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arXiv · 2604.15142

Invertibility and parity in symmetric monoidal categories

Abstract

We introduce a notion of parity for formal morphisms between invertible objects and use it to prove a corresponding coherence theorem. Parity is conceptually similar to the sign of underlying permutations, but not defined as such. To give complete details, this work includes a thorough treatment of the free permutative category on an invertible generator, its skeletal model, known as the super integers, and an equivalence between them classified by the pair of integers $\pm$1. Our approach is organized and clarified as an application of 2-monadic algebra, particularly the concept of flexibility and the Lack model structure. The final section contains a number of examples applying the main results.

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BibTeXRIS

Nick Gurski, Niles Johnson. 2026-04-16. Invertibility and parity in symmetric monoidal categories. https://arxiv.org/abs/2604.15142

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