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Theorem ax4 32699
 Description: Rederivation of axiom ax-4 1711 from ax-c4 32689 and other older axioms. See axc4 1991 for the derivation of ax-c4 32689 from ax-4 1711. (Contributed by NM, 23-May-2008.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
ax4 (∀𝑥(𝜑𝜓) → (∀𝑥𝜑 → ∀𝑥𝜓))

Proof of Theorem ax4
StepHypRef Expression
1 ax-c4 32689 . . 3 (∀𝑥(∀𝑥(𝜑𝜓) → (∀𝑥𝜑𝜓)) → (∀𝑥(𝜑𝜓) → ∀𝑥(∀𝑥𝜑𝜓)))
2 ax-c5 32688 . . . 4 (∀𝑥𝜑𝜑)
3 ax-c5 32688 . . . 4 (∀𝑥(𝜑𝜓) → (𝜑𝜓))
42, 3syl5 33 . . 3 (∀𝑥(𝜑𝜓) → (∀𝑥𝜑𝜓))
51, 4mpg 1700 . 2 (∀𝑥(𝜑𝜓) → ∀𝑥(∀𝑥𝜑𝜓))
6 ax-c4 32689 . 2 (∀𝑥(∀𝑥𝜑𝜓) → (∀𝑥𝜑 → ∀𝑥𝜓))
75, 6syl 17 1 (∀𝑥(𝜑𝜓) → (∀𝑥𝜑 → ∀𝑥𝜓))
 Colors of variables: wff setvar class Syntax hints:   → wi 4  ∀wal 1466 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-gen 1698  ax-c5 32688  ax-c4 32689 This theorem is referenced by: (None)
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