# Brackets and products from centres in extension categories

@inproceedings{Fiorenza2021BracketsAP, title={Brackets and products from centres in extension categories}, author={Domenico Fiorenza and Niels Kowalzig}, year={2021} }

Building on Retakh’s approach to Ext groups through categories of extensions, Schwede reobtained the well-known Gerstenhaber algebra structure on Ext groups over bimodules of associative algebras both from splicing extensions (leading to the cup product) and from a suitable loop in the categories of extensions (leading to the Lie bracket). We show how Schwede’s construction admits a vast generalisation to general monoidal categories with coefficients of the Ext groups taken in (weak) left and…

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