Description: If a proposition holds, then it holds for all values of a given variable if and only if it does not depend on that variable. (Contributed by BJ, 28-Mar-2026)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | bj-alnnf2 | ⊢ ( 𝜑 → ( ∀ 𝑥 𝜑 ↔ Ⅎ' 𝑥 𝜑 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | bj-alnnf | ⊢ ( ( 𝜑 → ∀ 𝑥 𝜑 ) ↔ ( 𝜑 → Ⅎ' 𝑥 𝜑 ) ) | |
| 2 | 1 | pm5.74ri | ⊢ ( 𝜑 → ( ∀ 𝑥 𝜑 ↔ Ⅎ' 𝑥 𝜑 ) ) |