Notation Le_AsB := (le_AsB A B leA leB).

(* Specifications: *)
Lemma acc_A_sum : forall x:A, Acc leA x -> Acc Le_AsB (inl B x).
Lemma acc_B_sum : well_founded leA -> forall x:B, Acc leB x -> Acc Le_AsB (inr A x).
Lemma wf_disjoint_sum : well_founded leA -> well_founded leB -> well_founded Le_AsB.