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Description: Existential specialization, using implicit substitution. (Contributed by NM, 14-Aug-1994) Avoid ax-10 , ax-11 . (Revised by Wolf Lammen, 25-Aug-2023)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | spcgv.1 | |- ( x = A -> ( ph <-> ps ) ) |
|
| Assertion | spcegv | |- ( A e. V -> ( ps -> E. x ph ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | spcgv.1 | |- ( x = A -> ( ph <-> ps ) ) |
|
| 2 | elisset | |- ( A e. V -> E. x x = A ) |
|
| 3 | 1 | biimprcd | |- ( ps -> ( x = A -> ph ) ) |
| 4 | 3 | eximdv | |- ( ps -> ( E. x x = A -> E. x ph ) ) |
| 5 | 2 4 | syl5com | |- ( A e. V -> ( ps -> E. x ph ) ) |