A gap theorem for Ricci-flat 4-manifolds

Atreyee Bhattacharya, Harish Seshadri

Let $(M,g)$ be a compact Ricci-flat 4-manifold. For $p\in M$ let $K_{max}(p)$ (respectively $K_{min}(p)$) denote the maximum (respectively the minimum) of sectional curvatures at…