English

Fractional Brauer configuration algebras II: covering theory

Representation Theory 2026-04-24 v4

Abstract

In this paper, we develop a covering theory for the fractional Brauer configurations and connect it with the coverings of the associated quivers with relations in the sense of Mart\'inez-Villa and de la Pe\~na. Among the results, we show the following: (1) The universal cover of any fractional Brauer configuration is simply connected and we construct explicitly the universal cover of fractional Brauer configurations of type MS; (2) The fundamental group of a fractional Brauer configuration EE of type S is isomorphic to the fundamental group of the associated quiver with relations (QE,IE)(Q_E,I_E); (3) A (regular) covering of fractional Brauer configurations induces a (Galois) covering of the associated fractional Brauer configuration categories; (4) Set up an analogy of Van Kampen theorem for fractional Brauer configurations and apply it to calculate the fundamental group of any connected Brauer configuration.

Keywords

Cite

@article{arxiv.2412.13445,
  title  = {Fractional Brauer configuration algebras II: covering theory},
  author = {Nengqun Li and Yuming Liu},
  journal= {arXiv preprint arXiv:2412.13445},
  year   = {2026}
}

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50 pages