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Description: Closed form of nfth . (Contributed by Wolf Lammen, 19-Aug-2018) (Proof shortened by BJ, 16-Sep-2021) (Proof shortened by Wolf Lammen, 3-Sep-2022)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | nftht | ⊢ ( ∀ 𝑥 𝜑 → Ⅎ 𝑥 𝜑 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ax-1 | ⊢ ( ∀ 𝑥 𝜑 → ( ∃ 𝑥 𝜑 → ∀ 𝑥 𝜑 ) ) | |
| 2 | 1 | nfd | ⊢ ( ∀ 𝑥 𝜑 → Ⅎ 𝑥 𝜑 ) |