A pseudo-Riemannian manifold is a manifold which has a metric that is of the signature , as compared to a Riemannian manifold, which has a signature of all positive signs.
Pseudo-Riemannian Manifold
See also
Campbell's Theorem, Minkowski Metric, Minkowski Space, Riemannian ManifoldExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Pseudo-Riemannian Manifold." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Pseudo-RiemannianManifold.html