Time-like isothermic surfaces associated to Grassmannian systems

Abstract

We establish that, as is the case with space-like isothermic surfaces, time-like isothermic surfaces in pseudo-riemannian space ${\mathbb{R}}^{n-j,j}$ are associated to the $O(n-j+1,j+1)/O(n-j,j)\times O(1,1)$-system.