Theorem bj-wnf1 36693

Description: When 𝜑 is substituted for 𝜓, this is the first half of nonfreness (. → ∀) of the weak form of nonfreeness (∃ → ∀). (Contributed by BJ, 9-Dec-2023.)

Assertion

Ref	Expression
bj-wnf1	⊢ ((∃𝑥𝜑 → ∀𝑥𝜓) → ∀𝑥(∃𝑥𝜑 → ∀𝑥𝜓))

Proof of Theorem bj-wnf1

Step	Hyp	Ref	Expression
1		bj-modal4e 36691	. . 3 ⊢ (∃𝑥∃𝑥𝜑 → ∃𝑥𝜑)
2		hba1 2292	. . 3 ⊢ (∀𝑥𝜓 → ∀𝑥∀𝑥𝜓)
3	1, 2	imim12i 62	. 2 ⊢ ((∃𝑥𝜑 → ∀𝑥𝜓) → (∃𝑥∃𝑥𝜑 → ∀𝑥∀𝑥𝜓))
4		19.38 1838	. 2 ⊢ ((∃𝑥∃𝑥𝜑 → ∀𝑥∀𝑥𝜓) → ∀𝑥(∃𝑥𝜑 → ∀𝑥𝜓))
5	3, 4	syl 17	1 ⊢ ((∃𝑥𝜑 → ∀𝑥𝜓) → ∀𝑥(∃𝑥𝜑 → ∀𝑥𝜓))

Syntax hints:   → wi 4  ∀wal 1537  ∃wex 1778

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1794  ax-4 1808  ax-5 1909  ax-6 1966  ax-7 2006  ax-10 2140  ax-12 2176

This theorem depends on definitions:  df-bi 207  df-or 848  df-ex 1779  df-nf 1783

This theorem is referenced by:  bj-wnfanf  36695  bj-wnfenf  36696  bj-wnfnf  36715