Definition resource_fmap (f g:pred rmap -> pred rmap) (x:resource) : resource :=
    match x with
    | NO sh nsh => NO sh nsh
    | YES sh rsh k p => YES sh rsh k (preds_fmap f g p)
    | PURE k p => PURE k (preds_fmap f g p)
    end.Definition ghost_fmap (f g:pred rmap -> pred rmap)(x:ghost) : ghost :=
    map (option_map (fun '(a, b) => (a, preds_fmap f g b))) x.

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