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Theorem elimhyp2v 3614
Description: Eliminate a hypothesis containing 2 class variables. (Contributed by NM, 14-Aug-1999.)
Hypotheses
Ref Expression
elimhyp2v.1  |-  ( A  =  if ( ph ,  A ,  C )  ->  ( ph  <->  ch )
)
elimhyp2v.2  |-  ( B  =  if ( ph ,  B ,  D )  ->  ( ch  <->  th )
)
elimhyp2v.3  |-  ( C  =  if ( ph ,  A ,  C )  ->  ( ta  <->  et )
)
elimhyp2v.4  |-  ( D  =  if ( ph ,  B ,  D )  ->  ( et  <->  th )
)
elimhyp2v.5  |-  ta
Assertion
Ref Expression
elimhyp2v  |-  th

Proof of Theorem elimhyp2v
StepHypRef Expression
1 iftrue 3571 . . . . . 6  |-  ( ph  ->  if ( ph ,  A ,  C )  =  A )
21eqcomd 2288 . . . . 5  |-  ( ph  ->  A  =  if (
ph ,  A ,  C ) )
3 elimhyp2v.1 . . . . 5  |-  ( A  =  if ( ph ,  A ,  C )  ->  ( ph  <->  ch )
)
42, 3syl 15 . . . 4  |-  ( ph  ->  ( ph  <->  ch )
)
5 iftrue 3571 . . . . . 6  |-  ( ph  ->  if ( ph ,  B ,  D )  =  B )
65eqcomd 2288 . . . . 5  |-  ( ph  ->  B  =  if (
ph ,  B ,  D ) )
7 elimhyp2v.2 . . . . 5  |-  ( B  =  if ( ph ,  B ,  D )  ->  ( ch  <->  th )
)
86, 7syl 15 . . . 4  |-  ( ph  ->  ( ch  <->  th )
)
94, 8bitrd 244 . . 3  |-  ( ph  ->  ( ph  <->  th )
)
109ibi 232 . 2  |-  ( ph  ->  th )
11 elimhyp2v.5 . . 3  |-  ta
12 iffalse 3572 . . . . . 6  |-  ( -. 
ph  ->  if ( ph ,  A ,  C )  =  C )
1312eqcomd 2288 . . . . 5  |-  ( -. 
ph  ->  C  =  if ( ph ,  A ,  C ) )
14 elimhyp2v.3 . . . . 5  |-  ( C  =  if ( ph ,  A ,  C )  ->  ( ta  <->  et )
)
1513, 14syl 15 . . . 4  |-  ( -. 
ph  ->  ( ta  <->  et )
)
16 iffalse 3572 . . . . . 6  |-  ( -. 
ph  ->  if ( ph ,  B ,  D )  =  D )
1716eqcomd 2288 . . . . 5  |-  ( -. 
ph  ->  D  =  if ( ph ,  B ,  D ) )
18 elimhyp2v.4 . . . . 5  |-  ( D  =  if ( ph ,  B ,  D )  ->  ( et  <->  th )
)
1917, 18syl 15 . . . 4  |-  ( -. 
ph  ->  ( et  <->  th )
)
2015, 19bitrd 244 . . 3  |-  ( -. 
ph  ->  ( ta  <->  th )
)
2111, 20mpbii 202 . 2  |-  ( -. 
ph  ->  th )
2210, 21pm2.61i 156 1  |-  th
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    <-> wb 176    = wceq 1623   ifcif 3565
This theorem is referenced by:  omlsi  21983
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1533  ax-5 1544  ax-17 1603  ax-9 1635  ax-8 1643  ax-6 1703  ax-7 1708  ax-11 1715  ax-12 1866  ax-ext 2264
This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-tru 1310  df-ex 1529  df-nf 1532  df-sb 1630  df-clab 2270  df-cleq 2276  df-clel 2279  df-if 3566
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