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arXiv · 2205.15297

Exact subcategories, subfunctors of $\operatorname{Ext}$, and some applications

Hailong Dao·Souvik Dey·Monalisa Dutta
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Abstract

Let $(\mathcal{A},\mathcal{E})$ be an exact category. We establish basic results that allow one to identify sub(bi)functors of $\operatorname{Ext}_{\mathcal{E}}(-,-)$ using additivity of numerical functions and restriction to subcategories. We also study a small number of these new functors over commutative local rings in details, and find a range of applications from detecting regularity to understanding Ulrich modules.

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Hailong Dao, Souvik Dey, Monalisa Dutta. 2022-05-27. Exact subcategories, subfunctors of $\operatorname{Ext}$, and some applications. https://doi.org/10.1017/nmj.2023.29

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