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Theorem rexxfr2d 4197
Description: Transfer universal quantification from a variable 𝑥 to another variable 𝑦 contained in expression 𝐴. (Contributed by Mario Carneiro, 20-Aug-2014.) (Proof shortened by Mario Carneiro, 19-Nov-2016.)
Hypotheses
Ref Expression
ralxfr2d.1 ((𝜑𝑦𝐶) → 𝐴𝑉)
ralxfr2d.2 (𝜑 → (𝑥𝐵 ↔ ∃𝑦𝐶 𝑥 = 𝐴))
ralxfr2d.3 ((𝜑𝑥 = 𝐴) → (𝜓𝜒))
Assertion
Ref Expression
rexxfr2d (𝜑 → (∃𝑥𝐵 𝜓 ↔ ∃𝑦𝐶 𝜒))
Distinct variable groups:   𝑥,𝐴   𝑥,𝑦,𝐵   𝑥,𝐶   𝜒,𝑥   𝜑,𝑥,𝑦   𝜓,𝑦
Allowed substitution hints:   𝜓(𝑥)   𝜒(𝑦)   𝐴(𝑦)   𝐶(𝑦)   𝑉(𝑥,𝑦)

Proof of Theorem rexxfr2d
StepHypRef Expression
1 ralxfr2d.1 . . . 4 ((𝜑𝑦𝐶) → 𝐴𝑉)
2 elisset 2568 . . . 4 (𝐴𝑉 → ∃𝑥 𝑥 = 𝐴)
31, 2syl 14 . . 3 ((𝜑𝑦𝐶) → ∃𝑥 𝑥 = 𝐴)
4 ralxfr2d.2 . . . . . . . 8 (𝜑 → (𝑥𝐵 ↔ ∃𝑦𝐶 𝑥 = 𝐴))
54biimprd 147 . . . . . . 7 (𝜑 → (∃𝑦𝐶 𝑥 = 𝐴𝑥𝐵))
6 r19.23v 2425 . . . . . . 7 (∀𝑦𝐶 (𝑥 = 𝐴𝑥𝐵) ↔ (∃𝑦𝐶 𝑥 = 𝐴𝑥𝐵))
75, 6sylibr 137 . . . . . 6 (𝜑 → ∀𝑦𝐶 (𝑥 = 𝐴𝑥𝐵))
87r19.21bi 2407 . . . . 5 ((𝜑𝑦𝐶) → (𝑥 = 𝐴𝑥𝐵))
9 eleq1 2100 . . . . 5 (𝑥 = 𝐴 → (𝑥𝐵𝐴𝐵))
108, 9mpbidi 140 . . . 4 ((𝜑𝑦𝐶) → (𝑥 = 𝐴𝐴𝐵))
1110exlimdv 1700 . . 3 ((𝜑𝑦𝐶) → (∃𝑥 𝑥 = 𝐴𝐴𝐵))
123, 11mpd 13 . 2 ((𝜑𝑦𝐶) → 𝐴𝐵)
134biimpa 280 . 2 ((𝜑𝑥𝐵) → ∃𝑦𝐶 𝑥 = 𝐴)
14 ralxfr2d.3 . 2 ((𝜑𝑥 = 𝐴) → (𝜓𝜒))
1512, 13, 14rexxfrd 4195 1 (𝜑 → (∃𝑥𝐵 𝜓 ↔ ∃𝑦𝐶 𝜒))
Colors of variables: wff set class
Syntax hints:  wi 4  wa 97  wb 98   = wceq 1243  wex 1381  wcel 1393  wral 2306  wrex 2307
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 630  ax-5 1336  ax-7 1337  ax-gen 1338  ax-ie1 1382  ax-ie2 1383  ax-8 1395  ax-10 1396  ax-11 1397  ax-i12 1398  ax-bndl 1399  ax-4 1400  ax-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428  ax-ext 2022
This theorem depends on definitions:  df-bi 110  df-tru 1246  df-nf 1350  df-sb 1646  df-clab 2027  df-cleq 2033  df-clel 2036  df-nfc 2167  df-ral 2311  df-rex 2312  df-v 2559
This theorem is referenced by:  rexrn  5304  rexima  5394
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