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Homotopy formulas for cyclic groups acting on rings

Christian Kassel
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Abstract

The positive cohomology groups of a finite group acting on a ring vanish when the ring has a norm-one element. In this note we give explicit homotopies on the level of cochains when the group is cyclic, which allows us to express any cocycle of a cyclic group as the coboundary of an explicit cochain. The formulas in this note are closely related to the effective problems considered in previous joint work with Eli Aljadeff.

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Christian Kassel. 2005-10-11. Homotopy formulas for cyclic groups acting on rings. https://arxiv.org/abs/math/0510222

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