- ng_kernel: we print the offending term when guarded_by_constructors fails

[helm.git] / matita / matita / contribs / lambdadelta / basic_2 / relocation / lexs.ma

diff --git a/matita/matita/contribs/lambdadelta/basic_2/relocation/lexs.ma b/matita/matita/contribs/lambdadelta/basic_2/relocation/lexs.ma
index 8140a5d31091fcb23900b7c69d3a5c8929f9d591..a79a3e4d9a3559d2077584c65778844da9aa1d77 100644 (file)
--- a/matita/matita/contribs/lambdadelta/basic_2/relocation/lexs.ma
+++ b/matita/matita/contribs/lambdadelta/basic_2/relocation/lexs.ma
@@ -145,6 +145,13 @@ lemma lexs_inv_push: ∀RN,RP,I1,I2,L1,L2,V1,V2,f.
 #L0 #V0 #HL10 #HV10 #H destruct /2 width=1 by and3_intro/
 qed-.
 
+lemma lexs_inv_tl: ∀RN,RP,I,L1,L2,V1,V2,f. L1 ⦻*[RN, RP, ⫱f] L2 →
+                   RN L1 V1 V2 → RP L1 V1 V2 → 
+                   L1.ⓑ{I}V1 ⦻*[RN, RP, f] L2.ⓑ{I}V2.
+#RN #RP #I #L2 #L2 #V1 #V2 #f elim (pn_split f) *
+/2 width=1 by lexs_next, lexs_push/
+qed-.
+
 (* Basic properties *********************************************************)
 
 lemma lexs_eq_repl_back: ∀RN,RP,L1,L2. eq_repl_back … (λf. L1 ⦻*[RN, RP, f] L2).