Theorem bj-wnfenf 34073

Description: When 𝜑 is substituted for 𝜓, this statement expresses that weak nonfreeness implies the "exists" form of nonfreeness. (Contributed by BJ, 9-Dec-2023.)

Assertion

Ref	Expression
bj-wnfenf	⊢ ((∃𝑥𝜑 → ∀𝑥𝜓) → ∀𝑥(∃𝑥𝜑 → 𝜓))

Proof of Theorem bj-wnfenf

Step	Hyp	Ref	Expression
1		bj-wnf1 34070	. 2 ⊢ ((∃𝑥𝜑 → ∀𝑥𝜓) → ∀𝑥(∃𝑥𝜑 → ∀𝑥𝜓))
2		bj-19.21bit 34043	. 2 ⊢ ((∃𝑥𝜑 → ∀𝑥𝜓) → (∃𝑥𝜑 → 𝜓))
3	1, 2	sylg 1822	1 ⊢ ((∃𝑥𝜑 → ∀𝑥𝜓) → ∀𝑥(∃𝑥𝜑 → 𝜓))

Syntax hints:   → wi 4  ∀wal 1534  ∃wex 1779

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795  ax-4 1809  ax-5 1910  ax-6 1969  ax-7 2014  ax-10 2144  ax-12 2176

This theorem depends on definitions:  df-bi 209  df-or 844  df-ex 1780  df-nf 1784

This theorem is referenced by: (None)