more results on strongly normalizing terms

[helm.git] / matita / matita / contribs / lambda_delta / Basic_2 / reducibility / cnf.ma

diff --git a/matita/matita/contribs/lambda_delta/Basic_2/reducibility/cnf.ma b/matita/matita/contribs/lambda_delta/Basic_2/reducibility/cnf.ma
index 50ff046038f7e1cfbc6894d15d2fcaf1f56ae047..39ac692cda6d0b0a09239d36598d4d443def5a34 100644 (file)
--- a/matita/matita/contribs/lambda_delta/Basic_2/reducibility/cnf.ma
+++ b/matita/matita/contribs/lambda_delta/Basic_2/reducibility/cnf.ma
@@ -30,4 +30,7 @@ lemma cnf_sort: ∀L,k. L ⊢ 𝐍[⋆k].
 >(cpr_inv_sort1 … H) //
 qed.
 
+axiom cnf_dec: ∀L,T1. L ⊢ 𝐍[T1] ∨
+               ∃∃T2. L ⊢ T1 ➡ T2 & (T1 = T2 → False).
+
 (* Basic_1: removed theorems 1: nf2_abst_shift *)