Description: One direction of 19.37 from the same axioms as 19.37imv . (Contributed by BJ, 2-Dec-2023)
Ref | Expression | ||
---|---|---|---|
Assertion | bj-19.37im | ⊢ ( Ⅎ' 𝑥 𝜑 → ( ∃ 𝑥 ( 𝜑 → 𝜓 ) → ( 𝜑 → ∃ 𝑥 𝜓 ) ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 19.35 | ⊢ ( ∃ 𝑥 ( 𝜑 → 𝜓 ) ↔ ( ∀ 𝑥 𝜑 → ∃ 𝑥 𝜓 ) ) | |
2 | bj-nnfa | ⊢ ( Ⅎ' 𝑥 𝜑 → ( 𝜑 → ∀ 𝑥 𝜑 ) ) | |
3 | 2 | imim1d | ⊢ ( Ⅎ' 𝑥 𝜑 → ( ( ∀ 𝑥 𝜑 → ∃ 𝑥 𝜓 ) → ( 𝜑 → ∃ 𝑥 𝜓 ) ) ) |
4 | 1 3 | syl5bi | ⊢ ( Ⅎ' 𝑥 𝜑 → ( ∃ 𝑥 ( 𝜑 → 𝜓 ) → ( 𝜑 → ∃ 𝑥 𝜓 ) ) ) |