fact: Definition kolmogorov_space := forall x y, x != y -> exists A : set T, (A \in nbhs x /\ y \in ~` A) \/ (A \in nbhs y /\ x \in ~` A).
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed