X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;ds=sidebyside;f=helm%2Fsoftware%2Fmatita%2Fcontribs%2FPOPLmark%2FFsub%2Fdefn.ma;h=d9e4e4695f387c3d1f821590567f19afd21f2646;hb=f261b8315d0b14781ae78740feb476327083d664;hp=184166ed9346616940e739b222dd408a327e623b;hpb=11852aa9c64848457d84af63186d2317772e74bf;p=helm.git

diff --git a/helm/software/matita/contribs/POPLmark/Fsub/defn.ma b/helm/software/matita/contribs/POPLmark/Fsub/defn.ma
index 184166ed9..d9e4e4695 100644
--- a/helm/software/matita/contribs/POPLmark/Fsub/defn.ma
+++ b/helm/software/matita/contribs/POPLmark/Fsub/defn.ma
@@ -248,8 +248,7 @@ qed.
 
 (*** lemmata on well-formedness ***)
 
-lemma fv_WFT : \forall T,x,G.(WFType G T) \to (in_list ? x (fv_type T)) \to
-                  (in_list ? x (fv_env G)).
+lemma fv_WFT : \forall T,x,G.(WFType G T) → x ∈ fv_type T → x ∈ fv_env G.
 intros 4.elim H
   [simplify in H2;elim (in_list_cons_case ? ? ? ? H2)
      [rewrite > H3;assumption|elim (not_in_list_nil ? ? H3)]