2 papers
math.DG2025
Geography of pinched four-manifolds
Renato G. Bettiol, Mario Kummer, Ricardo A. E. Mendes
We prove several new restrictions on the Euler characteristic and signature of oriented 4-manifolds with (positively or negatively) pinched sectional curvature. In particular, we s…
math.MG2024
A geometric take on Kostant's Convexity Theorem
Ricardo A. E. Mendes
Given a compact Lie group and an orthogonal -representation , we give a purely metric criterion for a closed subset of the orbit space to have convex pre-image in $…