Theorem sbceqg 3023

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 2916	. . 3 |- ( z = A -> ( [ z / x ] B = C <-> [. A / x ]. B = C ) )
2		dfsbcq2 2916	. . . . 5 |- ( z = A -> ( [ z / x ] y e. B <-> [. A / x ]. y e. B ) )
3	2	abbidv 2258	. . . 4 |- ( z = A -> { y | [ z / x ] y e. B } = { y | [. A / x ]. y e. B } )
4		dfsbcq2 2916	. . . . 5 |- ( z = A -> ( [ z / x ] y e. C <-> [. A / x ]. y e. C ) )
5	4	abbidv 2258	. . . 4 |- ( z = A -> { y | [ z / x ] y e. C } = { y | [. A / x ]. y e. C } )
6	3, 5	eqeq12d 2155	. . 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 1913	. . . . . 6 |- F/ x [ z / x ] y e. B
8	7	nfab 2287	. . . . 5 |- F/_ x { y | [ z / x ] y e. B }
9		nfs1v 1913	. . . . . 6 |- F/ x [ z / x ] y e. C
10	9	nfab 2287	. . . . 5 |- F/_ x { y | [ z / x ] y e. C }
11	8, 10	nfeq 2290	. . . 4 |- F/ x { y | [ z / x ] y e. B } = { y | [ z / x ] y e. C }
12		sbab 2268	. . . . 5 |- ( x = z -> B = { y | [ z / x ] y e. B } )
13		sbab 2268	. . . . 5 |- ( x = z -> C = { y | [ z / x ] y e. C } )
14	12, 13	eqeq12d 2155	. . . 4 |- ( x = z -> ( B = C <-> { y | [ z / x ] y e. B } = { y | [ z / x ] y e. C } ) )
15	11, 14	sbie 1765	. . 3 |- ( [ z / x ] B = C <-> { y | [ z / x ] y e. B } = { y | [ z / x ] y e. C } )
16	1, 6, 15	vtoclbg 2750	. 2 |- ( A e. V -> ( [. A / x ]. B = C <-> { y | [. A / x ]. y e. B } = { y | [. A / x ]. y e. C } ) )
17		df-csb 3008	. . 3 |- [_ A / x ]_ B = { y | [. A / x ]. y e. B }
18		df-csb 3008	. . 3 |- [_ A / x ]_ C = { y | [. A / x ]. y e. C }
19	17, 18	eqeq12i 2154	. 2 |- ( [_ A / x ]_ B = [_ A / x ]_ C <-> { y | [. A / x ]. y e. B } = { y | [. A / x ]. y e. C } )
20	16, 19	syl6bbr 197	1 |- ( A e. V -> ( [. A / x ]. B = C <-> [_ A / x ]_ B = [_ A / x ]_ C ) )

Syntax hints:   -> wi 4   <-> wb 104   = wceq 1332   e. wcel 1481   [wsb 1736   {cab 2126   [.wsbc 2913   [_csb 3007

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 1424  ax-7 1425  ax-gen 1426  ax-ie1 1470  ax-ie2 1471  ax-8 1483  ax-10 1484  ax-11 1485  ax-i12 1486  ax-bndl 1487  ax-4 1488  ax-17 1507  ax-i9 1511  ax-ial 1515  ax-i5r 1516  ax-ext 2122

This theorem depends on definitions:  df-bi 116  df-tru 1335  df-nf 1438  df-sb 1737  df-clab 2127  df-cleq 2133  df-clel 2136  df-nfc 2271  df-v 2691  df-sbc 2914  df-csb 3008

This theorem is referenced by:  sbcne12g  3025  sbceq1g  3027  sbceq2g  3029  sbcfng  5278