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An exceptional subgroup of $\GL_2(\F_p)$ does not contain $\SL_2(\F_p)$ and is not contained in a Borel subgroup or in the normalizer of a Cartan subgroup.

Exceptional subgroups are classified according to their image in $\PGL_2(\F_p)$, which must be isomorphic to one of the alternating groups $A_4$ or $A_5$, or to the symmetric group $S_4$. These groups are labelled using identifiers containing one of the strings A4, A5, S4, as described in [arXiv:1504.07618, MR:3482279].

Knowl status:
  • Review status: reviewed
  • Last edited by Andrew Sutherland on 2021-09-18 09:45:58
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