Definition rmap' := ((address -> resource) * ghost)%type.
Definition rmap_fmap (f g: pred rmap -> pred rmap) (x:rmap') : rmap' :=
(resource_fmap f g oo fst x, ghost_fmap f g (snd x)).

Axiom rmap_fmap_id : rmap_fmap (id _) (id _) = id rmap'.