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Theorem bj-cbval2v 31924
 Description: Version of cbval2 2267 with a dv condition, which does not require ax-13 2234. (Contributed by BJ, 16-Jun-2019.) (Proof modification is discouraged.)
Hypotheses
Ref Expression
bj-cbval2v.1 𝑧𝜑
bj-cbval2v.2 𝑤𝜑
bj-cbval2v.3 𝑥𝜓
bj-cbval2v.4 𝑦𝜓
bj-cbval2v.5 ((𝑥 = 𝑧𝑦 = 𝑤) → (𝜑𝜓))
Assertion
Ref Expression
bj-cbval2v (∀𝑥𝑦𝜑 ↔ ∀𝑧𝑤𝜓)
Distinct variable group:   𝑥,𝑦,𝑧,𝑤
Allowed substitution hints:   𝜑(𝑥,𝑦,𝑧,𝑤)   𝜓(𝑥,𝑦,𝑧,𝑤)

Proof of Theorem bj-cbval2v
StepHypRef Expression
1 bj-cbval2v.1 . . 3 𝑧𝜑
21nfal 2139 . 2 𝑧𝑦𝜑
3 bj-cbval2v.3 . . 3 𝑥𝜓
43nfal 2139 . 2 𝑥𝑤𝜓
5 nfv 1830 . . . . . 6 𝑤 𝑥 = 𝑧
6 bj-cbval2v.2 . . . . . 6 𝑤𝜑
75, 6nfim 1813 . . . . 5 𝑤(𝑥 = 𝑧𝜑)
8 nfv 1830 . . . . . 6 𝑦 𝑥 = 𝑧
9 bj-cbval2v.4 . . . . . 6 𝑦𝜓
108, 9nfim 1813 . . . . 5 𝑦(𝑥 = 𝑧𝜓)
11 bj-cbval2v.5 . . . . . . 7 ((𝑥 = 𝑧𝑦 = 𝑤) → (𝜑𝜓))
1211expcom 450 . . . . . 6 (𝑦 = 𝑤 → (𝑥 = 𝑧 → (𝜑𝜓)))
1312pm5.74d 261 . . . . 5 (𝑦 = 𝑤 → ((𝑥 = 𝑧𝜑) ↔ (𝑥 = 𝑧𝜓)))
147, 10, 13cbvalv1 2163 . . . 4 (∀𝑦(𝑥 = 𝑧𝜑) ↔ ∀𝑤(𝑥 = 𝑧𝜓))
15 19.21v 1855 . . . 4 (∀𝑦(𝑥 = 𝑧𝜑) ↔ (𝑥 = 𝑧 → ∀𝑦𝜑))
16 19.21v 1855 . . . 4 (∀𝑤(𝑥 = 𝑧𝜓) ↔ (𝑥 = 𝑧 → ∀𝑤𝜓))
1714, 15, 163bitr3i 289 . . 3 ((𝑥 = 𝑧 → ∀𝑦𝜑) ↔ (𝑥 = 𝑧 → ∀𝑤𝜓))
1817pm5.74ri 260 . 2 (𝑥 = 𝑧 → (∀𝑦𝜑 ↔ ∀𝑤𝜓))
192, 4, 18cbvalv1 2163 1 (∀𝑥𝑦𝜑 ↔ ∀𝑧𝑤𝜓)
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 195   ∧ wa 383  ∀wal 1473  Ⅎwnf 1699 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-10 2006  ax-11 2021  ax-12 2034 This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-tru 1478  df-ex 1696  df-nf 1701 This theorem is referenced by:  bj-cbvex2v  31925  bj-cbval2vv  31926
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