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arXiv · 1707.07587

$\mathrm{H}^4(\mathrm{Co}_0;\mathbf{Z}) = \mathbf{Z}/24$

Theo Johnson-Freyd·David Treumann
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Abstract

We show that the fourth integral cohomology of Conway's group $\mathrm{Co}_0$ is a cyclic group of order $24$, generated by the first fractional Pontryagin class of the $24$-dimensional representation.

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Theo Johnson-Freyd, David Treumann. 2017-07-24. $\mathrm{H}^4(\mathrm{Co}_0;\mathbf{Z}) = \mathbf{Z}/24$. https://doi.org/10.1093/imrn/rny219

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