(*s [(CG_standard_rho root d0 others x)] computes [d0-d] when [root] and [x] are connected by a path of minimal length [d] and [(others x)] when there are not connected *)
Definition CG_standard_rho (root : ad) (d0 : D) (others : ad -> D)
(x : ad) :=
match ad_simple_path_dist root x with
| Some d => Dplus d0 (Dneg d)
| None => others x (* dummy *)
end.

(*s If there is a root such that all the nodes ae connected to this root, then [CG_standard_rho] gives a correct valuation *)
Lemma CG_rooted_sat_1 :
forall (root : ad) (d0 : D) (others : ad -> D),
(forall x : ad, in_dom _ x cg = true -> CG_leq root x = true) ->
CGsat (CG_standard_rho root d0 others).