Cotton tensor
rank-3 tensor defined for a 3d (pseudo-)Riemannian manifold which measures the degree to which it fails to be conformally flat
en-GB/ˈkɒtən ˈtɛnsə/
en-US/ˈkɔdən ˈtɛnsɚ/
rank-3 tensor defined for a 3d (pseudo-)Riemannian manifold which measures the degree to which it fails to be conformally flat