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Theorem axextdist 31829
 Description: ax-ext 2631 with distinctors instead of distinct variable restrictions. (Contributed by Scott Fenton, 13-Dec-2010.)
Assertion
Ref Expression
axextdist ((¬ ∀𝑧 𝑧 = 𝑥 ∧ ¬ ∀𝑧 𝑧 = 𝑦) → (∀𝑧(𝑧𝑥𝑧𝑦) → 𝑥 = 𝑦))

Proof of Theorem axextdist
Dummy variable 𝑤 is distinct from all other variables.
StepHypRef Expression
1 nfnae 2351 . . . 4 𝑧 ¬ ∀𝑧 𝑧 = 𝑥
2 nfnae 2351 . . . 4 𝑧 ¬ ∀𝑧 𝑧 = 𝑦
31, 2nfan 1868 . . 3 𝑧(¬ ∀𝑧 𝑧 = 𝑥 ∧ ¬ ∀𝑧 𝑧 = 𝑦)
4 nfcvf 2817 . . . . . 6 (¬ ∀𝑧 𝑧 = 𝑥𝑧𝑥)
54adantr 480 . . . . 5 ((¬ ∀𝑧 𝑧 = 𝑥 ∧ ¬ ∀𝑧 𝑧 = 𝑦) → 𝑧𝑥)
65nfcrd 2800 . . . 4 ((¬ ∀𝑧 𝑧 = 𝑥 ∧ ¬ ∀𝑧 𝑧 = 𝑦) → Ⅎ𝑧 𝑤𝑥)
7 nfcvf 2817 . . . . . 6 (¬ ∀𝑧 𝑧 = 𝑦𝑧𝑦)
87adantl 481 . . . . 5 ((¬ ∀𝑧 𝑧 = 𝑥 ∧ ¬ ∀𝑧 𝑧 = 𝑦) → 𝑧𝑦)
98nfcrd 2800 . . . 4 ((¬ ∀𝑧 𝑧 = 𝑥 ∧ ¬ ∀𝑧 𝑧 = 𝑦) → Ⅎ𝑧 𝑤𝑦)
106, 9nfbid 1872 . . 3 ((¬ ∀𝑧 𝑧 = 𝑥 ∧ ¬ ∀𝑧 𝑧 = 𝑦) → Ⅎ𝑧(𝑤𝑥𝑤𝑦))
11 elequ1 2037 . . . . 5 (𝑤 = 𝑧 → (𝑤𝑥𝑧𝑥))
12 elequ1 2037 . . . . 5 (𝑤 = 𝑧 → (𝑤𝑦𝑧𝑦))
1311, 12bibi12d 334 . . . 4 (𝑤 = 𝑧 → ((𝑤𝑥𝑤𝑦) ↔ (𝑧𝑥𝑧𝑦)))
1413a1i 11 . . 3 ((¬ ∀𝑧 𝑧 = 𝑥 ∧ ¬ ∀𝑧 𝑧 = 𝑦) → (𝑤 = 𝑧 → ((𝑤𝑥𝑤𝑦) ↔ (𝑧𝑥𝑧𝑦))))
153, 10, 14cbvald 2313 . 2 ((¬ ∀𝑧 𝑧 = 𝑥 ∧ ¬ ∀𝑧 𝑧 = 𝑦) → (∀𝑤(𝑤𝑥𝑤𝑦) ↔ ∀𝑧(𝑧𝑥𝑧𝑦)))
16 axext3 2633 . 2 (∀𝑤(𝑤𝑥𝑤𝑦) → 𝑥 = 𝑦)
1715, 16syl6bir 244 1 ((¬ ∀𝑧 𝑧 = 𝑥 ∧ ¬ ∀𝑧 𝑧 = 𝑦) → (∀𝑧(𝑧𝑥𝑧𝑦) → 𝑥 = 𝑦))
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 196   ∧ wa 383  ∀wal 1521  Ⅎwnfc 2780 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1762  ax-4 1777  ax-5 1879  ax-6 1945  ax-7 1981  ax-8 2032  ax-9 2039  ax-10 2059  ax-11 2074  ax-12 2087  ax-13 2282  ax-ext 2631 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-tru 1526  df-ex 1745  df-nf 1750  df-cleq 2644  df-clel 2647  df-nfc 2782 This theorem is referenced by:  axext4dist  31830
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