cohomology

# Contents

## Definition

Let $C$ be a stable (∞,1)-category (or (∞,1)-topos) and $A \in C$ a stable coefficient object. For $X \in C$ and $n \in \mathbb{Z}$ or ($n \in \mathbb{N}$) write

$H^n(X,A) := \pi_0 C(X, \mathbf{B}^n A)$

for the cohomology of $X$ with coefficients in $A$ in degree $n$.

Say a morphism in $C$ is $A$-local if it induces isomorphisms on all these cohomology groups. Let $W$ be the class of all such morphisms.

Then the $A$-cohomology localization of $C$ is – if it exists – the localization of an (∞,1)-category of $C$ at $W$.

## References

Set theoretic issues in cohomology localization – and their solution using large cardinal axioms such as Vopenka's principle, is discussed in

Revised on September 3, 2012 18:09:46 by Urs Schreiber (131.174.188.82)