Gow, Rod and Murray, John (2021) Self-dual modules in characteristic two and normal subgroups. Journal of Algebra, 570. pp. 119-139. ISSN 0021-8693
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Abstract
We prove Clifford theoretic results which only hold in
characteristic 2. Let G be a finite group, let N be a normal subgroup of G and let ϕ be an irreducible 2-Brauer character of N. We show that ϕ occurs with odd multiplicity in the restriction of some self-dual irreducible Brauer character θ of G if and only if ϕ is G-conjugate to its dual. Moreover, if ϕ is self-dual then θ is unique and the multiplicity is 1. Next suppose that θ is a self-dual irreducible 2-Brauer
character of G which is not of quadratic type. We prove
that the restriction of θ to N is a sum of distinct self-dual irreducible Brauer character of N, none of which have
quadratic type. Moreover, G has no self-dual irreducible 2-
Brauer character of non-quadratic type if and only if N and
G/N satisfy the same property. Finally, suppose that b is a real 2-block of N. We show that there is a unique real 2-block of G covering b which is weakly regular with respect to N.
| Item Type: | Article |
|---|---|
| Additional Information: | Cite as: Rod Gow, John Murray, Self-dual modules in characteristic two and normal subgroups, Journal of Algebra, Volume 570, 2021, Pages 119-139, ISSN 0021-8693, https://doi.org/10.1016/j.jalgebra.2020.11.014. |
| Keywords: | Finite groups; Representation theory; Brauer characters; Clifford theory; Duality; Quadratic modules; Brauer blocks; |
| Academic Unit: | Faculty of Science and Engineering > Mathematics and Statistics |
| Item ID: | 17955 |
| Identification Number: | 10.1016/j.jalgebra.2020.11.014 |
| Depositing User: | Dr. John Murray |
| Date Deposited: | 14 Dec 2023 13:50 |
| Journal or Publication Title: | Journal of Algebra |
| Publisher: | Elsevier |
| Refereed: | Yes |
| Related URLs: | |
| Use Licence: | This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here |
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