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Description: Inference from existential specialization. (Contributed by NM, 19-Aug-1993) Use spimew . (Revised by Wolf Lammen, 22-Oct-2023)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | speiv.1 | ⊢ ( 𝑥 = 𝑦 → ( 𝜓 → 𝜑 ) ) | |
| speiv.2 | ⊢ 𝜓 | ||
| Assertion | speiv | ⊢ ∃ 𝑥 𝜑 |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | speiv.1 | ⊢ ( 𝑥 = 𝑦 → ( 𝜓 → 𝜑 ) ) | |
| 2 | speiv.2 | ⊢ 𝜓 | |
| 3 | 2 | hbth | ⊢ ( 𝜓 → ∀ 𝑥 𝜓 ) |
| 4 | 3 1 | spimew | ⊢ ( 𝜓 → ∃ 𝑥 𝜑 ) |
| 5 | 2 4 | ax-mp | ⊢ ∃ 𝑥 𝜑 |