Instance unit_PCM : Ghost := { valid a := True; Join_G a b c := True }.Definition pred_of (P : mpred) := SomeP rmaps.Mpred (fun _ => P).Definition agree g (P : mpred) := own(RA := unit_PCM) g tt (pred_of P).

Lemma agree_dup : forall g P, agree g P = agree g P * agree g P.