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Cotensor products of modules

Lowell Abrams·Charles Weibel
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Abstract

Let C be a coalgebra over a field k and A its dual algebra. The category of C-comodules is equivalent to a category of A-modules. We use this to interpret the cotensor product M \square N of two comodules in terms of the appropriate Hochschild cohomology of the A-bimodule M \otimes N, when A is finite-dimensional, profinite, graded or differential-graded. The main applications are to Galois cohomology, comodules over the Steenrod algebra, and the homology of induced fibrations.

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Lowell Abrams, Charles Weibel. 1999-12-27. Cotensor products of modules. https://arxiv.org/abs/math/9912211

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