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Restriction of projective group representations to subgroups and centralizers. (English) Zbl 0785.20009
From the introduction: “Projective representations of a group are homomorphisms into projective linear groups. In this paper we relate projective representations of a finite group $$G$$ over a connected commutative ring $$R$$ to projective representations of an arbitrary subgroup $$H$$ of $$G$$ (not necessarily normal in $$G$$). Obviously projective representations of $$G$$ over $$R$$ correspond to modules over twisted group rings $$R*_ \alpha G$$, $$\alpha$$ being a 2-cocycle. We concentrate on the separable case, that is, $$| G|^{-1}\in R$$”.

##### MSC:
 20C25 Projective representations and multipliers
##### Keywords:
projective representations; twisted group rings
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