Description: Vacuous restricted uniqueness is always false. (Contributed by AV, 3-Apr-2023)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | reu0 | |- -. E! x e. (/) ph |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | rex0 | |- -. E. x e. (/) ph |
|
| 2 | reurex | |- ( E! x e. (/) ph -> E. x e. (/) ph ) |
|
| 3 | 1 2 | mto | |- -. E! x e. (/) ph |