Metamath Proof Explorer
Description: The base set of a monoid is not empty. Statement in Lang p. 3.
(Contributed by AV, 29-Dec-2023)
|
|
Ref |
Expression |
|
Hypothesis |
mndbn0.b |
|
|
Assertion |
mndbn0 |
|
Proof
| Step |
Hyp |
Ref |
Expression |
| 1 |
|
mndbn0.b |
|
| 2 |
|
eqid |
|
| 3 |
1 2
|
mndidcl |
|
| 4 |
3
|
ne0d |
|