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Theorem impi 148
Description: An importation inference. (Contributed by NM, 29-Dec-1992.) (Proof shortened by Wolf Lammen, 20-Jul-2013.)
Hypothesis
Ref Expression
impi.1  |-  ( ph  ->  ( ps  ->  ch ) )
Assertion
Ref Expression
impi  |-  ( -.  ( ph  ->  -.  ps )  ->  ch )

Proof of Theorem impi
StepHypRef Expression
1 impi.1 . . 3  |-  ( ph  ->  ( ps  ->  ch ) )
21con3rr3 136 . 2  |-  ( -. 
ch  ->  ( ph  ->  -. 
ps ) )
32con1i 129 1  |-  ( -.  ( ph  ->  -.  ps )  ->  ch )
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    -> wi 4
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem is referenced by:  simprim  150  dfbi1  192  imp  427
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