End COPY_ALT.
Section COPY_RELAT.
(* relation parent *)
Variable c0 : Config.
Variable s1 s2 : Site.
Remark copy_trans_parent :
forall s3 s4 : Site, parent (copy_trans c0 s1 s2) s4 s3 -> parent c0 s4 s3.

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