X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fbasic_2%2Frt_computation%2Fcsx_cnx.ma;h=ea34597b9fef2e09073ef5c762b9e11e5cd41649;hb=c3832abc23bb0907df2deb6751f4a46d213675b7;hp=8f9268fabdebc14beb748b0408f85540bfecff4d;hpb=228776cd21ca563e6dc44bfdf7746e69dc7b66d6;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/basic_2/rt_computation/csx_cnx.ma b/matita/matita/contribs/lambdadelta/basic_2/rt_computation/csx_cnx.ma
index 8f9268fab..ea34597b9 100644
--- a/matita/matita/contribs/lambdadelta/basic_2/rt_computation/csx_cnx.ma
+++ b/matita/matita/contribs/lambdadelta/basic_2/rt_computation/csx_cnx.ma
@@ -22,3 +22,16 @@ include "basic_2/rt_computation/csx.ma".
 (* Basic_1: was just: sn3_nf2 *)
 lemma cnx_csx: ∀h,o,G,L,T. ⦃G, L⦄ ⊢ ⬈[h, o] 𝐍⦃T⦄ → ⦃G, L⦄ ⊢ ⬈*[h, o] 𝐒⦃T⦄.
 /2 width=1 by NF_to_SN/ qed.
+
+(* Advanced properties ******************************************************)
+
+lemma csx_sort: ∀h,o,G,L,s. ⦃G, L⦄ ⊢ ⬈*[h, o] 𝐒⦃⋆s⦄.
+#h #o #G #L #s elim (deg_total h o s)
+#d generalize in match s; -s elim d -d
+[ /3 width=3 by cnx_csx, cnx_sort/
+| #d #IH #s #Hsd lapply (deg_next_SO … Hsd) -Hsd
+  #Hsd @csx_intro #X #H #HX
+  elim (cpx_inv_sort1 … H) -H #H destruct /2 width=1 by/
+  elim HX -HX //
+]
+qed.