fact: Definition limit_of (f: Tf) x := [/\ (forall n m, (n < m)%N -> f n < f m), (forall n, f n < x) & (forall y, T3nf y -> y < x -> (exists n, y <= f n))].
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(fintype bigop)