Universal construction in monoidal and non-monoidal settings, the Brauer envelope, and pseudocharacters

Mee Seong Im ; Mikhail Khovanov ; Victor Ostrik

Theory and applications of categories, Tome 44 (2025), pp. 15-83.

Résumé

This paper clarifies basic definitions in the universal construction of topological theories and monoidal categories. The definition of the universal construction is given for various types of monoidal categories, including rigid and symmetric. It is also explained how to set up the universal construction for non-monoidal categories. The second part of the paper explains how to associate a rigid symmetric monoidal category to a small category, a sort of the Brauer envelope of a category. The universal construction for the Brauer envelopes generalizes some earlier work of the first two authors on automata, power series and topological theories. Finally, the theory of pseudocharacters (or pseudo-representations), which is an essential tool in modern number theory, is interpreted via one-dimensional topological theories and TQFTs with defects. The notion of a pseudocharacter is studied for the Brauer categories and the lifting property to characters of semisimple representations is established in characteristic 0 for the Brauer categories with at most countably many objects. The paper contains a brief discussion of pseudo-holonomies, which are functions from loops in a manifold to real numbers similar to traces of the holonomies along loops of a connection on a vector bundle on the manifold. It concludes with a classification of pseudocharacters (pseudo-TQFTs) and their generating functions for the category of oriented two-dimensional cobordisms in the characteristic 0 case.

Détail

Publié le : 2025-01-08

Classification : Primary: 57K16, 18M05, 18M30, Secondary: 15A15
Keywords: Topological theory, topological quantum field theory, TQFT, defects, universal construction, pseudocharacter, pseudo-TQFT, Brauer envelope