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Theorem nsyli 623
Description: A negated syllogism inference. (Contributed by NM, 3-May-1994.)
Hypotheses
Ref Expression
nsyli.1  |-  ( ph  ->  ( ps  ->  ch ) )
nsyli.2  |-  ( th 
->  -.  ch )
Assertion
Ref Expression
nsyli  |-  ( ph  ->  ( th  ->  -.  ps ) )

Proof of Theorem nsyli
StepHypRef Expression
1 nsyli.2 . 2  |-  ( th 
->  -.  ch )
2 nsyli.1 . . 3  |-  ( ph  ->  ( ps  ->  ch ) )
32con3d 605 . 2  |-  ( ph  ->  ( -.  ch  ->  -. 
ps ) )
41, 3syl5 32 1  |-  ( ph  ->  ( th  ->  -.  ps ) )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-in1 588  ax-in2 589
This theorem is referenced by: (None)
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