Section protocols.
Context {state : Type}.
Parameter protocol_piece : share -> val -> state -> (state -> state -> Prop) ->
((state -> Z -> mpred) * (state -> Z -> mpred)) -> mpred.
Definition protocol_R := protocol_piece Share.bot.
Definition protocol_W := protocol_piece gsh2.
Context (ord : state -> state -> Prop) `{RelationClasses.PreOrder _ ord}
(Tread Tfull : state -> Z -> mpred).
Notation T := (Tread, Tfull).

Axiom protocol_R_join' : forall l s1 s2,
protocol_R l s1 ord T * protocol_R l s2 ord T |--
EX s : _, !!(ord s1 s /\ ord s2 s) && protocol_R l s ord T.