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Theorem pm5.12dc 854
Description: Excluded middle with antecedents for a decidable consequent. Based on theorem *5.12 of [WhiteheadRussell] p. 123. (Contributed by Jim Kingdon, 30-Mar-2018.)
Assertion
Ref Expression
pm5.12dc  |-  (DECID  ps  ->  ( ( ph  ->  ps )  \/  ( ph  ->  -.  ps ) ) )

Proof of Theorem pm5.12dc
StepHypRef Expression
1 df-dc 781 . 2  |-  (DECID  ps  <->  ( ps  \/  -.  ps ) )
2 ax-1 5 . . 3  |-  ( ps 
->  ( ph  ->  ps ) )
3 ax-1 5 . . 3  |-  ( -. 
ps  ->  ( ph  ->  -. 
ps ) )
42, 3orim12i 711 . 2  |-  ( ( ps  \/  -.  ps )  ->  ( ( ph  ->  ps )  \/  ( ph  ->  -.  ps )
) )
51, 4sylbi 119 1  |-  (DECID  ps  ->  ( ( ph  ->  ps )  \/  ( ph  ->  -.  ps ) ) )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    \/ wo 664  DECID wdc 780
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-io 665
This theorem depends on definitions:  df-bi 115  df-dc 781
This theorem is referenced by: (None)
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