Description: A magma right and left identity belongs to the underlying set of the operation. (Contributed by FL, 12-Dec-2009) (Revised by Mario Carneiro, 22-Dec-2013) (New usage is discouraged.)
Ref | Expression | ||
---|---|---|---|
Hypotheses | iorlid.1 | |
|
iorlid.2 | |
||
Assertion | iorlid | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | iorlid.1 | |
|
2 | iorlid.2 | |
|
3 | 1 2 | idrval | |
4 | 1 | exidu1 | |
5 | riotacl | |
|
6 | 4 5 | syl | |
7 | 3 6 | eqeltrd | |