fact: Definition dfs1 dfs x e := let: (m1, C, e1) := dfs [set y in successors x] (visit x e) in let xC := x |: C in if m1 < serial e then (m1, xC, e1) else (#|V|, set0, store xC e1).
imports: mathcomp(all_ssreflect) bigmin extra