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Theorem cbvriota 5840
Description: Change bound variable in a restricted description binder. (Contributed by NM, 18-Mar-2013.) (Revised by Mario Carneiro, 15-Oct-2016.)
Hypotheses
Ref Expression
cbvriota.1 𝑦𝜑
cbvriota.2 𝑥𝜓
cbvriota.3 (𝑥 = 𝑦 → (𝜑𝜓))
Assertion
Ref Expression
cbvriota (𝑥𝐴 𝜑) = (𝑦𝐴 𝜓)
Distinct variable groups:   𝑥,𝐴   𝑦,𝐴
Allowed substitution hints:   𝜑(𝑥,𝑦)   𝜓(𝑥,𝑦)

Proof of Theorem cbvriota
Dummy variable 𝑧 is distinct from all other variables.
StepHypRef Expression
1 eleq1 2240 . . . . 5 (𝑥 = 𝑧 → (𝑥𝐴𝑧𝐴))
2 sbequ12 1771 . . . . 5 (𝑥 = 𝑧 → (𝜑 ↔ [𝑧 / 𝑥]𝜑))
31, 2anbi12d 473 . . . 4 (𝑥 = 𝑧 → ((𝑥𝐴𝜑) ↔ (𝑧𝐴 ∧ [𝑧 / 𝑥]𝜑)))
4 nfv 1528 . . . 4 𝑧(𝑥𝐴𝜑)
5 nfv 1528 . . . . 5 𝑥 𝑧𝐴
6 nfs1v 1939 . . . . 5 𝑥[𝑧 / 𝑥]𝜑
75, 6nfan 1565 . . . 4 𝑥(𝑧𝐴 ∧ [𝑧 / 𝑥]𝜑)
83, 4, 7cbviota 5183 . . 3 (℩𝑥(𝑥𝐴𝜑)) = (℩𝑧(𝑧𝐴 ∧ [𝑧 / 𝑥]𝜑))
9 eleq1 2240 . . . . 5 (𝑧 = 𝑦 → (𝑧𝐴𝑦𝐴))
10 sbequ 1840 . . . . . 6 (𝑧 = 𝑦 → ([𝑧 / 𝑥]𝜑 ↔ [𝑦 / 𝑥]𝜑))
11 cbvriota.2 . . . . . . 7 𝑥𝜓
12 cbvriota.3 . . . . . . 7 (𝑥 = 𝑦 → (𝜑𝜓))
1311, 12sbie 1791 . . . . . 6 ([𝑦 / 𝑥]𝜑𝜓)
1410, 13bitrdi 196 . . . . 5 (𝑧 = 𝑦 → ([𝑧 / 𝑥]𝜑𝜓))
159, 14anbi12d 473 . . . 4 (𝑧 = 𝑦 → ((𝑧𝐴 ∧ [𝑧 / 𝑥]𝜑) ↔ (𝑦𝐴𝜓)))
16 nfv 1528 . . . . 5 𝑦 𝑧𝐴
17 cbvriota.1 . . . . . 6 𝑦𝜑
1817nfsb 1946 . . . . 5 𝑦[𝑧 / 𝑥]𝜑
1916, 18nfan 1565 . . . 4 𝑦(𝑧𝐴 ∧ [𝑧 / 𝑥]𝜑)
20 nfv 1528 . . . 4 𝑧(𝑦𝐴𝜓)
2115, 19, 20cbviota 5183 . . 3 (℩𝑧(𝑧𝐴 ∧ [𝑧 / 𝑥]𝜑)) = (℩𝑦(𝑦𝐴𝜓))
228, 21eqtri 2198 . 2 (℩𝑥(𝑥𝐴𝜑)) = (℩𝑦(𝑦𝐴𝜓))
23 df-riota 5830 . 2 (𝑥𝐴 𝜑) = (℩𝑥(𝑥𝐴𝜑))
24 df-riota 5830 . 2 (𝑦𝐴 𝜓) = (℩𝑦(𝑦𝐴𝜓))
2522, 23, 243eqtr4i 2208 1 (𝑥𝐴 𝜑) = (𝑦𝐴 𝜓)
Colors of variables: wff set class
Syntax hints:  wi 4  wa 104  wb 105   = wceq 1353  wnf 1460  [wsb 1762  wcel 2148  cio 5176  crio 5829
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 709  ax-5 1447  ax-7 1448  ax-gen 1449  ax-ie1 1493  ax-ie2 1494  ax-8 1504  ax-10 1505  ax-11 1506  ax-i12 1507  ax-bndl 1509  ax-4 1510  ax-17 1526  ax-i9 1530  ax-ial 1534  ax-i5r 1535  ax-ext 2159
This theorem depends on definitions:  df-bi 117  df-tru 1356  df-nf 1461  df-sb 1763  df-clab 2164  df-cleq 2170  df-clel 2173  df-nfc 2308  df-rex 2461  df-sn 3598  df-uni 3810  df-iota 5178  df-riota 5830
This theorem is referenced by:  cbvriotav  5841
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