colength and identity relocation

[helm.git] / matita / matita / contribs / lambdadelta / ground_2 / lib / bool.ma

diff --git a/matita/matita/contribs/lambdadelta/ground_2/lib/bool.ma b/matita/matita/contribs/lambdadelta/ground_2/lib/bool.ma
index d2acdb2bc79c4ad3e2862072d9567056407650d7..680cc4ac2afde0c61169bd9da1c0c78b7923bec5 100644 (file)
--- a/matita/matita/contribs/lambdadelta/ground_2/lib/bool.ma
+++ b/matita/matita/contribs/lambdadelta/ground_2/lib/bool.ma
@@ -32,6 +32,12 @@ qed-.
 lemma commutative_orb: commutative … orb.
 * * // qed.
 
+lemma orb_true_dx: ∀b. (b ∨ Ⓣ) = Ⓣ.
+* // qed.
+
+lemma orb_true_sn: ∀b. (Ⓣ ∨ b) = Ⓣ.
+// qed.
+
 lemma eq_bool_dec: ∀b1,b2:bool. Decidable (b1 = b2).
 * * /2 width=1 by or_introl/
 @or_intror #H destruct