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 ) ) |