Section MESSAGE.
(* as formulated by Jean *)
(* As I need it in my proof *)
(* The proof is long and very boring, but it is a simple case analysis.  Could it be possible to simplify it? *)

Lemma st_rt :
forall (c0 : Config) (s0 : Site),
legal c0 -> s0 <> owner -> (st c0 s0 > 0)%Z -> rt c0 s0 = true.