Definition all_assertions_computable  :=
  forall (Espec: OracleKind) psi tx vx (Q: assert), 
     exists k,  assert_safe Espec psi tx vx k = Q.

Lemma proj_frame_ret_assert: forall (R: ret_assert) (F: assert) ek vl, proj_ret_assert (frame_ret_assert R F) ek vl = seplog.sepcon (proj_ret_assert R ek vl) F.