A formula for the mod $p$ cohomology of $BPU(p)$

Feifei Fan

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arXiv · 2503.23399

A formula for the mod $p$ cohomology of $BPU(p)$

Feifei Fan

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Abstract

We study the mod $p$ cohomology ring of the classifying space $BPU(p)$ of the projective unitary group $PU(p)$, when $p$ is an odd prime. We prove a mod $p$ formula analogous to a formula of Vistoli for the integral cohomology ring of $BPU(p)$. As an application, we give a simple topological proof of Vistoli's formula.

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Feifei Fan. 2025-03-30. A formula for the mod $p$ cohomology of $BPU(p)$. https://arxiv.org/abs/2503.23399

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