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Theorem hbexg 39366
Description: Closed form of nfex 2324. Derived from hbexgVD 39726. (Contributed by Alan Sare, 8-Feb-2014.) (Revised by Mario Carneiro, 12-Dec-2016.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
hbexg (∀𝑥𝑦(𝜑 → ∀𝑥𝜑) → ∀𝑥𝑦(∃𝑦𝜑 → ∀𝑥𝑦𝜑))

Proof of Theorem hbexg
StepHypRef Expression
1 nfa2 2204 . . 3 𝑦𝑥𝑦(𝜑 → ∀𝑥𝜑)
2 sp 2215 . . . . . . 7 (∀𝑦(𝜑 → ∀𝑥𝜑) → (𝜑 → ∀𝑥𝜑))
32alimi 1906 . . . . . 6 (∀𝑥𝑦(𝜑 → ∀𝑥𝜑) → ∀𝑥(𝜑 → ∀𝑥𝜑))
4 nf5 2289 . . . . . 6 (Ⅎ𝑥𝜑 ↔ ∀𝑥(𝜑 → ∀𝑥𝜑))
53, 4sylibr 225 . . . . 5 (∀𝑥𝑦(𝜑 → ∀𝑥𝜑) → Ⅎ𝑥𝜑)
61, 5nfexd 2329 . . . 4 (∀𝑥𝑦(𝜑 → ∀𝑥𝜑) → Ⅎ𝑥𝑦𝜑)
7 nf5 2289 . . . 4 (Ⅎ𝑥𝑦𝜑 ↔ ∀𝑥(∃𝑦𝜑 → ∀𝑥𝑦𝜑))
86, 7sylib 209 . . 3 (∀𝑥𝑦(𝜑 → ∀𝑥𝜑) → ∀𝑥(∃𝑦𝜑 → ∀𝑥𝑦𝜑))
91, 8alrimi 2246 . 2 (∀𝑥𝑦(𝜑 → ∀𝑥𝜑) → ∀𝑦𝑥(∃𝑦𝜑 → ∀𝑥𝑦𝜑))
10 alcom 2201 . 2 (∀𝑦𝑥(∃𝑦𝜑 → ∀𝑥𝑦𝜑) ↔ ∀𝑥𝑦(∃𝑦𝜑 → ∀𝑥𝑦𝜑))
119, 10sylib 209 1 (∀𝑥𝑦(𝜑 → ∀𝑥𝜑) → ∀𝑥𝑦(∃𝑦𝜑 → ∀𝑥𝑦𝜑))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wal 1650  wex 1874  wnf 1878
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1890  ax-4 1904  ax-5 2005  ax-6 2069  ax-7 2105  ax-10 2183  ax-11 2198  ax-12 2211
This theorem depends on definitions:  df-bi 198  df-or 874  df-ex 1875  df-nf 1879
This theorem is referenced by: (None)
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