Definition all_assertions_computable  :=
forall (Espec: OracleKind) psi tx vx (Q: assert),
exists k,  assert_safe Espec psi tx vx k = Q.
(* This is not generally true, but could be made true by adding an "assert" operator to the programming language *)

Lemma ewand_TT_emp {A} {JA: Join A}{PA: Perm_alg A}{SA: Sep_alg A}{CA: Canc_alg A}:
ewand TT emp = emp.