- revision of ground_2 and basic_2

[helm.git] / matita / matita / contribs / lambdadelta / basic_2 / multiple / drops_drop.ma

diff --git a/matita/matita/contribs/lambdadelta/basic_2/multiple/drops_drop.ma b/matita/matita/contribs/lambdadelta/basic_2/multiple/drops_drop.ma
index 2f9a34c08b08c26388f020c78fbc63b66906cb91..2bf29c6366a3b11711390c4fd72274f7ca738654 100644 (file)
--- a/matita/matita/contribs/lambdadelta/basic_2/multiple/drops_drop.ma
+++ b/matita/matita/contribs/lambdadelta/basic_2/multiple/drops_drop.ma
@@ -25,8 +25,8 @@ lemma drops_drop_trans: ∀L1,L,cs. ⬇*[Ⓕ, cs] L1 ≡ L → ∀L2,i. ⬇[i] L
 #L1 #L #cs #H elim H -L1 -L -cs
 [ /2 width=7 by drops_nil, minuss_nil, at_nil, ex4_3_intro/
 | #L1 #L0 #L #cs #l #m #_ #HL0 #IHL0 #L2 #i #HL2
-  elim (lt_or_ge i l) #Hil
-  [ elim (drop_trans_le … HL0 … HL2) -L /2 width=2 by lt_to_le/
+  elim (ylt_split i l) #Hil
+  [ elim (drop_trans_le … HL0 … HL2) -L /2 width=2 by ylt_fwd_le/
     #L #HL0 #HL2 elim (IHL0 … HL0) -L0 /3 width=7 by drops_cons, minuss_lt, at_lt, ex4_3_intro/
   | lapply (drop_trans_ge … HL0 … HL2 ?) -L // #HL02
     elim (IHL0 … HL02) -L0 /3 width=7 by minuss_ge, at_ge, ex4_3_intro/