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Theorem spc2d 29441
 Description: Specialization with 2 quantifiers, using implicit substitution. (Contributed by Thierry Arnoux, 23-Aug-2017.)
Hypotheses
Ref Expression
spc2ed.x 𝑥𝜒
spc2ed.y 𝑦𝜒
spc2ed.1 ((𝜑 ∧ (𝑥 = 𝐴𝑦 = 𝐵)) → (𝜓𝜒))
Assertion
Ref Expression
spc2d ((𝜑 ∧ (𝐴𝑉𝐵𝑊)) → (∀𝑥𝑦𝜓𝜒))
Distinct variable groups:   𝑥,𝑦,𝐴   𝑥,𝐵,𝑦   𝜑,𝑥,𝑦
Allowed substitution hints:   𝜓(𝑥,𝑦)   𝜒(𝑥,𝑦)   𝑉(𝑥,𝑦)   𝑊(𝑥,𝑦)

Proof of Theorem spc2d
StepHypRef Expression
1 2nalexn 1795 . . 3 (¬ ∀𝑥𝑦𝜓 ↔ ∃𝑥𝑦 ¬ 𝜓)
21con1bii 345 . 2 (¬ ∃𝑥𝑦 ¬ 𝜓 ↔ ∀𝑥𝑦𝜓)
3 spc2ed.x . . . . 5 𝑥𝜒
43nfn 1824 . . . 4 𝑥 ¬ 𝜒
5 spc2ed.y . . . . 5 𝑦𝜒
65nfn 1824 . . . 4 𝑦 ¬ 𝜒
7 spc2ed.1 . . . . 5 ((𝜑 ∧ (𝑥 = 𝐴𝑦 = 𝐵)) → (𝜓𝜒))
87notbid 307 . . . 4 ((𝜑 ∧ (𝑥 = 𝐴𝑦 = 𝐵)) → (¬ 𝜓 ↔ ¬ 𝜒))
94, 6, 8spc2ed 29440 . . 3 ((𝜑 ∧ (𝐴𝑉𝐵𝑊)) → (¬ 𝜒 → ∃𝑥𝑦 ¬ 𝜓))
109con1d 139 . 2 ((𝜑 ∧ (𝐴𝑉𝐵𝑊)) → (¬ ∃𝑥𝑦 ¬ 𝜓𝜒))
112, 10syl5bir 233 1 ((𝜑 ∧ (𝐴𝑉𝐵𝑊)) → (∀𝑥𝑦𝜓𝜒))
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 196   ∧ wa 383  ∀wal 1521   = wceq 1523  ∃wex 1744  Ⅎwnf 1748   ∈ wcel 2030 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-9 2039  ax-10 2059  ax-11 2074  ax-12 2087  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-sb 1938  df-clab 2638  df-cleq 2644  df-clel 2647  df-v 3233 This theorem is referenced by: (None)
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