update in ground

[helm.git] / matita / matita / contribs / lambdadelta / ground / lib / logic.ma

diff --git a/matita/matita/contribs/lambdadelta/ground/lib/logic.ma b/matita/matita/contribs/lambdadelta/ground/lib/logic.ma
index 1de5ee4c01018fcfd4396dc7d1ad9d2e3f0f0eca..8786e77aeb7556e003d1041be68190c27e7d1d10 100644 (file)
--- a/matita/matita/contribs/lambdadelta/ground/lib/logic.ma
+++ b/matita/matita/contribs/lambdadelta/ground/lib/logic.ma
@@ -28,8 +28,12 @@ interpretation
 
 (* LOGIC ********************************************************************)
 
+definition negation (A:Prop): Prop ≝
+           A → ⊥.
+
 (* Constructions with land **************************************************)
 
-lemma commutative_and: ∀A,B. A ∧ B → B ∧ A.
+lemma commutative_and (A) (B):
+      A ∧ B → B ∧ A.
 #A #B * /2 width=1 by conj/
 qed-.