Theorem 19.21h 1449

Description: Theorem 19.21 of [Margaris] p. 90. The hypothesis can be thought of as "𝑥 is not free in 𝜑." New proofs should use 19.21 1475 instead. (Contributed by NM, 5-Aug-1993.) (New usage is discouraged.)

Hypothesis

Ref	Expression
19.21h.1	⊢ (𝜑 → ∀𝑥𝜑)

Assertion

Ref	Expression
19.21h	⊢ (∀𝑥(𝜑 → 𝜓) ↔ (𝜑 → ∀𝑥𝜓))

Proof of Theorem 19.21h

Step	Hyp	Ref	Expression
1		19.21h.1	. . 3 ⊢ (𝜑 → ∀𝑥𝜑)
2		alim 1346	. . 3 ⊢ (∀𝑥(𝜑 → 𝜓) → (∀𝑥𝜑 → ∀𝑥𝜓))
3	1, 2	syl5 28	. 2 ⊢ (∀𝑥(𝜑 → 𝜓) → (𝜑 → ∀𝑥𝜓))
4		hba1 1433	. . . 4 ⊢ (∀𝑥𝜓 → ∀𝑥∀𝑥𝜓)
5	1, 4	hbim 1437	. . 3 ⊢ ((𝜑 → ∀𝑥𝜓) → ∀𝑥(𝜑 → ∀𝑥𝜓))
6		ax-4 1400	. . . 4 ⊢ (∀𝑥𝜓 → 𝜓)
7	6	imim2i 12	. . 3 ⊢ ((𝜑 → ∀𝑥𝜓) → (𝜑 → 𝜓))
8	5, 7	alrimih 1358	. 2 ⊢ ((𝜑 → ∀𝑥𝜓) → ∀𝑥(𝜑 → 𝜓))
9	3, 8	impbii 117	1 ⊢ (∀𝑥(𝜑 → 𝜓) ↔ (𝜑 → ∀𝑥𝜓))

Syntax hints:   → wi 4   ↔ wb 98  ∀wal 1241

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia2 100  ax-ia3 101  ax-5 1336  ax-gen 1338  ax-4 1400  ax-ial 1427  ax-i5r 1428

This theorem depends on definitions:  df-bi 110

This theorem is referenced by:  hbim1  1462  nf3  1559  19.21v  1753