Theorem sbceqg 3047

Description: Distribute proper substitution through an equality relation. (Contributed by NM, 10-Nov-2005.) (Proof shortened by Andrew Salmon, 29-Jun-2011.)

Assertion

Ref	Expression
sbceqg	|- ( A e. V -> ( [. A / x ]. B = C <-> [_ A / x ]_ B = [_ A / x ]_ C ) )

Proof of Theorem sbceqg

Dummy variables y z are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		dfsbcq2 2940	. . 3 |- ( z = A -> ( [ z / x ] B = C <-> [. A / x ]. B = C ) )
2		dfsbcq2 2940	. . . . 5 |- ( z = A -> ( [ z / x ] y e. B <-> [. A / x ]. y e. B ) )
3	2	abbidv 2275	. . . 4 |- ( z = A -> { y | [ z / x ] y e. B } = { y | [. A / x ]. y e. B } )
4		dfsbcq2 2940	. . . . 5 |- ( z = A -> ( [ z / x ] y e. C <-> [. A / x ]. y e. C ) )
5	4	abbidv 2275	. . . 4 |- ( z = A -> { y | [ z / x ] y e. C } = { y | [. A / x ]. y e. C } )
6	3, 5	eqeq12d 2172	. . 3 |- ( z = A -> ( { y | [ z / x ] y e. B } = { y | [ z / x ] y e. C } <-> { y | [. A / x ]. y e. B } = { y | [. A / x ]. y e. C } ) )
7		nfs1v 1919	. . . . . 6 |- F/ x [ z / x ] y e. B
8	7	nfab 2304	. . . . 5 |- F/_ x { y | [ z / x ] y e. B }
9		nfs1v 1919	. . . . . 6 |- F/ x [ z / x ] y e. C
10	9	nfab 2304	. . . . 5 |- F/_ x { y | [ z / x ] y e. C }
11	8, 10	nfeq 2307	. . . 4 |- F/ x { y | [ z / x ] y e. B } = { y | [ z / x ] y e. C }
12		sbab 2285	. . . . 5 |- ( x = z -> B = { y | [ z / x ] y e. B } )
13		sbab 2285	. . . . 5 |- ( x = z -> C = { y | [ z / x ] y e. C } )
14	12, 13	eqeq12d 2172	. . . 4 |- ( x = z -> ( B = C <-> { y | [ z / x ] y e. B } = { y | [ z / x ] y e. C } ) )
15	11, 14	sbie 1771	. . 3 |- ( [ z / x ] B = C <-> { y | [ z / x ] y e. B } = { y | [ z / x ] y e. C } )
16	1, 6, 15	vtoclbg 2773	. 2 |- ( A e. V -> ( [. A / x ]. B = C <-> { y | [. A / x ]. y e. B } = { y | [. A / x ]. y e. C } ) )
17		df-csb 3032	. . 3 |- [_ A / x ]_ B = { y | [. A / x ]. y e. B }
18		df-csb 3032	. . 3 |- [_ A / x ]_ C = { y | [. A / x ]. y e. C }
19	17, 18	eqeq12i 2171	. 2 |- ( [_ A / x ]_ B = [_ A / x ]_ C <-> { y | [. A / x ]. y e. B } = { y | [. A / x ]. y e. C } )
20	16, 19	bitr4di 197	1 |- ( A e. V -> ( [. A / x ]. B = C <-> [_ A / x ]_ B = [_ A / x ]_ C ) )

Syntax hints:   -> wi 4   <-> wb 104   = wceq 1335   [wsb 1742   e. wcel 2128   {cab 2143   [.wsbc 2937   [_csb 3031

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 699  ax-5 1427  ax-7 1428  ax-gen 1429  ax-ie1 1473  ax-ie2 1474  ax-8 1484  ax-10 1485  ax-11 1486  ax-i12 1487  ax-bndl 1489  ax-4 1490  ax-17 1506  ax-i9 1510  ax-ial 1514  ax-i5r 1515  ax-ext 2139

This theorem depends on definitions:  df-bi 116  df-tru 1338  df-nf 1441  df-sb 1743  df-clab 2144  df-cleq 2150  df-clel 2153  df-nfc 2288  df-v 2714  df-sbc 2938  df-csb 3032

This theorem is referenced by:  sbcne12g  3049  sbceq1g  3051  sbceq2g  3053  sbcfng  5317  fprodmodd  11538