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Theorem condan 792
Description: Proof by contradiction. (Contributed by NM, 9-Feb-2006.) (Proof shortened by Wolf Lammen, 19-Jun-2014.)
Hypotheses
Ref Expression
condan.1  |-  ( (
ph  /\  -.  ps )  ->  ch )
condan.2  |-  ( (
ph  /\  -.  ps )  ->  -.  ch )
Assertion
Ref Expression
condan  |-  ( ph  ->  ps )

Proof of Theorem condan
StepHypRef Expression
1 condan.1 . . 3  |-  ( (
ph  /\  -.  ps )  ->  ch )
2 condan.2 . . 3  |-  ( (
ph  /\  -.  ps )  ->  -.  ch )
31, 2pm2.65da 576 . 2  |-  ( ph  ->  -.  -.  ps )
43notnotrd 113 1  |-  ( ph  ->  ps )
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    -> wi 4    /\ wa 369
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 185  df-an 371
This theorem is referenced by:  rlimcld2  13160  perfectlem2  22687  coltr  23176  coltr2  23177  submomnd  26309  suborng  26419  ballotlemfc0  27011  ballotlemic  27025  stoweidlem52  29987
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