ILE Home Intuitionistic Logic Explorer < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  ILE Home  >  Th. List  >  pm3.12dc Unicode version

Theorem pm3.12dc 865
Description: Theorem *3.12 of [WhiteheadRussell] p. 111, but for decidable propositions. (Contributed by Jim Kingdon, 22-Apr-2018.)
Assertion
Ref Expression
pm3.12dc  |-  (DECID  ph  ->  (DECID  ps 
->  ( ( -.  ph  \/  -.  ps )  \/  ( ph  /\  ps ) ) ) )

Proof of Theorem pm3.12dc
StepHypRef Expression
1 pm3.11dc 864 . . . 4  |-  (DECID  ph  ->  (DECID  ps 
->  ( -.  ( -. 
ph  \/  -.  ps )  ->  ( ph  /\  ps ) ) ) )
21imp 115 . . 3  |-  ( (DECID  ph  /\ DECID  ps )  ->  ( -.  ( -.  ph  \/  -.  ps )  ->  ( ph  /\  ps ) ) )
3 dcn 746 . . . . . 6  |-  (DECID  ph  -> DECID  -.  ph )
4 dcn 746 . . . . . 6  |-  (DECID  ps  -> DECID  -.  ps )
5 dcor 843 . . . . . 6  |-  (DECID  -.  ph  ->  (DECID  -.  ps  -> DECID  ( -.  ph  \/  -.  ps ) ) )
63, 4, 5syl2im 34 . . . . 5  |-  (DECID  ph  ->  (DECID  ps 
-> DECID  ( -.  ph  \/  -.  ps ) ) )
7 dfordc 791 . . . . 5  |-  (DECID  ( -. 
ph  \/  -.  ps )  ->  ( ( ( -. 
ph  \/  -.  ps )  \/  ( ph  /\  ps ) )  <->  ( -.  ( -.  ph  \/  -.  ps )  ->  ( ph  /\ 
ps ) ) ) )
86, 7syl6 29 . . . 4  |-  (DECID  ph  ->  (DECID  ps 
->  ( ( ( -. 
ph  \/  -.  ps )  \/  ( ph  /\  ps ) )  <->  ( -.  ( -.  ph  \/  -.  ps )  ->  ( ph  /\ 
ps ) ) ) ) )
98imp 115 . . 3  |-  ( (DECID  ph  /\ DECID  ps )  ->  ( ( ( -.  ph  \/  -.  ps )  \/  ( ph  /\  ps ) )  <-> 
( -.  ( -. 
ph  \/  -.  ps )  ->  ( ph  /\  ps ) ) ) )
102, 9mpbird 156 . 2  |-  ( (DECID  ph  /\ DECID  ps )  ->  ( ( -. 
ph  \/  -.  ps )  \/  ( ph  /\  ps ) ) )
1110ex 108 1  |-  (DECID  ph  ->  (DECID  ps 
->  ( ( -.  ph  \/  -.  ps )  \/  ( ph  /\  ps ) ) ) )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    /\ wa 97    <-> wb 98    \/ wo 629  DECID wdc 742
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-in1 544  ax-in2 545  ax-io 630
This theorem depends on definitions:  df-bi 110  df-dc 743
This theorem is referenced by: (None)
  Copyright terms: Public domain W3C validator