Description: Second property of three of the provability predicate. (Contributed by BJ, 3-Apr-2019)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | ax-prv2 | |- ( Prv ( ph -> ps ) -> ( Prv ph -> Prv ps ) ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 0 | wph | |- ph | |
| 1 | wps | |- ps | |
| 2 | 0 1 | wi | |- ( ph -> ps ) | 
| 3 | 2 | cprvb | |- Prv ( ph -> ps ) | 
| 4 | 0 | cprvb | |- Prv ph | 
| 5 | 1 | cprvb | |- Prv ps | 
| 6 | 4 5 | wi | |- ( Prv ph -> Prv ps ) | 
| 7 | 3 6 | wi | |- ( Prv ( ph -> ps ) -> ( Prv ph -> Prv ps ) ) |