(** Heaps *)
Declare Instance Join_heap: Join heap.
Declare Instance Perm_heap: Perm_alg heap.
Declare Instance Sep_heap: Sep_alg heap.
Declare Instance Canc_heap: Canc_alg heap.
Parameter rawnext: forall (x: loc) (y : val) (s : heap), Prop.
Parameter emp_at : forall (l: loc) (h: heap), Prop.

Axiom rawnext_out : forall {x x0 x' y h},
rawnext x y h -> val2loc x0 = Some x' -> x'<>x -> emp_at x' h.