On Tensor Products of Simple Modules for Simple Groups, Errata

David A. Craven, University of Birmingham

5th May, 2021

I distinguish four types of corrections, in order of increasing seriousness:

  • (Extra) Additional information that was not available at the time of writing, or that I did not know about.

  • (Improve) Typographical issues, where what is written is still correct, but there is a nicer way of phrasing it, or I could choose a better symbol.

  • (Typo) Typographical errors, where I have spelled a word wrongly, used the wrong symbol, and so on.

  • (Error) Errors in proofs or statements.

When I give each correction, I will label it with one of these monikers.

  • (i) (Error) p.388, just after Proposition 4.7. We do not, in fact, see that all simple modules are algebraic for \(p=2\) for \(\mathfrak {S}_6\) in Theorem 7.3. It is true though, as an easy computer check proves.

    Thanks to Daniel Tubbenhauer for pointing this out.

  • (ii) (Error) p.388, last paragraph of the section. \(\mathrm {SU}_4(2)\) does not embed in \(\mathrm {SU}_4(2^a)\) for \(a\) even, so this does not prove the result for \(q\) even. While I’m absolutely sure that the statement is true for \(q\) a power of \(4\), I have no proof at the moment.