Ricci-flat Riemannian manifold
= Ricci-flat Riemannian manifold
{c}
{title2=$\operatorname{Ric}=0$}
This is the positive-definite metric case of a <Ricci-flat manifold>.
A Ricci-flat Riemannian manifold has identically zero Ricci tensor. Every flat Riemannian manifold is Ricci-flat, while the converse can fail in dimension at least four.