cohomology

# Contents

## Definition

For a cohomology theory $E$ with cohomology groups $E(X)$ the reduced cohomology of $E$ for pointed topological spaces $X$ is on $X$ the kernel

$E_{red}(X) := ker\left(E({*} \to X) : E(X) \to E(*)\right)$

of the map $E(X) \to E({*})$ induced from the point inclusion ${*} \to X$.

Revised on October 23, 2012 20:20:44 by Urs Schreiber (131.174.191.164)