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 fc2e2ea85ca75abccc27963613769ea412dd60a5..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 ********************************************************************)
 
-(* Constructions with And ***************************************************)
+definition negation (A:Prop): Prop ≝
+           A → ⊥.
 
-lemma commutative_and: ∀A,B. A ∧ B → B ∧ A.
+(* Constructions with land **************************************************)
+
+lemma commutative_and (A) (B):
+      A ∧ B → B ∧ A.
 #A #B * /2 width=1 by conj/
 qed-.