fact: Parameter ac_size_unfold : forall t, ac_size t = match t with | Var _ => 1 | Term f l => (match arity f with | AC => (length l) - 1 | C => 1 | Free _ => 1 end) + list_size ac_size l end.
imports: Coq(Relations List Arith Morphisms) CoLoR(more_list list_permut list_sort term_spec term_o equational_theory_spec equational_theory)