Description: An isomorphism of rings is an isomorphism of their additive groups. (Contributed by AV, 24-Dec-2019)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | rimgim | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | rimrhm | ||
| 2 | rhmghm | ||
| 3 | 1 2 | syl | |
| 4 | eqid | ||
| 5 | eqid | ||
| 6 | 4 5 | rimf1o | |
| 7 | 4 5 | isgim | |
| 8 | 3 6 7 | sylanbrc |