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arXiv · 2605.22969

Real 2-blocks in quasi-simple groups

John Revere McHugh·A. A. Schaeffer Fry
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Abstract

We determine which quasi-simple groups have a non-principal $2$-block that is stable under complex conjugation. As a corollary, we determine that the Mathieu group $M_{22}$ is the only simple group not possessing a nontrivial irreducible Brauer character of quadratic type, answering a recent question of Gow and Murray.

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John Revere McHugh, A. A. Schaeffer Fry. 2026-05-21. Real 2-blocks in quasi-simple groups. https://arxiv.org/abs/2605.22969

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