# Questions tagged [cohomology]

A branch of algebraic topology concerning the study of cocycles and coboundaries. It is in some sense a dual theory to homology theory. This tag can be further specialized by using it in conjunction with the tags group-cohomology, etale-cohomology, sheaf-cohomology, galois-cohomology, lie-algebra-cohomology, motivic-cohomology, equivariant-cohomology, ...

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### Use of Steenrod's higher cup product and the graded-commutativity

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### Non-abelian cohomologies

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### Applications of one of Serre's Theorems

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### Defining a graded ring structure on $\bigoplus_{i} \text{Ext}^i (A,A)$

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### Atiyah class and coboundary map

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### Generalized cohomology of CW complex is direct limit?

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### On the classification of $\mathrm{SU}(mn)/\mathbb{Z}_n$ principal bundles over 4-complexes

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### Lie groupoid cohomology

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### non zero differential in a spectral sequence

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### A question about Poincare duality

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### Second Bounded Cohomology of a Group: Interpretations

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### About Kan-Thurston theorem

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### Mixed Hodge Polynomial for Algebraic Stacks

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### Cohomology of a chain complex over a polynomial ring

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