Theorem elsb2 2156

Description: Substitution for the second argument of the non-logical predicate in an atomic formula. See elsb1 2155 for substitution for the first argument. (Contributed by Rodolfo Medina, 3-Apr-2010.) (Proof shortened by Andrew Salmon, 14-Jun-2011.)

Assertion

Ref	Expression
elsb2	|- ( [ y / x ] z e. x <-> z e. y )

Distinct variable group:   x, z

Proof of Theorem elsb2

Dummy variable w is distinct from all other variables.

Step	Hyp	Ref	Expression
1		ax-17 1526	. . . . 5 |- ( z e. x -> A. w z e. x )
2		elequ2 2153	. . . . 5 |- ( w = x -> ( z e. w <-> z e. x ) )
3	1, 2	sbieh 1790	. . . 4 |- ( [ x / w ] z e. w <-> z e. x )
4	3	sbbii 1765	. . 3 |- ( [ y / x ] [ x / w ] z e. w <-> [ y / x ] z e. x )
5		ax-17 1526	. . . 4 |- ( z e. w -> A. x z e. w )
6	5	sbco2h 1964	. . 3 |- ( [ y / x ] [ x / w ] z e. w <-> [ y / w ] z e. w )
7	4, 6	bitr3i 186	. 2 |- ( [ y / x ] z e. x <-> [ y / w ] z e. w )
8		equsb1 1785	. . . 4 |- [ y / w ] w = y
9		elequ2 2153	. . . . 5 |- ( w = y -> ( z e. w <-> z e. y ) )
10	9	sbimi 1764	. . . 4 |- ( [ y / w ] w = y -> [ y / w ] ( z e. w <-> z e. y ) )
11	8, 10	ax-mp 5	. . 3 |- [ y / w ] ( z e. w <-> z e. y )
12		sbbi 1959	. . 3 |- ( [ y / w ] ( z e. w <-> z e. y ) <-> ( [ y / w ] z e. w <-> [ y / w ] z e. y ) )
13	11, 12	mpbi 145	. 2 |- ( [ y / w ] z e. w <-> [ y / w ] z e. y )
14		ax-17 1526	. . 3 |- ( z e. y -> A. w z e. y )
15	14	sbh 1776	. 2 |- ( [ y / w ] z e. y <-> z e. y )
16	7, 13, 15	3bitri 206	1 |- ( [ y / x ] z e. x <-> z e. y )

Syntax hints:   <-> wb 105   [wsb 1762

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 709  ax-5 1447  ax-7 1448  ax-gen 1449  ax-ie1 1493  ax-ie2 1494  ax-8 1504  ax-10 1505  ax-11 1506  ax-i12 1507  ax-bndl 1509  ax-4 1510  ax-17 1526  ax-i9 1530  ax-ial 1534  ax-i5r 1535  ax-14 2151

This theorem depends on definitions:  df-bi 117  df-nf 1461  df-sb 1763

This theorem is referenced by: (None)