Description: Closed form of nexdv . (Contributed by BJ, 20-Oct-2019)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | bj-nexdvt | |- ( A. x ( ph -> -. ps ) -> ( ph -> -. E. x ps ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nfv | |- F/ x ph |
|
| 2 | bj-nexdt | |- ( F/ x ph -> ( A. x ( ph -> -. ps ) -> ( ph -> -. E. x ps ) ) ) |
|
| 3 | 1 2 | ax-mp | |- ( A. x ( ph -> -. ps ) -> ( ph -> -. E. x ps ) ) |