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Theorem pm2.21dd 99
Description: A contradiction implies anything. Deduction from pm2.21 100. (Contributed by Mario Carneiro, 9-Feb-2017.)
Hypotheses
Ref Expression
pm2.21dd.1  |-  ( ph  ->  ps )
pm2.21dd.2  |-  ( ph  ->  -.  ps )
Assertion
Ref Expression
pm2.21dd  |-  ( ph  ->  ch )

Proof of Theorem pm2.21dd
StepHypRef Expression
1 pm2.21dd.1 . 2  |-  ( ph  ->  ps )
2 pm2.21dd.2 . . 3  |-  ( ph  ->  -.  ps )
32pm2.21d 98 . 2  |-  ( ph  ->  ( ps  ->  ch ) )
41, 3mpd 14 1  |-  ( ph  ->  ch )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4
This theorem is referenced by:  pm2.21fal  1325  pm2.21ddne  2533  esumpcvgval  23461
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8
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