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Theorem csbvarg 3030
Description: The proper substitution of a class for setvar variable results in the class (if the class exists). (Contributed by NM, 10-Nov-2005.)
Assertion
Ref Expression
csbvarg (𝐴𝑉𝐴 / 𝑥𝑥 = 𝐴)

Proof of Theorem csbvarg
Dummy variables 𝑦 𝑧 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 elex 2697 . 2 (𝐴𝑉𝐴 ∈ V)
2 vex 2689 . . . . . 6 𝑦 ∈ V
3 df-csb 3004 . . . . . . 7 𝑦 / 𝑥𝑥 = {𝑧[𝑦 / 𝑥]𝑧𝑥}
4 sbcel2gv 2972 . . . . . . . 8 (𝑦 ∈ V → ([𝑦 / 𝑥]𝑧𝑥𝑧𝑦))
54abbi1dv 2259 . . . . . . 7 (𝑦 ∈ V → {𝑧[𝑦 / 𝑥]𝑧𝑥} = 𝑦)
63, 5syl5eq 2184 . . . . . 6 (𝑦 ∈ V → 𝑦 / 𝑥𝑥 = 𝑦)
72, 6ax-mp 5 . . . . 5 𝑦 / 𝑥𝑥 = 𝑦
87csbeq2i 3029 . . . 4 𝐴 / 𝑦𝑦 / 𝑥𝑥 = 𝐴 / 𝑦𝑦
9 csbco 3013 . . . 4 𝐴 / 𝑦𝑦 / 𝑥𝑥 = 𝐴 / 𝑥𝑥
10 df-csb 3004 . . . 4 𝐴 / 𝑦𝑦 = {𝑧[𝐴 / 𝑦]𝑧𝑦}
118, 9, 103eqtr3i 2168 . . 3 𝐴 / 𝑥𝑥 = {𝑧[𝐴 / 𝑦]𝑧𝑦}
12 sbcel2gv 2972 . . . 4 (𝐴 ∈ V → ([𝐴 / 𝑦]𝑧𝑦𝑧𝐴))
1312abbi1dv 2259 . . 3 (𝐴 ∈ V → {𝑧[𝐴 / 𝑦]𝑧𝑦} = 𝐴)
1411, 13syl5eq 2184 . 2 (𝐴 ∈ V → 𝐴 / 𝑥𝑥 = 𝐴)
151, 14syl 14 1 (𝐴𝑉𝐴 / 𝑥𝑥 = 𝐴)
Colors of variables: wff set class
Syntax hints:  wi 4   = wceq 1331  wcel 1480  {cab 2125  Vcvv 2686  [wsbc 2909  csb 3003
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 698  ax-5 1423  ax-7 1424  ax-gen 1425  ax-ie1 1469  ax-ie2 1470  ax-8 1482  ax-10 1483  ax-11 1484  ax-i12 1485  ax-bndl 1486  ax-4 1487  ax-17 1506  ax-i9 1510  ax-ial 1514  ax-i5r 1515  ax-ext 2121
This theorem depends on definitions:  df-bi 116  df-tru 1334  df-nf 1437  df-sb 1736  df-clab 2126  df-cleq 2132  df-clel 2135  df-nfc 2270  df-v 2688  df-sbc 2910  df-csb 3004
This theorem is referenced by:  sbccsb2g  3032  csbfvg  5459  f1od2  6132  bj-sels  13171
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