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Theorem pm5.74ri 179
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
StepHypRef Expression
1 pm5.74ri.1 . 2  |-  ( (
ph  ->  ps )  <->  ( ph  ->  ch ) )
2 pm5.74 177 . 2  |-  ( (
ph  ->  ( ps  <->  ch )
)  <->  ( ( ph  ->  ps )  <->  ( ph  ->  ch ) ) )
31, 2mpbir 144 1  |-  ( ph  ->  ( ps  <->  ch )
)
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 103
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106
This theorem depends on definitions:  df-bi 115
This theorem is referenced by:  bitrd  186  bibi2d  230  tbt  245  cbval2  1838  sbco2d  1882  sbco2vd  1883  isprm2  10643
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