2015-02-23 02:20:27 +00:00
|
|
|
import algebra.group
|
|
|
|
open algebra
|
|
|
|
|
2015-04-22 02:33:21 +00:00
|
|
|
section
|
2015-02-23 02:20:27 +00:00
|
|
|
variable {A : Type}
|
|
|
|
variable [s : comm_monoid A]
|
|
|
|
include s
|
|
|
|
|
2015-05-18 22:45:23 +00:00
|
|
|
theorem one_mul_one : 1 * 1 = (1:A) :=
|
2015-02-23 02:20:27 +00:00
|
|
|
mul_one 1
|
|
|
|
end
|
|
|
|
|
|
|
|
definition one [reducible] (A : Type) [s : has_one A] : A :=
|
|
|
|
!has_one.one
|
|
|
|
|
2015-04-22 02:33:21 +00:00
|
|
|
section
|
2015-02-23 02:20:27 +00:00
|
|
|
variable {A : Type}
|
|
|
|
variable [s : comm_group A]
|
|
|
|
include s
|
|
|
|
|
|
|
|
theorem one_mul_one2 : (one A) * 1 = 1 :=
|
|
|
|
by rewrite one_mul_one
|
|
|
|
end
|