Theorem pm5.74rd 263

Description: Distribution of implication over biconditional (deduction rule). (Contributed by NM, 19-Mar-1997.)

Hypothesis

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

Assertion

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

Proof of Theorem pm5.74rd

Step	Hyp	Ref	Expression
1		pm5.74rd.1	. 2 |- ( ph -> ( ( ps -> ch ) <-> ( ps -> th ) ) )
2		pm5.74 259	. 2 |- ( ( ps -> ( ch <-> th ) ) <-> ( ( ps -> ch ) <-> ( ps -> th ) ) )
3	1, 2	sylibr 224	1 |- ( ph -> ( ps -> ( ch <-> th ) ) )

Syntax hints:   -> wi 4   <-> wb 196

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem depends on definitions:  df-bi 197

This theorem is referenced by:  pm5.35  942  wl-dral1d  33318