Riemannian metrics on differentiable stacks
Abstract
We study Riemannian metrics on Lie groupoids in the relative setting. We show that any split fibration between proper groupoids can be made Riemannian, and we use these metrics to linearize proper groupoid fibrations. As an application, we derive rigidity theorems for Lie groupoids, which unify, simplify and improve similar results for classic geometries. Then we establish the Morita invariance for our metrics, introduce a notion for metrics on stacks, and use them to construct stacky tubular neighborhoods and to prove a stacky Ehresmann theorem.
Keywords
Cite
@article{arxiv.1601.05616,
title = {Riemannian metrics on differentiable stacks},
author = {Matias del Hoyo and Rui Loja Fernandes},
journal= {arXiv preprint arXiv:1601.05616},
year = {2019}
}
Comments
26 pages, final version. Main Theorem 4.2.3 on linearization of groupoid fibrations was strengthened. Application to deformation of foliations was removed from here and elaborated in the independent note arXiv:1807.10748