# 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, ...

**3**

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### Cohomological indices VS cup-length, Lusternik-Schnirelmann category, betti sum in critical point set theory

**6**

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### Generalize Wu formula to general Bockstein homomorphisms

**-2**

**1**answer

### Alternating property of H_2(T, Z)

**2**

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### A relation between Hochschild cohomology of a $C^*$ algebra and its bidual

**-1**

**1**answer

### Alternate property of H^2(T, Z) [closed]

**1**

**1**answer

### The sheafification of taking cohomology is trivial?

**37**

**0**answers

### What is Prismatic cohomology?

**2**

**1**answer

### Gysin morphism of blow up

**7**

**1**answer

### Invariants in relative cohomology and compact support cohomology of the quotient

**5**

**1**answer

### Topology of connected subsets of the $3$-torus

**4**

**0**answers

### Is the following variant of the Universal Coefficient Theorem valid?

**1**

**1**answer

### About Hom and weight space of nilpotent Lie algebra cohomology

**3**

**1**answer

### Convergence of the Lyndon-Hochschild-Serre spectral sequence as an algebra

**11**

**1**answer

### Is there an expository account of homology of simplicial sets that does not assume prior familiarity with any variant of homology?

**16**

**2**answers