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arXiv · 2506.01717

On combinatorial aspects of fat Delta

Stiéphen Pradal
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Abstract

The category fat Delta, introduced by J. Kock, is a modification of the simplex category where the degeneracies behave weakly. The objective of this note is to provide tools for working with fat Delta. In particular, we identify three types of morphisms: degenerated, standard and vertical faces, and establish six relations between these classes. We then show that fat Delta is generated by these morphisms and relations.

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Stiéphen Pradal. 2025-06-02. On combinatorial aspects of fat Delta. https://arxiv.org/abs/2506.01717

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