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reduced cohomology

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Definition

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

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

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

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