3 papers
math.DG2026
Proper Actions on Homogeneous Spaces of the Upper Triangular Matrix Group via Coarse Geometry
Hiroaki Nagaya
We study proper actions on homogeneous spaces of the group of invertible upper triangular matrices from a coarse-geometric viewpoint. We obtain sufficient condition…
math.CT2026
Some categorical remarks on coarse subspaces of coarse spaces
Muneto Miyaji, Hiroaki Nagaya, Kento Ogawa +1
In this paper, we provide a categorical framework for understanding coarse subspaces of coarse spaces. First, we introduce the notion of a controlled total relation between coarse…
math.DG2025
A characterization of proper actions with bornology and coarse geometry
Hiroaki Nagaya
In 1961, Palais showed that every smooth proper Lie group action on a smooth manifold admits a compatible Riemannian metric on the manifold such that the action becomes isometric.…