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Theorem aibnbna 27850
Description: Given a implies b, not b, there exists a proof for not a. (Contributed by Jarvin Udandy, 1-Sep-2016.)
Hypotheses
Ref Expression
aibnbna.1  |-  ( ph  ->  ps )
aibnbna.2  |-  -.  ps
Assertion
Ref Expression
aibnbna  |-  -.  ph

Proof of Theorem aibnbna
StepHypRef Expression
1 aibnbna.2 . 2  |-  -.  ps
2 aibnbna.1 . 2  |-  ( ph  ->  ps )
31, 2mto 169 1  |-  -.  ph
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4
This theorem is referenced by:  aibnbaif  27851
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8
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