Bredon cohomology of finite dimensional $C_p$-spaces

TL;DR

This paper computes the Bredon cohomology of finite dimensional free $C_p$-spaces with constant coefficients, leading to applications in equivariant topology and non-existence results for certain $C_p$-maps.

Contribution

It provides explicit calculations of Bredon cohomology rings for finite dimensional $C_p$-spaces, including those built from representations, and applies these to topological theorems.

Findings

Cohomology ring calculations for free $C_p$-spaces.

Proofs of non-existence of certain $C_p$-maps.

Cohomology of representation-based $C_p$-spaces is free over a point.

Abstract

For finite dimensional free $C_p$-spaces, the calculation of the Bredon cohomology ring as an algebra over the cohomology of $S^0$ is used to prove the non-existence of certain $C_p$-maps. These are related to Borsuk-Ulam type theorems, and equivariant maps related to the topological Tverberg conjecture. For certain finite dimensional $C_p$-spaces which are formed out of representations, it is proved that the cohomology is a free module over the cohomology of a point. All the calculations are done for the cohomology with constant coefficients $\mathbb{Z}/p$.