Inductive list_incl {A} : list A -> list A -> Prop :=
| incl_nil l : list_incl [] l
| incl_skip l1 a l2 (Hincl : list_incl l1 l2) : list_incl l1 (a :: l2)
| incl_cons a l1 l2 (Hincl : list_incl l1 l2) : list_incl (a :: l1) (a :: l2).
Hint Constructors list_incl.
Inductive interleave {A} : list (list A) -> list A -> Prop :=
| interleave_nil ls (Hnil : Forall (fun l => l = []) ls) : interleave ls []
| interleave_cons ls i a l l' (Hcons : Znth i ls [] = a :: l) (Hrest : interleave (upd_Znth i ls l) l') :
interleave ls (a :: l').

Axiom ghost_conflict : forall sh1 sh2 t (v1 v2 : share * hist t) p,
ghost sh1 v1 p * ghost sh2 v2 p |-- !!sepalg.joins sh1 sh2.