update in ground_2 + \lambda\delta-related ignores

[helm.git] / matita / matita / contribs / lambdadelta / ground_2 / xoa / xoa_props.ma

diff --git a/matita/matita/contribs/lambdadelta/ground_2/xoa/xoa_props.ma b/matita/matita/contribs/lambdadelta/ground_2/xoa/xoa_props.ma
index 408e1933dec9e3c55744a695c6c63f6a22e8238e..530c0e2b39541f81f971847c667b4f317a41a108 100644 (file)
--- a/matita/matita/contribs/lambdadelta/ground_2/xoa/xoa_props.ma
+++ b/matita/matita/contribs/lambdadelta/ground_2/xoa/xoa_props.ma
@@ -22,3 +22,9 @@ include "ground_2/xoa/xoa.ma".
 interpretation "logical false" 'false = False.
 
 interpretation "logical true" 'true = True.
+
+(* Logical properties missing in the basic library **************************) 
+
+lemma commutative_and: ∀A,B. A ∧ B → B ∧ A.
+#A #B * /2 width=1 by conj/
+qed-.