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| Mirrors > Home > NFE Home > Th. List > ceqsexv | GIF version | ||
| Description: Elimination of an existential quantifier, using implicit substitution. (Contributed by NM, 2-Mar-1995.) |
| Ref | Expression |
|---|---|
| ceqsexv.1 | ⊢ A ∈ V |
| ceqsexv.2 | ⊢ (x = A → (φ ↔ ψ)) |
| Ref | Expression |
|---|---|
| ceqsexv | ⊢ (∃x(x = A ∧ φ) ↔ ψ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nfv 1619 | . 2 ⊢ Ⅎxψ | |
| 2 | ceqsexv.1 | . 2 ⊢ A ∈ V | |
| 3 | ceqsexv.2 | . 2 ⊢ (x = A → (φ ↔ ψ)) | |
| 4 | 1, 2, 3 | ceqsex 2894 | 1 ⊢ (∃x(x = A ∧ φ) ↔ ψ) |
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