Urysohn 1-width for 4 and 5 manifolds with positive biRicci curvature

Abstract

It was proved by Gromov-Lawson\cite{gl83} that complete three manifold with positive scalar curvature bounded below has finite Urysohn 1-width only depends on the uniform positive scalar curvature bounds. It is natural to ask the same question for the four manifolds. In this paper, we can show that closed four and five manifolds with positive biRicci curvature has finite Urysohn 1-width only depends on the curvature bounds. During the proof we can also observe that the fundamental group of those manifolds are virtually free. This gives a quick application that $T^{2}\times S^{2}$ can't admit positive biRicci curvature.