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Theorem r19.32vdc 2512
Description: Theorem 19.32 of [Margaris] p. 90 with restricted quantifiers, where 𝜑 is decidable. (Contributed by Jim Kingdon, 4-Jun-2018.)
Assertion
Ref Expression
r19.32vdc (DECID 𝜑 → (∀𝑥𝐴 (𝜑𝜓) ↔ (𝜑 ∨ ∀𝑥𝐴 𝜓)))
Distinct variable group:   𝜑,𝑥
Allowed substitution hints:   𝜓(𝑥)   𝐴(𝑥)

Proof of Theorem r19.32vdc
StepHypRef Expression
1 r19.21v 2446 . . 3 (∀𝑥𝐴𝜑𝜓) ↔ (¬ 𝜑 → ∀𝑥𝐴 𝜓))
21a1i 9 . 2 (DECID 𝜑 → (∀𝑥𝐴𝜑𝜓) ↔ (¬ 𝜑 → ∀𝑥𝐴 𝜓)))
3 dfordc 827 . . 3 (DECID 𝜑 → ((𝜑𝜓) ↔ (¬ 𝜑𝜓)))
43ralbidv 2376 . 2 (DECID 𝜑 → (∀𝑥𝐴 (𝜑𝜓) ↔ ∀𝑥𝐴𝜑𝜓)))
5 dfordc 827 . 2 (DECID 𝜑 → ((𝜑 ∨ ∀𝑥𝐴 𝜓) ↔ (¬ 𝜑 → ∀𝑥𝐴 𝜓)))
62, 4, 53bitr4d 218 1 (DECID 𝜑 → (∀𝑥𝐴 (𝜑𝜓) ↔ (𝜑 ∨ ∀𝑥𝐴 𝜓)))
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4  wb 103  wo 662  DECID wdc 778  wral 2355
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-in1 577  ax-in2 578  ax-io 663  ax-5 1379  ax-gen 1381  ax-4 1443  ax-17 1462  ax-ial 1470  ax-i5r 1471
This theorem depends on definitions:  df-bi 115  df-dc 779  df-nf 1393  df-ral 2360
This theorem is referenced by: (None)
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