include "ground/notation/xoa/or_2.ma".
include "ground/notation/xoa/and_2.ma".
-interpretation "logical false" 'false = False.
+interpretation
+ "false (logic)"
+ 'false = False.
-interpretation "logical true" 'true = True.
+interpretation
+ "true (logic)"
+ 'true = True.
-(* Logical properties missing in the basic library **************************)
+(* LOGIC ********************************************************************)
-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-.