Description: Bound-variable hypothesis builder for the unique existential quantifier. Version of nfeu with a disjoint variable condition, which does not require ax-13 . (Contributed by NM, 8-Mar-1995) (Revised by Gino Giotto, 10-Jan-2024)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | nfeuw.1 | |- F/ x ph |
|
| Assertion | nfeuw | |- F/ x E! y ph |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nfeuw.1 | |- F/ x ph |
|
| 2 | nftru | |- F/ y T. |
|
| 3 | 1 | a1i | |- ( T. -> F/ x ph ) |
| 4 | 2 3 | nfeudw | |- ( T. -> F/ x E! y ph ) |
| 5 | 4 | mptru | |- F/ x E! y ph |