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Theorem elimdhyp 3792
Description: Version of elimhyp 3787 where the hypothesis is deduced from the final antecedent. See ghomgrplem 25100 for an example of its use. (Contributed by Paul Chapman, 25-Mar-2008.)
Hypotheses
Ref Expression
elimdhyp.1  |-  ( ph  ->  ps )
elimdhyp.2  |-  ( A  =  if ( ph ,  A ,  B )  ->  ( ps  <->  ch )
)
elimdhyp.3  |-  ( B  =  if ( ph ,  A ,  B )  ->  ( th  <->  ch )
)
elimdhyp.4  |-  th
Assertion
Ref Expression
elimdhyp  |-  ch

Proof of Theorem elimdhyp
StepHypRef Expression
1 elimdhyp.1 . . 3  |-  ( ph  ->  ps )
2 iftrue 3745 . . . . 5  |-  ( ph  ->  if ( ph ,  A ,  B )  =  A )
32eqcomd 2441 . . . 4  |-  ( ph  ->  A  =  if (
ph ,  A ,  B ) )
4 elimdhyp.2 . . . 4  |-  ( A  =  if ( ph ,  A ,  B )  ->  ( ps  <->  ch )
)
53, 4syl 16 . . 3  |-  ( ph  ->  ( ps  <->  ch )
)
61, 5mpbid 202 . 2  |-  ( ph  ->  ch )
7 elimdhyp.4 . . 3  |-  th
8 iffalse 3746 . . . . 5  |-  ( -. 
ph  ->  if ( ph ,  A ,  B )  =  B )
98eqcomd 2441 . . . 4  |-  ( -. 
ph  ->  B  =  if ( ph ,  A ,  B ) )
10 elimdhyp.3 . . . 4  |-  ( B  =  if ( ph ,  A ,  B )  ->  ( th  <->  ch )
)
119, 10syl 16 . . 3  |-  ( -. 
ph  ->  ( th  <->  ch )
)
127, 11mpbii 203 . 2  |-  ( -. 
ph  ->  ch )
136, 12pm2.61i 158 1  |-  ch
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    <-> wb 177    = wceq 1652   ifcif 3739
This theorem is referenced by:  divalg  12923  ghomgrplem  25100
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1555  ax-5 1566  ax-17 1626  ax-9 1666  ax-8 1687  ax-6 1744  ax-7 1749  ax-11 1761  ax-12 1950  ax-ext 2417
This theorem depends on definitions:  df-bi 178  df-or 360  df-an 361  df-tru 1328  df-ex 1551  df-nf 1554  df-sb 1659  df-clab 2423  df-cleq 2429  df-clel 2432  df-if 3740
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