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Theorem nfalt 1486
 Description: Closed form of nfal 1484. (Contributed by Jim Kingdon, 11-May-2018.)
Assertion
Ref Expression
nfalt (∀𝑦𝑥𝜑 → Ⅎ𝑥𝑦𝜑)

Proof of Theorem nfalt
StepHypRef Expression
1 alim 1362 . . . 4 (∀𝑦(𝜑 → ∀𝑥𝜑) → (∀𝑦𝜑 → ∀𝑦𝑥𝜑))
2 alcom 1383 . . . 4 (∀𝑦𝑥𝜑 ↔ ∀𝑥𝑦𝜑)
31, 2syl6ib 154 . . 3 (∀𝑦(𝜑 → ∀𝑥𝜑) → (∀𝑦𝜑 → ∀𝑥𝑦𝜑))
43alimi 1360 . 2 (∀𝑥𝑦(𝜑 → ∀𝑥𝜑) → ∀𝑥(∀𝑦𝜑 → ∀𝑥𝑦𝜑))
5 df-nf 1366 . . . 4 (Ⅎ𝑥𝜑 ↔ ∀𝑥(𝜑 → ∀𝑥𝜑))
65albii 1375 . . 3 (∀𝑦𝑥𝜑 ↔ ∀𝑦𝑥(𝜑 → ∀𝑥𝜑))
7 alcom 1383 . . 3 (∀𝑦𝑥(𝜑 → ∀𝑥𝜑) ↔ ∀𝑥𝑦(𝜑 → ∀𝑥𝜑))
86, 7bitri 177 . 2 (∀𝑦𝑥𝜑 ↔ ∀𝑥𝑦(𝜑 → ∀𝑥𝜑))
9 df-nf 1366 . 2 (Ⅎ𝑥𝑦𝜑 ↔ ∀𝑥(∀𝑦𝜑 → ∀𝑥𝑦𝜑))
104, 8, 93imtr4i 194 1 (∀𝑦𝑥𝜑 → Ⅎ𝑥𝑦𝜑)
 Colors of variables: wff set class Syntax hints:   → wi 4  ∀wal 1257  Ⅎwnf 1365 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-ia3 105  ax-5 1352  ax-7 1353  ax-gen 1354 This theorem depends on definitions:  df-bi 114  df-nf 1366 This theorem is referenced by:  dvelimor  1910
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