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Description: Elimination of an existential quantifier, using implicit substitution. (Contributed by Thierry Arnoux, 10-Sep-2016) Shorten, reduce dv conditions. (Revised by Wolf Lammen, 5-Jun-2025) (Proof shortened by SN, 5-Jun-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | ceqsexv2d.1 | |- A e. _V |
|
| ceqsexv2d.2 | |- ( x = A -> ( ph <-> ps ) ) |
||
| ceqsexv2d.3 | |- ps |
||
| Assertion | ceqsexv2d | |- E. x ph |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ceqsexv2d.1 | |- A e. _V |
|
| 2 | ceqsexv2d.2 | |- ( x = A -> ( ph <-> ps ) ) |
|
| 3 | ceqsexv2d.3 | |- ps |
|
| 4 | 1 | isseti | |- E. x x = A |
| 5 | 3 2 | mpbiri | |- ( x = A -> ph ) |
| 6 | 4 5 | eximii | |- E. x ph |