End REC_COP1_ALT.
Section REC_COP1_RELAT.
(* relation parent *)
Variable c0 : Config.
Variable s1 s2 : Site.
Remark rcop1_trans_parent :
forall s3 s4 : Site,
parent (rec_copy1_trans c0 s1 s2) s4 s3 -> parent c0 s4 s3.

Lemma rcop1_trans_parent_cr :
forall s3 s4 : Site,
(parent c0 s3 s4 -> dt c0 s3 < dt c0 s4) ->
parent (rec_copy1_trans c0 s1 s2) s3 s4 ->
dt (rec_copy1_trans c0 s1 s2) s3 < dt (rec_copy1_trans c0 s1 s2) s4.