Module R := R0.
Hint Resolve (@subp_sepcon _ Join_rmap Perm_rmap Sep_rmap): contractive.

Lemma ghost_fmap_fmap:  forall f1 f2 g1 g2 r,
ghost_fmap f1 f2 (ghost_fmap g1 g2 r) = ghost_fmap (f1 oo g1) (g2 oo f2) r.