Theorem clelsb4 2263

Description: Substitution applied to an atomic wff (class version of elsb4 2136). (Contributed by Jim Kingdon, 22-Nov-2018.)

Assertion

Ref	Expression
clelsb4	|- ( [ y / x ] A e. x <-> A e. y )

Distinct variable group:   x, A

Allowed substitution hint:   A( y)

Proof of Theorem clelsb4

Dummy variable w is distinct from all other variables.

Step	Hyp	Ref	Expression
1		nfv 1508	. . 3 |- F/ x A e. w
2	1	sbco2 1945	. 2 |- ( [ y / x ] [ x / w ] A e. w <-> [ y / w ] A e. w )
3		nfv 1508	. . . 4 |- F/ w A e. x
4		eleq2 2221	. . . 4 |- ( w = x -> ( A e. w <-> A e. x ) )
5	3, 4	sbie 1771	. . 3 |- ( [ x / w ] A e. w <-> A e. x )
6	5	sbbii 1745	. 2 |- ( [ y / x ] [ x / w ] A e. w <-> [ y / x ] A e. x )
7		nfv 1508	. . 3 |- F/ w A e. y
8		eleq2 2221	. . 3 |- ( w = y -> ( A e. w <-> A e. y ) )
9	7, 8	sbie 1771	. 2 |- ( [ y / w ] A e. w <-> A e. y )
10	2, 6, 9	3bitr3i 209	1 |- ( [ y / x ] A e. x <-> A e. y )

Syntax hints:   <-> wb 104   [wsb 1742   e. wcel 2128

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-nf 1441  df-sb 1743  df-cleq 2150  df-clel 2153

This theorem is referenced by:  peano1  4551  peano2  4552