Description: Version of 19.32 with a disjoint variable condition, requiring fewer axioms. (Contributed by BJ, 7-Mar-2020)
Ref | Expression | ||
---|---|---|---|
Assertion | 19.32v | ⊢ ( ∀ 𝑥 ( 𝜑 ∨ 𝜓 ) ↔ ( 𝜑 ∨ ∀ 𝑥 𝜓 ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 19.21v | ⊢ ( ∀ 𝑥 ( ¬ 𝜑 → 𝜓 ) ↔ ( ¬ 𝜑 → ∀ 𝑥 𝜓 ) ) | |
2 | df-or | ⊢ ( ( 𝜑 ∨ 𝜓 ) ↔ ( ¬ 𝜑 → 𝜓 ) ) | |
3 | 2 | albii | ⊢ ( ∀ 𝑥 ( 𝜑 ∨ 𝜓 ) ↔ ∀ 𝑥 ( ¬ 𝜑 → 𝜓 ) ) |
4 | df-or | ⊢ ( ( 𝜑 ∨ ∀ 𝑥 𝜓 ) ↔ ( ¬ 𝜑 → ∀ 𝑥 𝜓 ) ) | |
5 | 1 3 4 | 3bitr4i | ⊢ ( ∀ 𝑥 ( 𝜑 ∨ 𝜓 ) ↔ ( 𝜑 ∨ ∀ 𝑥 𝜓 ) ) |