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Theorem 3orit 25204
Description: Closed form of 3ori 1245, (Contributed by Scott Fenton, 20-Apr-2011.)
Assertion
Ref Expression
3orit  |-  ( (
ph  \/  ps  \/  ch )  <->  ( ( -. 
ph  /\  -.  ps )  ->  ch ) )

Proof of Theorem 3orit
StepHypRef Expression
1 df-3or 938 . 2  |-  ( (
ph  \/  ps  \/  ch )  <->  ( ( ph  \/  ps )  \/  ch ) )
2 df-or 361 . 2  |-  ( ( ( ph  \/  ps )  \/  ch )  <->  ( -.  ( ph  \/  ps )  ->  ch )
)
3 ioran 478 . . 3  |-  ( -.  ( ph  \/  ps ) 
<->  ( -.  ph  /\  -.  ps ) )
43imbi1i 317 . 2  |-  ( ( -.  ( ph  \/  ps )  ->  ch )  <->  ( ( -.  ph  /\  -.  ps )  ->  ch ) )
51, 2, 43bitri 264 1  |-  ( (
ph  \/  ps  \/  ch )  <->  ( ( -. 
ph  /\  -.  ps )  ->  ch ) )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    <-> wb 178    \/ wo 359    /\ wa 360    \/ w3o 936
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 179  df-or 361  df-an 362  df-3or 938
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