Corings, their dual rings and relative (co)Hochschild cohomology

Fuente: arXiv
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Main Author: Lindell, Jonathan
Format: Preprint
Published: 2025
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author Lindell, Jonathan
author_facet Lindell, Jonathan
contents We show for a coring which is finitely generated projective as a left module that the Cartier cohomology is isomorphic to the relative Hochschild cohomology of the right algebra. Furthermore, we show that this isomorphism lifts to the level of $B_{\infty}$-algebras of the chain complexes, by showing that the opposite $B_{\infty}$-algebra of the relative Hochschild cochains of the right algebra is isomorphic to the $B_{\infty}$-algebra of Cartier cochains. Lastly, we apply this to entwining structures where the coalgebra is finite-dimensional, to get a description of the equivariant cohomology of the entwining structure as the relative Hochschild cohomology of the twisted convolution algebra.
format Preprint
id arxiv_https___arxiv_org_abs_2508_10668
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Corings, their dual rings and relative (co)Hochschild cohomology
Lindell, Jonathan
K-Theory and Homology
Rings and Algebras
16E40 (Primary) 16T15
We show for a coring which is finitely generated projective as a left module that the Cartier cohomology is isomorphic to the relative Hochschild cohomology of the right algebra. Furthermore, we show that this isomorphism lifts to the level of $B_{\infty}$-algebras of the chain complexes, by showing that the opposite $B_{\infty}$-algebra of the relative Hochschild cochains of the right algebra is isomorphic to the $B_{\infty}$-algebra of Cartier cochains. Lastly, we apply this to entwining structures where the coalgebra is finite-dimensional, to get a description of the equivariant cohomology of the entwining structure as the relative Hochschild cohomology of the twisted convolution algebra.
title Corings, their dual rings and relative (co)Hochschild cohomology
topic K-Theory and Homology
Rings and Algebras
16E40 (Primary) 16T15
url https://arxiv.org/abs/2508.10668