Retraction Theorems for Group Compactifications

Yair Hartman, Aranka Hrušková, Mehrdad Kalantar, Tomer Zimhoni

公開日: 2025/9/12

Abstract

We characterize group compactifications of discrete groups for which there exists an equivariant retraction onto the boundary. In particular, we prove an equivariant analogue of Brouwer's No-Retraction theorem for large classes of group compactifications, which includes actions of hyperbolic groups on their Gromov boundary.