X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fbasic_2%2Frelocation%2Flifts_lifts.ma;h=3822e2dd0ab1146121c1125fc8c691e716ac54f5;hb=1fd62f1ce4f8209dec780d80aa53b140a8882ad7;hp=2d00bcbc25f3c81330cb0c5d543a7c99f6987ed6;hpb=d64b4238ec803353f0a06f2aad25c173852b0526;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/basic_2/relocation/lifts_lifts.ma b/matita/matita/contribs/lambdadelta/basic_2/relocation/lifts_lifts.ma
index 2d00bcbc2..3822e2dd0 100644
--- a/matita/matita/contribs/lambdadelta/basic_2/relocation/lifts_lifts.ma
+++ b/matita/matita/contribs/lambdadelta/basic_2/relocation/lifts_lifts.ma
@@ -20,9 +20,9 @@ include "basic_2/relocation/lifts.ma".
 
 (* Basic_1: includes: lift_gen_lift *)
 (* Basic_2A1: includes: lift_div_le lift_div_be *)
-theorem lift_div4: ∀f2,Tf,T. ⬆*[f2] Tf ≡ T → ∀g2,Tg. ⬆*[g2] Tg ≡ T →
-                   ∀f1,g1. H_at_div f2 g2 f1 g1 →
-                   ∃∃T0. ⬆*[f1] T0 ≡ Tf & ⬆*[g1] T0 ≡ Tg.
+theorem lifts_div4: ∀f2,Tf,T. ⬆*[f2] Tf ≡ T → ∀g2,Tg. ⬆*[g2] Tg ≡ T →
+                    ∀f1,g1. H_at_div f2 g2 f1 g1 →
+                    ∃∃T0. ⬆*[f1] T0 ≡ Tf & ⬆*[g1] T0 ≡ Tg.
 #f2 #Tf #T #H elim H -f2 -Tf -T
 [ #f2 #s #g2 #Tg #H #f1 #g1 #_
   lapply (lifts_inv_sort2 … H) -H #H destruct
@@ -49,7 +49,7 @@ qed-.
 lemma lifts_div4_one: ∀f,Tf,T. ⬆*[↑f] Tf ≡ T →
                       ∀T1. ⬆*[1] T1 ≡ T →
                       ∃∃T0. ⬆*[1] T0 ≡ Tf & ⬆*[f] T0 ≡ T1.
-/4 width=6 by lift_div4, at_div_id_dx, at_div_pn/ qed-.
+/4 width=6 by lifts_div4, at_div_id_dx, at_div_pn/ qed-.
 
 theorem lifts_div3: ∀f2,T,T2. ⬆*[f2] T2 ≡ T → ∀f,T1. ⬆*[f] T1 ≡ T →
                     ∀f1. f2 ⊚ f1 ≡ f → ⬆*[f1] T1 ≡ T2.
@@ -106,13 +106,25 @@ qed-.
 (* Advanced proprerties *****************************************************)
 
 (* Basic_2A1: includes: lift_inj *)
-lemma lifts_inj: ∀f,T1,U. ⬆*[f] T1 ≡ U → ∀T2. ⬆*[f] T2 ≡ U → T1 = T2.
+lemma lifts_inj: ∀f. is_inj2 … (lifts f).
 #f #T1 #U #H1 #T2 #H2 lapply (after_isid_dx 𝐈𝐝  … f)
 /3 width=6 by lifts_div3, lifts_fwd_isid/
 qed-.
 
 (* Basic_2A1: includes: lift_mono *)
-lemma lifts_mono: ∀f,T,U1. ⬆*[f] T ≡ U1 → ∀U2. ⬆*[f] T ≡ U2 → U1 = U2.
+lemma lifts_mono: ∀f,T. is_mono … (lifts f T).
 #f #T #U1 #H1 #U2 #H2 lapply (after_isid_sn 𝐈𝐝  … f)
 /3 width=6 by lifts_conf, lifts_fwd_isid/
 qed-.
+
+lemma liftable2_sn_bi: ∀R. liftable2_sn R → liftable2_bi R.
+#R #HR #T1 #T2 #HT12 #f #U1 #HTU1 #U2 #HTU2
+elim (HR … HT12 … HTU1) -HR -T1 #X #HTX #HUX
+<(lifts_mono … HTX … HTU2) -T2 -U2 -f //
+qed-.
+
+lemma deliftable2_sn_bi: ∀R. deliftable2_sn R → deliftable2_bi R.
+#R #HR #U1 #U2 #HU12 #f #T1 #HTU1 #T2 #HTU2
+elim (HR … HU12 … HTU1) -HR -U1 #X #HUX #HTX
+<(lifts_inj … HUX … HTU2) -U2 -T2 -f //
+qed-.