Section Core.
(* The following definition ties together worlds and states *)
Definition hooks_consistent (c : context) (h : hooks) : Prop :=
forall z lc ls t, ((z, lc), (ls, t)) \in dom h ->
(lc \in dom c) && (ls \in dom c).
Definition hook_complete w := hooks_consistent (getc w) (geth w).

Lemma CohUn (w1 w2 : world) (s1 s2 : state) :
Coh w1 s1 -> Coh w2 s2 ->
valid (w1 \+ w2) -> Coh (w1 \+ w2) (s1 \+ s2).