English

Bousfield-Segal spaces

Algebraic Topology 2021-03-17 v2 Category Theory

Abstract

This paper is a study of Bousfield-Segal spaces, a notion introduced by Julie Bergner drawing on ideas about Eilenberg-Mac Lane objects due to Bousfield. In analogy to Rezk's Segal spaces, they are defined in such a way that Bousfield-Segal spaces naturally come equipped with a homotopy-coherent fraction operation in place of a composition. In this paper we show that Bergner's model structure for Bousfield-Segal spaces in fact can be obtained from the model structure for Segal spaces both as a localization and a colocalization. We thereby prove that Bousfield-Segal spaces really are Segal spaces, and that they characterize exactly those with invertible arrows. We note that the complete Bousfield-Segal spaces are precisely the homotopically constant Segal spaces, and deduce that the associated model structure yields a model for both \infty-groupoids and Homotopy Type Theory.

Cite

@article{arxiv.1911.02454,
  title  = {Bousfield-Segal spaces},
  author = {Raffael Stenzel},
  journal= {arXiv preprint arXiv:1911.02454},
  year   = {2021}
}

Comments

On advice of an anonymous referee, restructured large parts of the paper for better readibility and corrected a few minor errors. We give a considerably shorter and more conceptual proof of the fact that Bousfield-Segal spaces are Segal spaces. Added a proof that the core construction for Segal spaces is part of a colocalization. Accepted for publication in Homology, Homotopy and Applications

R2 v1 2026-06-23T12:07:33.730Z