Description: Define the unique homomorphism from the integers into a ring. This encodes the usual notation of n = 1r + 1r + ... + 1r for integers (see also df-mulg ). (Contributed by Mario Carneiro, 13-Jun-2015) (Revised by AV, 12-Jun-2019)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-zrh | |- ZRHom = ( r e. _V |-> U. ( ZZring RingHom r ) ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 0 | czrh | |- ZRHom | |
| 1 | vr | |- r | |
| 2 | cvv | |- _V | |
| 3 | czring | |- ZZring | |
| 4 | crh | |- RingHom | |
| 5 | 1 | cv | |- r | 
| 6 | 3 5 4 | co | |- ( ZZring RingHom r ) | 
| 7 | 6 | cuni | |- U. ( ZZring RingHom r ) | 
| 8 | 1 2 7 | cmpt | |- ( r e. _V |-> U. ( ZZring RingHom r ) ) | 
| 9 | 0 8 | wceq | |- ZRHom = ( r e. _V |-> U. ( ZZring RingHom r ) ) |