Description: Define the successor function. See brsuccf for its value. (Contributed by Scott Fenton, 14-Apr-2014)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-succf | |- Succ = ( Cup o. ( _I (x) Singleton ) ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 0 | csuccf | |- Succ | |
| 1 | ccup | |- Cup | |
| 2 | cid | |- _I | |
| 3 | csingle | |- Singleton | |
| 4 | 2 3 | ctxp | |- ( _I (x) Singleton ) | 
| 5 | 1 4 | ccom | |- ( Cup o. ( _I (x) Singleton ) ) | 
| 6 | 0 5 | wceq | |- Succ = ( Cup o. ( _I (x) Singleton ) ) |