Description: Any proposition holds for some x or holds for at most one x . (Contributed by NM, 8-Mar-1995) Shorten proof and avoid df-eu . (Revised by BJ, 14-Oct-2022)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | exmo | |- ( E. x ph \/ E* x ph ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nexmo | |- ( -. E. x ph -> E* x ph ) |
|
| 2 | 1 | orri | |- ( E. x ph \/ E* x ph ) |