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arXiv:0905.3121 [math.AT]AbstractReferencesReviewsResources

The computation of Stiefel-Whitney classes

Pierre Guillot

Published 2009-05-19Version 1

The cohomology ring of a finite group, with coefficients in a finite field, can be computed by a machine, as Carlson has showed. Here "compute" means to find a presentation in terms of generators and relations, and involves only the underlying (graded) ring. We propose a method to determine some of the extra structure: namely, Stiefel-Whitney classes and Steenrod operations. The calculations are explicitly carried out for about one hundred groups (the results can be consulted on the Internet). Next, we give an application: thanks to the new information gathered, we can in many cases determine which cohomology classes are supported by algebraic varieties.

Comments: To appear in Ann. Inst. Fourier
Categories: math.AT
Subjects: 20J06, 57R20, 65K05, 14C15
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