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Theorem 3orbi123d 1247
Description: Deduction joining 3 equivalences to form equivalence of disjunctions. (Contributed by NM, 20-Apr-1994.)
Hypotheses
Ref Expression
bi3d.1  |-  ( ph  ->  ( ps  <->  ch )
)
bi3d.2  |-  ( ph  ->  ( th  <->  ta )
)
bi3d.3  |-  ( ph  ->  ( et  <->  ze )
)
Assertion
Ref Expression
3orbi123d  |-  ( ph  ->  ( ( ps  \/  th  \/  et )  <->  ( ch  \/  ta  \/  ze )
) )

Proof of Theorem 3orbi123d
StepHypRef Expression
1 bi3d.1 . . . 4  |-  ( ph  ->  ( ps  <->  ch )
)
2 bi3d.2 . . . 4  |-  ( ph  ->  ( th  <->  ta )
)
31, 2orbi12d 742 . . 3  |-  ( ph  ->  ( ( ps  \/  th )  <->  ( ch  \/  ta ) ) )
4 bi3d.3 . . 3  |-  ( ph  ->  ( et  <->  ze )
)
53, 4orbi12d 742 . 2  |-  ( ph  ->  ( ( ( ps  \/  th )  \/  et )  <->  ( ( ch  \/  ta )  \/ 
ze ) ) )
6 df-3or 925 . 2  |-  ( ( ps  \/  th  \/  et )  <->  ( ( ps  \/  th )  \/  et ) )
7 df-3or 925 . 2  |-  ( ( ch  \/  ta  \/  ze )  <->  ( ( ch  \/  ta )  \/ 
ze ) )
85, 6, 73bitr4g 221 1  |-  ( ph  ->  ( ( ps  \/  th  \/  et )  <->  ( ch  \/  ta  \/  ze )
) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 103    \/ wo 664    \/ w3o 923
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-io 665
This theorem depends on definitions:  df-bi 115  df-3or 925
This theorem is referenced by:  ordtriexmid  4338  wetriext  4392  nntri3or  6254  tridc  6615  ltsopi  6879  pitri3or  6881  nqtri3or  6955  elz  8752  ztri3or  8793  qtri3or  9654
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