(* *)
(**************************************************************************)
-set "baseuri" "cic:/matita/algebra/monoids/".
-
include "algebra/semigroups.ma".
record PreMonoid : Type ≝
e: magma
}.
+(* FG: the interpretation goes just after its definition *)
+interpretation "Monoid unit" 'neutral = (e ?).
+
record isMonoid (M:PreMonoid) : Prop ≝
{ is_semi_group:> isSemiGroup M;
e_is_left_unit:
{ premonoid:> PreMonoid;
monoid_properties:> isMonoid premonoid
}.
-
-notation "1" with precedence 89
-for @{ 'munit }.
-
-interpretation "Monoid unit" 'munit =
- (cic:/matita/algebra/monoids/e.con _).
definition is_left_inverse ≝
λM:Monoid.
λopp: M → M.
- ∀x:M. (opp x)·x = 1.
+ ∀x:M. (opp x)·x = ⅇ.
definition is_right_inverse ≝
λM:Monoid.
λopp: M → M.
- ∀x:M. x·(opp x) = 1.
+ ∀x:M. x·(opp x) = ⅇ.
theorem is_left_inverse_to_is_right_inverse_to_eq:
∀M:Monoid. ∀l,r.