Theorem pm5.74ri 170

Description: Distribution of implication over biconditional (reverse inference rule). (Contributed by NM, 1-Aug-1994.)

Hypothesis

Ref	Expression
pm5.74ri.1	|- ( ( ph -> ps ) <-> ( ph -> ch ) )

Assertion

Ref	Expression
pm5.74ri	|- ( ph -> ( ps <-> ch ) )

Proof of Theorem pm5.74ri

Step	Hyp	Ref	Expression
1		pm5.74ri.1	. 2 |- ( ( ph -> ps ) <-> ( ph -> ch ) )
2		pm5.74 168	. 2 |- ( ( ph -> ( ps <-> ch ) ) <-> ( ( ph -> ps ) <-> ( ph -> ch ) ) )
3	1, 2	mpbir 134	1 |- ( ph -> ( ps <-> ch ) )

Syntax hints:   -> wi 4   <-> wb 98

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101

This theorem depends on definitions:  df-bi 110

This theorem is referenced by:  bitrd  177  bibi2d  221  tbt  236  cbval2  1796  sbco2d  1840  sbco2vd  1841