Theorem sbrbif 1962

Description: Introduce right biconditional inside of a substitution. (Contributed by NM, 18-Aug-1993.)

Hypotheses

Ref	Expression
sbrbif.1	|- ( ch -> A. x ch )
sbrbif.2	|- ( [ y / x ] ph <-> ps )

Assertion

Ref	Expression
sbrbif	|- ( [ y / x ] ( ph <-> ch ) <-> ( ps <-> ch ) )

Proof of Theorem sbrbif

Step	Hyp	Ref	Expression
1		sbrbif.2	. . 3 |- ( [ y / x ] ph <-> ps )
2	1	sbrbis 1961	. 2 |- ( [ y / x ] ( ph <-> ch ) <-> ( ps <-> [ y / x ] ch ) )
3		sbrbif.1	. . . 4 |- ( ch -> A. x ch )
4	3	sbh 1776	. . 3 |- ( [ y / x ] ch <-> ch )
5	4	bibi2i 227	. 2 |- ( ( ps <-> [ y / x ] ch ) <-> ( ps <-> ch ) )
6	2, 5	bitri 184	1 |- ( [ y / x ] ( ph <-> ch ) <-> ( ps <-> ch ) )

Syntax hints:   -> wi 4   <-> wb 105   A.wal 1351   [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-4 1510  ax-17 1526  ax-i9 1530  ax-ial 1534  ax-i5r 1535

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

This theorem is referenced by: (None)