Description: One direction of 19.37v that can be proven without ax-6 . (Contributed by Rohan Ridenour, 16-Apr-2022)
Ref | Expression | ||
---|---|---|---|
Assertion | 19.37imv | |- ( E. x ( ph -> ps ) -> ( ph -> E. x ps ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ax-5 | |- ( ph -> A. x ph ) |
|
2 | 19.35 | |- ( E. x ( ph -> ps ) <-> ( A. x ph -> E. x ps ) ) |
|
3 | 2 | biimpi | |- ( E. x ( ph -> ps ) -> ( A. x ph -> E. x ps ) ) |
4 | 1 3 | syl5 | |- ( E. x ( ph -> ps ) -> ( ph -> E. x ps ) ) |