On the closure of the diagonal of a T-1-space
Let X be a topological space. The closure of Delta = {(x,x) : x epsilon X} in X x X is a symmetric relation on X. We characterise those equivalence relations on an infinite set that arise as the closure of the diagonal with respect to a T-1-topology. (C) 2008 Elsevier Inc. All rights reserved.
diagonal t-1-space topological space equivalence relation separation