Theorem ra4 3799

Description: Restricted quantifier version of Axiom 5 of [Mendelson] p. 69. This is the axiom stdpc5 2172 of standard predicate calculus for a restricted domain. See ra4v 3798 for a version requiring fewer axioms. (Contributed by NM, 16-Jan-2004.) (Proof shortened by BJ, 27-Mar-2020.)

Hypothesis

Ref	Expression
ra4.1	⊢ Ⅎ𝑥𝜑

Assertion

Ref	Expression
ra4	⊢ (∀𝑥 ∈ 𝐴 (𝜑 → 𝜓) → (𝜑 → ∀𝑥 ∈ 𝐴 𝜓))

Proof of Theorem ra4

Step	Hyp	Ref	Expression
1		ra4.1	. . 3 ⊢ Ⅎ𝑥𝜑
2	1	r19.21 3181	. 2 ⊢ (∀𝑥 ∈ 𝐴 (𝜑 → 𝜓) ↔ (𝜑 → ∀𝑥 ∈ 𝐴 𝜓))
3	2	biimpi 217	1 ⊢ (∀𝑥 ∈ 𝐴 (𝜑 → 𝜓) → (𝜑 → ∀𝑥 ∈ 𝐴 𝜓))

Syntax hints:   → wi 4  Ⅎwnf 1766  ∀wral 3104

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1778  ax-4 1792  ax-5 1889  ax-6 1948  ax-7 1993  ax-12 2140

This theorem depends on definitions:  df-bi 208  df-ex 1763  df-nf 1767  df-ral 3109

This theorem is referenced by: (None)