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Theorem cbvmpt 3878
Description: Rule to change the bound variable in a maps-to function, using implicit substitution. This version has bound-variable hypotheses in place of distinct variable conditions. (Contributed by NM, 11-Sep-2011.)
Hypotheses
Ref Expression
cbvmpt.1 𝑦𝐵
cbvmpt.2 𝑥𝐶
cbvmpt.3 (𝑥 = 𝑦𝐵 = 𝐶)
Assertion
Ref Expression
cbvmpt (𝑥𝐴𝐵) = (𝑦𝐴𝐶)
Distinct variable groups:   𝑥,𝐴   𝑦,𝐴
Allowed substitution hints:   𝐵(𝑥,𝑦)   𝐶(𝑥,𝑦)

Proof of Theorem cbvmpt
Dummy variables 𝑧 𝑤 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 nfv 1437 . . . 4 𝑤(𝑥𝐴𝑧 = 𝐵)
2 nfv 1437 . . . . 5 𝑥 𝑤𝐴
3 nfs1v 1831 . . . . 5 𝑥[𝑤 / 𝑥]𝑧 = 𝐵
42, 3nfan 1473 . . . 4 𝑥(𝑤𝐴 ∧ [𝑤 / 𝑥]𝑧 = 𝐵)
5 eleq1 2116 . . . . 5 (𝑥 = 𝑤 → (𝑥𝐴𝑤𝐴))
6 sbequ12 1670 . . . . 5 (𝑥 = 𝑤 → (𝑧 = 𝐵 ↔ [𝑤 / 𝑥]𝑧 = 𝐵))
75, 6anbi12d 450 . . . 4 (𝑥 = 𝑤 → ((𝑥𝐴𝑧 = 𝐵) ↔ (𝑤𝐴 ∧ [𝑤 / 𝑥]𝑧 = 𝐵)))
81, 4, 7cbvopab1 3857 . . 3 {⟨𝑥, 𝑧⟩ ∣ (𝑥𝐴𝑧 = 𝐵)} = {⟨𝑤, 𝑧⟩ ∣ (𝑤𝐴 ∧ [𝑤 / 𝑥]𝑧 = 𝐵)}
9 nfv 1437 . . . . 5 𝑦 𝑤𝐴
10 cbvmpt.1 . . . . . . 7 𝑦𝐵
1110nfeq2 2205 . . . . . 6 𝑦 𝑧 = 𝐵
1211nfsb 1838 . . . . 5 𝑦[𝑤 / 𝑥]𝑧 = 𝐵
139, 12nfan 1473 . . . 4 𝑦(𝑤𝐴 ∧ [𝑤 / 𝑥]𝑧 = 𝐵)
14 nfv 1437 . . . 4 𝑤(𝑦𝐴𝑧 = 𝐶)
15 eleq1 2116 . . . . 5 (𝑤 = 𝑦 → (𝑤𝐴𝑦𝐴))
16 sbequ 1737 . . . . . 6 (𝑤 = 𝑦 → ([𝑤 / 𝑥]𝑧 = 𝐵 ↔ [𝑦 / 𝑥]𝑧 = 𝐵))
17 cbvmpt.2 . . . . . . . 8 𝑥𝐶
1817nfeq2 2205 . . . . . . 7 𝑥 𝑧 = 𝐶
19 cbvmpt.3 . . . . . . . 8 (𝑥 = 𝑦𝐵 = 𝐶)
2019eqeq2d 2067 . . . . . . 7 (𝑥 = 𝑦 → (𝑧 = 𝐵𝑧 = 𝐶))
2118, 20sbie 1690 . . . . . 6 ([𝑦 / 𝑥]𝑧 = 𝐵𝑧 = 𝐶)
2216, 21syl6bb 189 . . . . 5 (𝑤 = 𝑦 → ([𝑤 / 𝑥]𝑧 = 𝐵𝑧 = 𝐶))
2315, 22anbi12d 450 . . . 4 (𝑤 = 𝑦 → ((𝑤𝐴 ∧ [𝑤 / 𝑥]𝑧 = 𝐵) ↔ (𝑦𝐴𝑧 = 𝐶)))
2413, 14, 23cbvopab1 3857 . . 3 {⟨𝑤, 𝑧⟩ ∣ (𝑤𝐴 ∧ [𝑤 / 𝑥]𝑧 = 𝐵)} = {⟨𝑦, 𝑧⟩ ∣ (𝑦𝐴𝑧 = 𝐶)}
258, 24eqtri 2076 . 2 {⟨𝑥, 𝑧⟩ ∣ (𝑥𝐴𝑧 = 𝐵)} = {⟨𝑦, 𝑧⟩ ∣ (𝑦𝐴𝑧 = 𝐶)}
26 df-mpt 3847 . 2 (𝑥𝐴𝐵) = {⟨𝑥, 𝑧⟩ ∣ (𝑥𝐴𝑧 = 𝐵)}
27 df-mpt 3847 . 2 (𝑦𝐴𝐶) = {⟨𝑦, 𝑧⟩ ∣ (𝑦𝐴𝑧 = 𝐶)}
2825, 26, 273eqtr4i 2086 1 (𝑥𝐴𝐵) = (𝑦𝐴𝐶)
Colors of variables: wff set class
Syntax hints:  wi 4  wa 101   = wceq 1259  wcel 1409  [wsb 1661  wnfc 2181  {copab 3844  cmpt 3845
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-ia3 105  ax-io 640  ax-5 1352  ax-7 1353  ax-gen 1354  ax-ie1 1398  ax-ie2 1399  ax-8 1411  ax-10 1412  ax-11 1413  ax-i12 1414  ax-bndl 1415  ax-4 1416  ax-17 1435  ax-i9 1439  ax-ial 1443  ax-i5r 1444  ax-ext 2038
This theorem depends on definitions:  df-bi 114  df-3an 898  df-tru 1262  df-nf 1366  df-sb 1662  df-clab 2043  df-cleq 2049  df-clel 2052  df-nfc 2183  df-v 2576  df-un 2949  df-sn 3408  df-pr 3409  df-op 3411  df-opab 3846  df-mpt 3847
This theorem is referenced by:  cbvmptv  3879  dffn5imf  5255  fvmpts  5277  fvmpt2  5281  mptfvex  5283  fmptcof  5358  fmptcos  5359  fliftfuns  5465  offval2  5753  qliftfuns  6220
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