Notation "A ==> phi" := (impl A phi) (right associativity, at level 55).Instance enumT_term : enumT term.Instance enumT_form {b} : enumT (form b).Instance dec_term : eq_dec term.Instance dec_logic : eq_dec logic.

(* Specifications: *)
Lemma dec_form {b1 b2} phi1 phi2 : dec (eq_dep logic form b1 phi1 b2 phi2).