Theorem sbceqg 2947

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 2843	. . 3 |- ( z = A -> ( [ z / x ] B = C <-> [. A / x ]. B = C ) )
2		dfsbcq2 2843	. . . . 5 |- ( z = A -> ( [ z / x ] y e. B <-> [. A / x ]. y e. B ) )
3	2	abbidv 2205	. . . 4 |- ( z = A -> { y | [ z / x ] y e. B } = { y | [. A / x ]. y e. B } )
4		dfsbcq2 2843	. . . . 5 |- ( z = A -> ( [ z / x ] y e. C <-> [. A / x ]. y e. C ) )
5	4	abbidv 2205	. . . 4 |- ( z = A -> { y | [ z / x ] y e. C } = { y | [. A / x ]. y e. C } )
6	3, 5	eqeq12d 2102	. . 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 1863	. . . . . 6 |- F/ x [ z / x ] y e. B
8	7	nfab 2233	. . . . 5 |- F/_ x { y | [ z / x ] y e. B }
9		nfs1v 1863	. . . . . 6 |- F/ x [ z / x ] y e. C
10	9	nfab 2233	. . . . 5 |- F/_ x { y | [ z / x ] y e. C }
11	8, 10	nfeq 2236	. . . 4 |- F/ x { y | [ z / x ] y e. B } = { y | [ z / x ] y e. C }
12		sbab 2214	. . . . 5 |- ( x = z -> B = { y | [ z / x ] y e. B } )
13		sbab 2214	. . . . 5 |- ( x = z -> C = { y | [ z / x ] y e. C } )
14	12, 13	eqeq12d 2102	. . . 4 |- ( x = z -> ( B = C <-> { y | [ z / x ] y e. B } = { y | [ z / x ] y e. C } ) )
15	11, 14	sbie 1721	. . 3 |- ( [ z / x ] B = C <-> { y | [ z / x ] y e. B } = { y | [ z / x ] y e. C } )
16	1, 6, 15	vtoclbg 2680	. 2 |- ( A e. V -> ( [. A / x ]. B = C <-> { y | [. A / x ]. y e. B } = { y | [. A / x ]. y e. C } ) )
17		df-csb 2934	. . 3 |- [_ A / x ]_ B = { y | [. A / x ]. y e. B }
18		df-csb 2934	. . 3 |- [_ A / x ]_ C = { y | [. A / x ]. y e. C }
19	17, 18	eqeq12i 2101	. 2 |- ( [_ A / x ]_ B = [_ A / x ]_ C <-> { y | [. A / x ]. y e. B } = { y | [. A / x ]. y e. C } )
20	16, 19	syl6bbr 196	1 |- ( A e. V -> ( [. A / x ]. B = C <-> [_ A / x ]_ B = [_ A / x ]_ C ) )

Syntax hints:   -> wi 4   <-> wb 103   = wceq 1289   e. wcel 1438   [wsb 1692   {cab 2074   [.wsbc 2840   [_csb 2933

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-io 665  ax-5 1381  ax-7 1382  ax-gen 1383  ax-ie1 1427  ax-ie2 1428  ax-8 1440  ax-10 1441  ax-11 1442  ax-i12 1443  ax-bndl 1444  ax-4 1445  ax-17 1464  ax-i9 1468  ax-ial 1472  ax-i5r 1473  ax-ext 2070

This theorem depends on definitions:  df-bi 115  df-tru 1292  df-nf 1395  df-sb 1693  df-clab 2075  df-cleq 2081  df-clel 2084  df-nfc 2217  df-v 2621  df-sbc 2841  df-csb 2934

This theorem is referenced by:  sbcne12g  2949  sbceq1g  2951  sbceq2g  2953  sbcfng  5159