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Theorem pm2.61nii 158
Description: Inference eliminating two antecedents. (Contributed by NM, 5-Aug-1993.) (Proof shortened by Andrew Salmon, 25-May-2011.) (Proof shortened by Wolf Lammen, 13-Nov-2012.)
Hypotheses
Ref Expression
pm2.61nii.1  |-  ( ph  ->  ( ps  ->  ch ) )
pm2.61nii.2  |-  ( -. 
ph  ->  ch )
pm2.61nii.3  |-  ( -. 
ps  ->  ch )
Assertion
Ref Expression
pm2.61nii  |-  ch

Proof of Theorem pm2.61nii
StepHypRef Expression
1 pm2.61nii.1 . . 3  |-  ( ph  ->  ( ps  ->  ch ) )
2 pm2.61nii.3 . . 3  |-  ( -. 
ps  ->  ch )
31, 2pm2.61d1 151 . 2  |-  ( ph  ->  ch )
4 pm2.61nii.2 . 2  |-  ( -. 
ph  ->  ch )
53, 4pm2.61i 156 1  |-  ch
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4
This theorem is referenced by:  ecase  908  3ecase  1286  prex  4233
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8
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