- nnAuto: we catch TypeCheckerFailure generated at the end of

[helm.git] / matita / matita / contribs / lambdadelta / basic_2 / etc / fleq / fpbs.etc

diff --git a/matita/matita/contribs/lambdadelta/basic_2/etc/fleq/fpbs.etc b/matita/matita/contribs/lambdadelta/basic_2/etc/fleq/fpbs.etc
index 546994dfa83474bb2a9cf95ae1ba04faeef149ad..017421feb5afac7f6c4cdbc4a4ea59a92e629d79 100644 (file)
--- a/matita/matita/contribs/lambdadelta/basic_2/etc/fleq/fpbs.etc
+++ b/matita/matita/contribs/lambdadelta/basic_2/etc/fleq/fpbs.etc
@@ -1,3 +1,29 @@
+lemma fpbs_fpbu_sn: ∀h,g,G1,G2,L1,L2,T1,T2. ⦃G1, L1, T1⦄ ≥[h, g] ⦃G2, L2, T2⦄ →
+                    ⦃G1, L1, T1⦄ ≡[0] ⦃G2, L2, T2⦄ ∨
+                    ∃∃G,L,T. ⦃G1, L1, T1⦄ ≻[h, g] ⦃G, L, T⦄ & ⦃G, L, T⦄ ≥[h, g] ⦃G2, L2, T2⦄.
+(* ALTERNATIVE PROOF
+#h #g #G1 #G2 #L1 #L2 #T1 #T2 #H @(fpbs_ind_dx … H) -G1 -L1 -T1
+[ /2 width=1 by or_introl/
+| #G1 #G #L1 #L #T1 #T #H1 #_ * [ #H2 | * #G0 #L0 #T0 #H0 #H02 ]
+  elim (fpb_fpbu … H1) -H1 #H1
+  [ /3 width=1 by  
+*)
+#h #g #G1 #G2 #L1 #L2 #T1 #T2 #H elim(fpbs_inv_alt … H) -H
+#L0 #L #T #HT1 #HT2 #HL0 #HL2 elim (eq_term_dec T1 T) #H destruct
+[ -HT1 elim (fqus_inv_gen … HT2) -HT2
+  [ #H elim (fqup_inv_step_sn … H) -H
+    /4 width=11 by fpbs_intro_alt, fpbu_fqu, ex2_3_intro, or_intror/
+  | * #HG #HL #HT destruct elim (lleq_dec T2 L0 L 0) #H
+    [ /4 width=3 by fleq_intro, lleq_trans, or_introl/
+    | elim (lpxs_nlleq_inv_step_sn … HL0 H) -HL0 -H
+      /5 width=7 by lpxs_lleq_fpbs, fpbu_lpx, lleq_trans, ex2_3_intro, or_intror/
+    ]
+  ]
+| elim (cpxs_neq_inv_step_sn … HT1 H) -HT1 -H
+  /5 width=11 by fpbs_intro_alt, fpbu_cpx, ex2_3_intro, or_intror/
+]
+qed-.
+
 (* alternative proof that needs decidability of bteq to go in fpbs.ma 
  * or lpx_fpbc_trans to go in fpbs_lift.ma (possibly)  
 *)
@@ -20,3 +46,4 @@ lemma fpbs_fwd_fpb_sn: ∀h,g,G1,G2,L1,L2,T1,T2. ⦃G1, L1, T1⦄ ≥[h, g] ⦃G
   ]
 | #L0 #HL10 #_ * [ /3 width=3 by or_introl, lpx_bteq_trans/ ]
   * #G3 #L3 #T3 #H13 #H32
+