Homology theory

Compactly-supported homology

In mathematics, a homology theory in algebraic topology is compactly supported if, in every degree n, the relative homology group Hn(X, A) of every pair of spaces (X, A) is naturally isomorphic to the direct limit of the nth relative homology groups of pairs (Y, B), where Y varies over compact subspaces of X and B varies over compact subspaces of A. Singular homology is compactly supported, since each singular chain is a finite sum of simplices, which are compactly supported. is not compactly supported. If one has defined a homology theory over compact pairs, it is possible to extend it into a compactly supported homology theory in the wider category of Hausdorff pairs (X, A) with A closed in X, by defining that the homology of a Hausdorff pair (X, A) is the direct limit over pairs (Y, B), where Y, B are compact, Y is a subset of X, and B is a subset of A. (Wikipedia).

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From playlist Introduction to Homotopy Theory

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From playlist Mathematics

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From playlist Mathematics

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From playlist Stable Homotopy Seminar

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From playlist Vietoris-Rips Seminar

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From playlist Mathematics

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From playlist Introduction to Homotopy Theory

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From playlist Algebraic Topology

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From playlist Mathematics

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From playlist Étale cohomology and the Weil conjectures

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From playlist Mathematics

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From playlist Franco-Asian Summer School on Arithmetic Geometry (CIRM)

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From playlist Étale cohomology and the Weil conjectures

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From playlist Mathematics

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From playlist Étale cohomology and the Weil conjectures

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From playlist Étale cohomology and the Weil conjectures

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From playlist Introduction to Homotopy Theory

Related pages

Pair of spaces | Homology (mathematics) | Singular homology | Mathematics | Relative homology | Direct limit | Algebraic topology