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Theorem csbafv12g 28105
Description: Move class substitution in and out of a function value, analogous to csbfv12g 5551, with a direct proof proposed by Mario Carneiro, analogous to csbovg 5905. (Contributed by Alexander van der Vekens, 23-Jul-2017.)
Assertion
Ref Expression
csbafv12g  |-  ( A  e.  V  ->  [_ A  /  x ]_ ( F''' B )  =  (
[_ A  /  x ]_ F''' [_ A  /  x ]_ B ) )

Proof of Theorem csbafv12g
Dummy variable  y is distinct from all other variables.
StepHypRef Expression
1 csbeq1 3097 . . 3  |-  ( y  =  A  ->  [_ y  /  x ]_ ( F''' B )  =  [_ A  /  x ]_ ( F''' B ) )
2 csbeq1 3097 . . . 4  |-  ( y  =  A  ->  [_ y  /  x ]_ F  = 
[_ A  /  x ]_ F )
3 csbeq1 3097 . . . 4  |-  ( y  =  A  ->  [_ y  /  x ]_ B  = 
[_ A  /  x ]_ B )
42, 3afveq12d 28101 . . 3  |-  ( y  =  A  ->  ( [_ y  /  x ]_ F''' [_ y  /  x ]_ B )  =  (
[_ A  /  x ]_ F''' [_ A  /  x ]_ B ) )
51, 4eqeq12d 2310 . 2  |-  ( y  =  A  ->  ( [_ y  /  x ]_ ( F''' B )  =  (
[_ y  /  x ]_ F''' [_ y  /  x ]_ B )  <->  [_ A  /  x ]_ ( F''' B )  =  ( [_ A  /  x ]_ F''' [_ A  /  x ]_ B ) ) )
6 vex 2804 . . 3  |-  y  e. 
_V
7 nfcsb1v 3126 . . . 4  |-  F/_ x [_ y  /  x ]_ F
8 nfcsb1v 3126 . . . 4  |-  F/_ x [_ y  /  x ]_ B
97, 8nfafv 28104 . . 3  |-  F/_ x
( [_ y  /  x ]_ F''' [_ y  /  x ]_ B )
10 csbeq1a 3102 . . . 4  |-  ( x  =  y  ->  F  =  [_ y  /  x ]_ F )
11 csbeq1a 3102 . . . 4  |-  ( x  =  y  ->  B  =  [_ y  /  x ]_ B )
1210, 11afveq12d 28101 . . 3  |-  ( x  =  y  ->  ( F''' B )  =  (
[_ y  /  x ]_ F''' [_ y  /  x ]_ B ) )
136, 9, 12csbief 3135 . 2  |-  [_ y  /  x ]_ ( F''' B )  =  (
[_ y  /  x ]_ F''' [_ y  /  x ]_ B )
145, 13vtoclg 2856 1  |-  ( A  e.  V  ->  [_ A  /  x ]_ ( F''' B )  =  (
[_ A  /  x ]_ F''' [_ A  /  x ]_ B ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    = wceq 1632    e. wcel 1696   [_csb 3094  '''cafv 28075
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1536  ax-5 1547  ax-17 1606  ax-9 1644  ax-8 1661  ax-6 1715  ax-7 1720  ax-11 1727  ax-12 1878  ax-ext 2277
This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-3an 936  df-tru 1310  df-ex 1532  df-nf 1535  df-sb 1639  df-clab 2283  df-cleq 2289  df-clel 2292  df-nfc 2421  df-ral 2561  df-rex 2562  df-rab 2565  df-v 2803  df-sbc 3005  df-csb 3095  df-dif 3168  df-un 3170  df-in 3172  df-ss 3179  df-nul 3469  df-if 3579  df-sn 3659  df-pr 3660  df-op 3662  df-uni 3844  df-br 4040  df-opab 4094  df-xp 4711  df-rel 4712  df-cnv 4713  df-co 4714  df-dm 4715  df-res 4717  df-iota 5235  df-fun 5273  df-fv 5279  df-dfat 28077  df-afv 28078
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