Theorem bj-nfimt 32025

Description: Closed form of nfim 1813. (Contributed by BJ, 20-Oct-2021.) (Proof modification is discouraged.)

Assertion

Ref	Expression
bj-nfimt	⊢ (Ⅎ𝑥𝜑 → (Ⅎ𝑥𝜓 → Ⅎ𝑥(𝜑 → 𝜓)))

Proof of Theorem bj-nfimt

Step	Hyp	Ref	Expression
1		19.35 1794	. . 3 ⊢ (∃𝑥(𝜑 → 𝜓) ↔ (∀𝑥𝜑 → ∃𝑥𝜓))
2		df-nf 1701	. . . . . . 7 ⊢ (Ⅎ𝑥𝜑 ↔ (∃𝑥𝜑 → ∀𝑥𝜑))
3	2	biimpi 205	. . . . . 6 ⊢ (Ⅎ𝑥𝜑 → (∃𝑥𝜑 → ∀𝑥𝜑))
4	3	imim1d 80	. . . . 5 ⊢ (Ⅎ𝑥𝜑 → ((∀𝑥𝜑 → ∃𝑥𝜓) → (∃𝑥𝜑 → ∃𝑥𝜓)))
5		df-nf 1701	. . . . . . 7 ⊢ (Ⅎ𝑥𝜓 ↔ (∃𝑥𝜓 → ∀𝑥𝜓))
6	5	biimpi 205	. . . . . 6 ⊢ (Ⅎ𝑥𝜓 → (∃𝑥𝜓 → ∀𝑥𝜓))
7	6	imim2d 55	. . . . 5 ⊢ (Ⅎ𝑥𝜓 → ((∃𝑥𝜑 → ∃𝑥𝜓) → (∃𝑥𝜑 → ∀𝑥𝜓)))
8	4, 7	syl9 75	. . . 4 ⊢ (Ⅎ𝑥𝜑 → (Ⅎ𝑥𝜓 → ((∀𝑥𝜑 → ∃𝑥𝜓) → (∃𝑥𝜑 → ∀𝑥𝜓))))
9		19.38 1757	. . . 4 ⊢ ((∃𝑥𝜑 → ∀𝑥𝜓) → ∀𝑥(𝜑 → 𝜓))
10	8, 9	syl8 74	. . 3 ⊢ (Ⅎ𝑥𝜑 → (Ⅎ𝑥𝜓 → ((∀𝑥𝜑 → ∃𝑥𝜓) → ∀𝑥(𝜑 → 𝜓))))
11	1, 10	syl7bi 244	. 2 ⊢ (Ⅎ𝑥𝜑 → (Ⅎ𝑥𝜓 → (∃𝑥(𝜑 → 𝜓) → ∀𝑥(𝜑 → 𝜓))))
12		df-nf 1701	. 2 ⊢ (Ⅎ𝑥(𝜑 → 𝜓) ↔ (∃𝑥(𝜑 → 𝜓) → ∀𝑥(𝜑 → 𝜓)))
13	11, 12	syl6ibr 241	1 ⊢ (Ⅎ𝑥𝜑 → (Ⅎ𝑥𝜓 → Ⅎ𝑥(𝜑 → 𝜓)))

Syntax hints:   → wi 4  ∀wal 1473  ∃wex 1695  Ⅎwnf 1699

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728

This theorem depends on definitions:  df-bi 196  df-ex 1696  df-nf 1701

This theorem is referenced by:  bj-nfimt2  32026  bj-dvelimdv1  32028