Description: Prove an existential. (Contributed by Rohan Ridenour, 12-Aug-2023)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | rr-spce.1 | |- ( ( ph /\ x = A ) -> ps ) |
|
| rr-spce.2 | |- ( ph -> A e. V ) |
||
| Assertion | rr-spce | |- ( ph -> E. x ps ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | rr-spce.1 | |- ( ( ph /\ x = A ) -> ps ) |
|
| 2 | rr-spce.2 | |- ( ph -> A e. V ) |
|
| 3 | 2 | elexd | |- ( ph -> A e. _V ) |
| 4 | isset | |- ( A e. _V <-> E. x x = A ) |
|
| 5 | 3 4 | sylib | |- ( ph -> E. x x = A ) |
| 6 | 1 | ex | |- ( ph -> ( x = A -> ps ) ) |
| 7 | 6 | eximdv | |- ( ph -> ( E. x x = A -> E. x ps ) ) |
| 8 | 5 7 | mpd | |- ( ph -> E. x ps ) |