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Universal deformation rings and dihedral defect groups

Frauke M. Bleher
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Abstract

Let k be an algebraically closed field of characteristic 2, and let W be the ring of infinite Witt vectors over k. Suppose G is a finite group, and B is a block of kG with dihedral defect group D which is Morita equivalent to the principal 2-modular block of a finite simple group. We determine the universal deformation ring R(G,V) for every kG-module V which belongs to B and has stable endomorphism ring k. It follows that R(G,V) is always isomorphic to a subquotient ring of WD. Moreover, we obtain an infinite series of examples of universal deformation rings which are not complete intersections.

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BibTeXRIS

Frauke M. Bleher. 2007-05-05. Universal deformation rings and dihedral defect groups. https://doi.org/10.1090/s0002-9947-09-04543-7

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