Instance Perm_combiner : Perm_alg combiner.
Instance Sep_combiner: Sep_alg combiner.
Instance Disj_combiner {D1: Disj_alg A}: Disj_alg combiner.
(* Usefull facts about combiners *)

(* Specifications: *)
Lemma identity_combiner {C1: Canc_alg T1}: forall d : combiner,
identity d ->
d = CEmpty.
Lemma combiner_identity {C1: Canc_alg T1}:
identity CEmpty.
Lemma combiner_full {C1: Canc_alg T1}: forall t2,
full (CFull t2).