Description: The unity element of a ring is a left multiplicative identity. (Contributed by NM, 15-Sep-2011)
Ref | Expression | ||
---|---|---|---|
Hypotheses | ringidm.b | |
|
ringidm.t | |
||
ringidm.u | |
||
Assertion | ringlidm | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ringidm.b | |
|
2 | ringidm.t | |
|
3 | ringidm.u | |
|
4 | 1 2 3 | ringidmlem | |
5 | 4 | simpld | |