Mathbox for Alexander van der Vekens < Previous   Next > Nearby theorems Mirrors  >  Home  >  MPE Home  >  Th. List  >   Mathboxes  >  cbvrex2 Structured version   Visualization version   GIF version

Theorem cbvrex2 40477
 Description: Change bound variables of double restricted universal quantification, using implicit substitution, analogous to cbvrex2v 3168. (Contributed by Alexander van der Vekens, 2-Jul-2017.)
Hypotheses
Ref Expression
cbvral2.1 𝑧𝜑
cbvral2.2 𝑥𝜒
cbvral2.3 𝑤𝜒
cbvral2.4 𝑦𝜓
cbvral2.5 (𝑥 = 𝑧 → (𝜑𝜒))
cbvral2.6 (𝑦 = 𝑤 → (𝜒𝜓))
Assertion
Ref Expression
cbvrex2 (∃𝑥𝐴𝑦𝐵 𝜑 ↔ ∃𝑧𝐴𝑤𝐵 𝜓)
Distinct variable groups:   𝑥,𝐴   𝑧,𝐴   𝑥,𝑦,𝐵   𝑦,𝑧,𝐵   𝑤,𝐵
Allowed substitution hints:   𝜑(𝑥,𝑦,𝑧,𝑤)   𝜓(𝑥,𝑦,𝑧,𝑤)   𝜒(𝑥,𝑦,𝑧,𝑤)   𝐴(𝑦,𝑤)

Proof of Theorem cbvrex2
StepHypRef Expression
1 nfcv 2761 . . . 4 𝑧𝐵
2 cbvral2.1 . . . 4 𝑧𝜑
31, 2nfrex 3001 . . 3 𝑧𝑦𝐵 𝜑
4 nfcv 2761 . . . 4 𝑥𝐵
5 cbvral2.2 . . . 4 𝑥𝜒
64, 5nfrex 3001 . . 3 𝑥𝑦𝐵 𝜒
7 cbvral2.5 . . . 4 (𝑥 = 𝑧 → (𝜑𝜒))
87rexbidv 3045 . . 3 (𝑥 = 𝑧 → (∃𝑦𝐵 𝜑 ↔ ∃𝑦𝐵 𝜒))
93, 6, 8cbvrex 3156 . 2 (∃𝑥𝐴𝑦𝐵 𝜑 ↔ ∃𝑧𝐴𝑦𝐵 𝜒)
10 cbvral2.3 . . . 4 𝑤𝜒
11 cbvral2.4 . . . 4 𝑦𝜓
12 cbvral2.6 . . . 4 (𝑦 = 𝑤 → (𝜒𝜓))
1310, 11, 12cbvrex 3156 . . 3 (∃𝑦𝐵 𝜒 ↔ ∃𝑤𝐵 𝜓)
1413rexbii 3034 . 2 (∃𝑧𝐴𝑦𝐵 𝜒 ↔ ∃𝑧𝐴𝑤𝐵 𝜓)
159, 14bitri 264 1 (∃𝑥𝐴𝑦𝐵 𝜑 ↔ ∃𝑧𝐴𝑤𝐵 𝜓)
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 196  Ⅎwnf 1705  ∃wrex 2908 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1719  ax-4 1734  ax-5 1836  ax-6 1885  ax-7 1932  ax-9 1996  ax-10 2016  ax-11 2031  ax-12 2044  ax-13 2245  ax-ext 2601 This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-tru 1483  df-ex 1702  df-nf 1707  df-sb 1878  df-cleq 2614  df-clel 2617  df-nfc 2750  df-ral 2912  df-rex 2913 This theorem is referenced by: (None)
 Copyright terms: Public domain W3C validator