944: 4941: 4935: 2963: 2916: 2685: 2330: 2285: 2149: 2146:Sheaf theory 2140: 2135: 2131: 2127: 2123: 2119: 2115: 2111: 2110:is called a 2107: 2105: 2064: 2054: 2052: 2047: 2045: 2039: 2037: 2034: 1980: 1976: 1939:The complex 1938: 1909:skeleton of 1867: 1778: 1774: 1742: 1739: 1734: 1730: 1726: 1724: 1628:integer part 1562: 1559: 1558:The (lower) 1469: 1357: 1355: 1352: 1211: 1134: 1058: 1055:Perversities 1047: 1040: 1036: 1032: 1028: 1020: 1016: 1010: 959: 955: 951: 947: 945: 939: 938:is dense in 840: 769: 730:, a compact 727: 723: 647: 643: 635: 633: 538: 526: 522: 516: 474: 470: 468: 392: 388: 386: 345: 341: 337: 297: 293: 291: 241: 105: 98: 80: 68: 57: 49:Mark Goresky 36: 26: 5328:shifted by 3349:is given as 3080:affine cone 531:paracompact 33:mathematics 5658:Categories 5377:References 5302:As usual, 3896:, and the 3025:, such as 1135:perversity 1011:Examples: 71:cohomology 5631:EMS Press 5499:cite book 5487:861677360 5409:− 5227:− 5154:∗ 5133:− 5105:is 0 for 5075:∗ 5021:is 0 for 4991:∗ 4906:≠ 4899:for  4830:⊕ 4504:∗ 4463:⊕ 4398:∗ 4300:∗ 4182:≅ 4139:⊕ 4099:≅ 4056:⊕ 4016:≅ 3943:≅ 3858:∗ 3596:⁡ 3587:⊂ 3540:∗ 3454:≠ 3417:∈ 3380:∗ 3362:≤ 3358:τ 3293:↪ 3255:− 3171:∂ 3103:⊂ 2978:⊂ 2939:− 2928:∖ 2897:− 2886:∖ 2856:− 2845:∖ 2810:− 2804:− 2793:∖ 2765:− 2754:∖ 2699:≤ 2695:τ 2664:− 2653:∖ 2638:∗ 2617:− 2602:≤ 2598:τ 2594:⋯ 2589:∗ 2583:− 2562:− 2553:− 2541:≤ 2537:τ 2531:∗ 2510:− 2495:≤ 2491:τ 2437:− 2426:∖ 2398:− 2387:∖ 2179:− 2088:→ 1918:Δ 1879:− 1843:− 1837:− 1826:∖ 1818:− 1797:− 1793:σ 1779:allowable 1755:Δ 1687:− 1644:− 1597:− 1540:− 1451:− 1322:∈ 1305:− 1220:≥ 1192:→ 1184:≥ 1174:: 991:− 980:∖ 921:− 910:∖ 880:− 861:− 798:× 783:≅ 750:− 744:− 707:⊂ 679:− 668:∖ 642:For each 603:⊂ 600:⋯ 597:⊂ 584:⊂ 571:⊂ 563:− 552:∅ 535:Hausdorff 491:− 477:- and an 362:− 314:− 219:≅ 189:→ 164:− 153:× 95:connected 5564:Topology 5549:(2010), 5340:See also 5316:takes IC 2960:Examples 1745:-simplex 537:) space 103:manifold 91:oriented 62:and the 29:topology 5633:, 2001 5589:0696691 956:stratum 816:. Here 382:perfect 87:compact 5601:  5532:  5485:  5475:  3892:, the 3489:. For 3443:where 3078:, the 2827:, and 2686:where 2286:where 1626:, the 1019:is an 348:- and 5469:(PDF) 5322:to IC 5286:with 5192:with 3843:is a 3759:with 3580:colim 2782:into 1133:.) A 387:When 85:of a 5599:ISBN 5530:ISBN 5509:link 5505:link 5483:OCLC 5473:ISBN 3635:for 3276:and 1356:The 391:has 81:The 51:and 5568:doi 5210:If 5116:If 5033:= − 4259:are 2329:on 2053:If 2038:If 1781:if 1773:to 1630:of 1381:of 1046:If 1015:If 958:of 946:If 726:in 722:of 650:of 634:of 469:of 27:In 5660:: 5629:, 5623:, 5586:MR 5580:, 5562:, 5524:, 5501:}} 5497:{{ 5481:. 5025:+ 2914:. 2065:A 2050:. 1983:) 1936:. 1737:. 1008:. 533:, 384:. 97:, 93:, 89:, 73:. 35:, 5570:: 5511:) 5453:. 5441:) 5438:k 5435:( 5432:p 5412:n 5406:) 5403:k 5400:( 5397:p 5334:X 5330:n 5325:q 5319:p 5308:p 5304:q 5298:) 5296:i 5292:a 5290:( 5288:q 5284:a 5280:a 5266:) 5261:p 5257:C 5253:I 5248:! 5243:x 5239:j 5235:( 5230:i 5223:H 5212:i 5206:i 5202:m 5198:a 5196:( 5194:p 5190:a 5186:a 5172:) 5167:p 5163:C 5159:I 5149:x 5145:j 5141:( 5136:i 5129:H 5118:i 5111:m 5107:i 5093:) 5088:p 5084:C 5080:I 5070:x 5066:j 5062:( 5057:i 5053:H 5039:C 5035:m 5031:i 5027:m 5023:i 5009:) 5004:p 5000:C 4996:I 4986:x 4982:j 4978:( 4973:i 4969:H 4950:X 4948:( 4945:p 4938:) 4936:X 4915:1 4912:, 4909:0 4903:i 4893:0 4888:= 4883:) 4878:) 4875:f 4872:( 4868:V 4863:C 4859:I 4856:( 4851:i 4845:H 4833:2 4825:0 4822:= 4819:p 4814:Q 4807:= 4802:) 4797:) 4794:f 4791:( 4787:V 4782:C 4778:I 4775:( 4770:1 4764:H 4752:) 4749:f 4746:( 4742:V 4736:Q 4729:= 4724:) 4719:) 4716:f 4713:( 4709:V 4704:C 4700:I 4697:( 4692:0 4686:H 4657:) 4654:f 4651:( 4647:V 4642:C 4638:I 4616:1 4610:H 4604:, 4599:0 4593:H 4564:0 4561:= 4558:p 4553:Q 4546:= 4540:) 4534:0 4531:= 4528:p 4523:| 4516:U 4511:Q 4500:i 4495:R 4490:( 4484:0 4478:H 4466:2 4458:0 4455:= 4452:p 4447:Q 4440:= 4434:) 4428:0 4425:= 4422:p 4417:| 4410:U 4405:Q 4394:i 4389:R 4384:( 4378:1 4372:H 4360:0 4357:= 4354:p 4349:Q 4342:= 4336:) 4330:0 4327:= 4324:p 4319:| 4312:U 4307:Q 4296:i 4291:R 4286:( 4280:2 4274:H 4247:0 4244:= 4241:p 4216:Q 4212:= 4209:) 4205:Q 4201:; 4198:X 4195:( 4190:2 4186:H 4175:) 4171:Q 4167:; 4164:U 4161:( 4156:3 4152:H 4142:2 4134:Q 4129:= 4126:) 4122:Q 4118:; 4115:X 4112:( 4107:1 4103:H 4092:) 4088:Q 4084:; 4081:U 4078:( 4073:2 4069:H 4059:2 4051:Q 4046:= 4043:) 4039:Q 4035:; 4032:X 4029:( 4024:1 4020:H 4009:) 4005:Q 4001:; 3998:U 3995:( 3990:1 3986:H 3977:Q 3973:= 3970:) 3966:Q 3962:; 3959:X 3956:( 3951:0 3947:H 3936:) 3932:Q 3928:; 3925:U 3922:( 3917:0 3913:H 3880:X 3853:C 3831:U 3811:) 3807:Q 3803:; 3800:U 3797:( 3792:k 3788:H 3767:U 3745:3 3740:C 3718:V 3698:0 3695:= 3692:p 3672:) 3669:V 3666:( 3663:i 3643:V 3623:) 3619:Q 3615:; 3612:V 3609:( 3604:k 3600:H 3590:U 3584:V 3575:= 3570:0 3567:= 3564:p 3559:| 3552:U 3547:Q 3536:i 3530:k 3525:R 3503:0 3500:= 3497:p 3477:0 3457:0 3451:p 3431:) 3428:f 3425:( 3421:V 3414:p 3392:U 3387:Q 3376:i 3371:R 3365:1 3335:) 3332:f 3329:( 3325:V 3320:C 3316:I 3296:X 3290:U 3287:: 3284:i 3264:} 3261:0 3258:{ 3252:) 3249:f 3246:( 3242:V 3238:= 3235:U 3215:3 3195:0 3192:= 3189:) 3186:0 3183:( 3180:f 3175:i 3150:0 3147:= 3144:) 3141:0 3138:( 3135:f 3113:3 3108:C 3100:) 3097:f 3094:( 3090:V 3064:3 3060:z 3056:+ 3051:3 3047:y 3043:+ 3038:3 3034:x 3013:f 2991:2 2986:P 2983:C 2975:X 2942:2 2936:n 2932:X 2925:X 2900:2 2894:n 2890:X 2883:X 2859:2 2853:n 2849:X 2842:X 2837:C 2813:1 2807:k 2801:n 2797:X 2790:X 2768:k 2762:n 2758:X 2751:X 2729:k 2725:i 2702:p 2667:2 2661:n 2657:X 2650:X 2645:C 2635:2 2631:i 2626:R 2620:n 2614:) 2611:2 2608:( 2605:p 2586:1 2580:n 2576:i 2571:R 2565:n 2559:) 2556:1 2550:n 2547:( 2544:p 2528:n 2524:i 2519:R 2513:n 2507:) 2504:n 2501:( 2498:p 2487:= 2484:) 2481:X 2478:( 2473:p 2469:C 2465:I 2440:k 2434:n 2430:X 2423:X 2401:2 2395:n 2391:X 2384:X 2364:) 2361:X 2358:( 2353:p 2349:C 2345:I 2331:X 2313:) 2310:X 2307:( 2302:p 2298:C 2294:I 2271:) 2268:) 2265:X 2262:( 2257:p 2253:C 2249:I 2246:( 2241:i 2236:c 2232:H 2228:= 2225:) 2222:X 2219:( 2214:i 2210:H 2204:p 2200:I 2196:= 2193:) 2190:X 2187:( 2182:i 2176:n 2172:H 2166:p 2162:I 2136:Y 2132:X 2128:r 2124:r 2120:Y 2116:r 2108:Y 2091:Y 2085:X 2082:: 2079:f 2055:X 2048:X 2040:X 2020:) 2017:X 2014:( 2009:i 2005:H 1999:p 1995:I 1981:p 1977:X 1963:) 1960:X 1957:( 1952:p 1948:I 1922:i 1897:) 1894:k 1891:( 1888:p 1885:+ 1882:k 1876:i 1852:) 1846:1 1840:k 1834:n 1830:X 1821:k 1815:n 1811:X 1806:( 1800:1 1775:X 1759:i 1743:i 1735:p 1731:n 1727:X 1704:] 1701:2 1697:/ 1693:) 1690:1 1684:k 1681:( 1678:[ 1658:2 1654:/ 1650:) 1647:2 1641:k 1638:( 1614:] 1611:2 1607:/ 1603:) 1600:2 1594:k 1591:( 1588:[ 1585:= 1582:) 1579:k 1576:( 1573:m 1563:m 1555:. 1543:2 1537:k 1534:= 1531:) 1528:k 1525:( 1522:q 1502:0 1499:= 1496:) 1493:k 1490:( 1487:p 1466:. 1454:2 1448:k 1445:= 1442:) 1439:k 1436:( 1432:q 1428:+ 1425:) 1422:k 1419:( 1415:p 1390:p 1368:q 1349:. 1337:} 1334:1 1331:, 1328:0 1325:{ 1319:) 1316:k 1313:( 1309:p 1302:) 1299:1 1296:+ 1293:k 1290:( 1286:p 1275:. 1263:0 1260:= 1257:) 1254:2 1251:( 1247:p 1223:2 1196:Z 1187:2 1179:Z 1170:p 1145:p 1116:p 1095:) 1092:X 1089:( 1084:i 1080:H 1073:p 1068:I 1048:X 1041:X 1037:n 1033:n 1029:n 1021:n 1017:X 994:1 988:i 984:X 975:i 971:X 960:X 952:i 948:X 942:. 940:X 924:1 918:n 914:X 907:X 897:. 883:2 877:n 873:X 869:= 864:1 858:n 854:X 843:. 841:L 827:L 824:C 804:L 801:C 793:i 788:R 780:U 770:L 756:) 753:1 747:i 741:n 738:( 728:X 724:x 710:X 704:U 682:1 676:i 672:X 663:i 659:X 648:x 644:i 636:X 619:X 616:= 611:n 607:X 592:1 588:X 579:0 575:X 566:1 559:X 555:= 539:X 523:n 497:) 494:i 488:n 485:( 475:i 471:i 454:) 451:X 448:( 443:i 439:H 435:I 410:n 405:R 389:X 368:) 365:i 359:n 356:( 346:i 342:0 338:X 320:) 317:i 311:n 308:( 298:i 294:j 277:) 274:X 271:( 266:j 262:H 227:. 223:Q 216:) 212:Q 208:, 205:X 202:( 197:0 193:H 186:) 182:Q 178:, 175:X 172:( 167:i 161:n 157:H 150:) 146:Q 142:, 139:X 136:( 131:i 127:H 106:X 99:n 69:L 20:)

Index

Intersection cohomology
topology
mathematics
singular homology
singular spaces
Mark Goresky
Robert MacPherson
Kazhdan–Lusztig conjectures
Riemann–Hilbert correspondence
L cohomology
homology groups
compact
oriented
connected
manifold
Poincaré duality
perfect pairing
Henri Poincaré
intersection theory
general position
perfect
stratification
paracompact
Hausdorff
simplicial complex
Goresky (2010)
integer part
i-simplex
resolution of singularities
constructible sheaves

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