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Theorem dedth4h 3622
Description: Weak deduction theorem eliminating four hypotheses. See comments in dedth2h 3620. (Contributed by NM, 16-May-1999.)
Hypotheses
Ref Expression
dedth4h.1  |-  ( A  =  if ( ph ,  A ,  R )  ->  ( ta  <->  et )
)
dedth4h.2  |-  ( B  =  if ( ps ,  B ,  S
)  ->  ( et  <->  ze ) )
dedth4h.3  |-  ( C  =  if ( ch ,  C ,  F
)  ->  ( ze  <->  si ) )
dedth4h.4  |-  ( D  =  if ( th ,  D ,  G
)  ->  ( si  <->  rh ) )
dedth4h.5  |-  rh
Assertion
Ref Expression
dedth4h  |-  ( ( ( ph  /\  ps )  /\  ( ch  /\  th ) )  ->  ta )

Proof of Theorem dedth4h
StepHypRef Expression
1 dedth4h.1 . . . 4  |-  ( A  =  if ( ph ,  A ,  R )  ->  ( ta  <->  et )
)
21imbi2d 307 . . 3  |-  ( A  =  if ( ph ,  A ,  R )  ->  ( ( ( ch  /\  th )  ->  ta )  <->  ( ( ch  /\  th )  ->  et ) ) )
3 dedth4h.2 . . . 4  |-  ( B  =  if ( ps ,  B ,  S
)  ->  ( et  <->  ze ) )
43imbi2d 307 . . 3  |-  ( B  =  if ( ps ,  B ,  S
)  ->  ( (
( ch  /\  th )  ->  et )  <->  ( ( ch  /\  th )  ->  ze ) ) )
5 dedth4h.3 . . . 4  |-  ( C  =  if ( ch ,  C ,  F
)  ->  ( ze  <->  si ) )
6 dedth4h.4 . . . 4  |-  ( D  =  if ( th ,  D ,  G
)  ->  ( si  <->  rh ) )
7 dedth4h.5 . . . 4  |-  rh
85, 6, 7dedth2h 3620 . . 3  |-  ( ( ch  /\  th )  ->  ze )
92, 4, 8dedth2h 3620 . 2  |-  ( (
ph  /\  ps )  ->  ( ( ch  /\  th )  ->  ta )
)
109imp 418 1  |-  ( ( ( ph  /\  ps )  /\  ( ch  /\  th ) )  ->  ta )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 176    /\ wa 358    = wceq 1632   ifcif 3578
This theorem is referenced by:  dedth4v  3625  omopth  6672  nn0opth2  11303  hvsubsub4  21655  norm3lemt  21747  eigorth  22434  ax5seglem8  24636  fprg  25236
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1536  ax-5 1547  ax-17 1606  ax-9 1644  ax-8 1661  ax-6 1715  ax-7 1720  ax-11 1727  ax-12 1878  ax-ext 2277
This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-tru 1310  df-ex 1532  df-nf 1535  df-sb 1639  df-clab 2283  df-cleq 2289  df-clel 2292  df-if 3579
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