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Description: Closed form of nfnth . (Contributed by BJ, 16-Sep-2021) (Proof shortened by Wolf Lammen, 4-Sep-2022)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | nfntht2 | ⊢ ( ∀ 𝑥 ¬ 𝜑 → Ⅎ 𝑥 𝜑 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | alnex | ⊢ ( ∀ 𝑥 ¬ 𝜑 ↔ ¬ ∃ 𝑥 𝜑 ) | |
| 2 | nfntht | ⊢ ( ¬ ∃ 𝑥 𝜑 → Ⅎ 𝑥 𝜑 ) | |
| 3 | 1 2 | sylbi | ⊢ ( ∀ 𝑥 ¬ 𝜑 → Ⅎ 𝑥 𝜑 ) |