fact: Definition ncvg u l := forall v : nbh l, exists K, forall n, (K <= n)%N -> u n \in v.
imports: mathcomp(all_ssreflect all_algebra) mathcomp.bigenough.bigenough mathcomp.classical(boolp classical_sets functions) mathcomp.classical(mathcomp_extra) xfinmap ereal reals discrete topology