The Mizar article:

Calculus of Propositions

by
Jan Popiolek, and
Andrzej Trybulec

Received October 23, 1990

Copyright (c) 1990 Association of Mizar Users

MML identifier: PROCAL_1
[ MML identifier index ]


environ

 vocabulary CQC_LANG, ZF_LANG, CQC_THE1;
 notation SUBSET_1, CQC_LANG, CQC_THE1;
 constructors CQC_THE1, XBOOLE_0;
 clusters CQC_LANG, ZFMISC_1, XBOOLE_0;
 theorems CQC_THE1, QC_LANG2, LUKASI_1;

begin
 reserve p, q, r, s for Element of CQC-WFF;

             :::::::::::::::::::::::::::::
             ::   T A U T O L O G I E   ::
             :::::::::::::::::::::::::::::

theorem Th1:
  'not' ( p '&' 'not' p ) in TAUT
proof
    p => p in TAUT by LUKASI_1:4;
  hence thesis by QC_LANG2:def 2;
end;

Lm1:  p 'or' q = ( 'not' p => q )
proof
    'not' p => q = 'not' ( 'not' p '&' 'not' q ) by QC_LANG2:def 2;
  hence thesis by QC_LANG2:def 3;
end;

theorem Th2:
  p 'or' 'not' p in TAUT
proof
    'not' p => 'not' p in TAUT by LUKASI_1:4;
  hence thesis by Lm1;
end;

theorem Th3:
  p => ( p 'or' q ) in TAUT
proof
    p => ( 'not' p => q ) in TAUT by CQC_THE1:79;
  hence thesis by Lm1;
end;

theorem Th4:
  q => ( p 'or' q ) in TAUT
proof
    q => ( 'not' p => q ) in TAUT by LUKASI_1:5;
  hence thesis by Lm1;
end;

theorem Th5:
  ( p 'or' q ) => ( 'not' p => q ) in TAUT
proof
    ( 'not' p => q ) => ( 'not' p => q ) in TAUT by LUKASI_1:4;
  hence thesis by Lm1;
end;

theorem Th6:
  'not' ( p 'or' q ) => ( 'not' p '&' 'not' q ) in TAUT
proof
    'not' ( p 'or' q ) = 'not' 'not' ( 'not' p '&' 'not' q ) by QC_LANG2:def 3;
  hence thesis by LUKASI_1:25;
end;

theorem Th7:
  ( 'not' p '&' 'not' q ) => 'not' ( p 'or' q ) in TAUT
proof
    'not' ( p 'or' q ) = 'not' 'not' ( 'not' p '&' 'not' q ) by QC_LANG2:def 3;
  hence thesis by LUKASI_1:27;
end;

theorem Th8:
  ( p 'or' q ) => ( q 'or' p ) in TAUT
proof
    ( 'not' p => q ) => ( 'not' q => p ) in TAUT by LUKASI_1:31;
  then ( p 'or' q ) => ( 'not' q => p ) in TAUT by Lm1;
  hence thesis by Lm1;
end;

theorem
    'not' p 'or' p in TAUT
proof
A1: ( p 'or' 'not' p ) => ( 'not' p 'or' p ) in TAUT by Th8;
     p 'or' 'not' p in TAUT by Th2;
   hence thesis by A1,CQC_THE1:82;
end;

theorem
    'not' ( p 'or' q ) => 'not' p in TAUT
proof
A1: ( p => ( p 'or' q )) => ( 'not' ( p 'or' q ) => 'not'
 p ) in TAUT by LUKASI_1:26;
     ( p => ( p 'or' q )) in TAUT by Th3;
   hence thesis by A1,CQC_THE1:82;
end;

theorem Th11:
  ( p 'or' p ) => p in TAUT
proof
A1: ( p 'or' p ) => ( 'not' p => p ) in TAUT by Th5;
     ( 'not' p => p ) => p in TAUT by CQC_THE1:78;
   hence thesis by A1,LUKASI_1:3;
end;

theorem
    p => ( p 'or' p ) in TAUT by Th3;

theorem
    ( p '&' 'not' p ) => q in TAUT
proof
    'not' ( p '&' 'not' p ) in TAUT by Th1;
  then 'not' q => 'not' ( p '&' 'not' p ) in TAUT by LUKASI_1:13;
  hence thesis by LUKASI_1:35;
end;

theorem
    ( p => q ) => ( 'not' p 'or' q ) in TAUT
proof
A1: ( 'not' 'not' p => q ) = ( 'not' p 'or' q ) by Lm1;
A2: 'not' 'not' p => p in TAUT by LUKASI_1:25;
     ( 'not' 'not' p => p ) => (( p => q ) => ( 'not' 'not'
 p => q )) in TAUT by LUKASI_1:1;
   hence thesis by A1,A2,CQC_THE1:82;
end;

Lm2: ( p '&' q ) => ( 'not' 'not' p '&' q ) in TAUT
proof
A1: ( p => 'not' 'not' p ) => ('not' ( 'not' 'not' p '&' q ) => 'not'
 ( p '&' q )) in TAUT
                        by CQC_THE1:80;
     p => 'not' 'not' p in TAUT by LUKASI_1:27;
   then 'not' ( 'not' 'not' p '&' q ) => 'not'
 ( p '&' q ) in TAUT by A1,CQC_THE1:82;
   hence thesis by LUKASI_1:35;
   end;

Lm3: ( 'not' 'not' p '&' q ) => ( p '&' q ) in TAUT
proof
A1: ( 'not' 'not' p => p ) => ('not' ( p '&' q ) => 'not' ( 'not' 'not'
 p '&' q )) in TAUT by CQC_THE1:80;
     'not' 'not' p => p in TAUT by LUKASI_1:25;
   then 'not' ( p '&' q ) => 'not' ( 'not' 'not'
 p '&' q ) in TAUT by A1,CQC_THE1:82;
   hence thesis by LUKASI_1:35;
   end;

theorem Th15:
  ( p '&' q ) => 'not' ( p => 'not' q ) in TAUT
   proof
A1:  q '&' p => 'not' 'not' q '&' p in TAUT by Lm2;
       p '&' q => q '&' p in TAUT by CQC_THE1:81;
then A2:  p '&' q => 'not' 'not' q '&' p in TAUT by A1,LUKASI_1:3;
       'not' 'not' q '&' p => p '&' 'not' 'not' q in TAUT by CQC_THE1:81;
then A3:   ( p '&' q ) => ( p '&' 'not' 'not' q ) in TAUT by A2,LUKASI_1:3;
       ( p '&' 'not' 'not' q ) => 'not' 'not' ( p '&' 'not' 'not'
 q ) in TAUT by LUKASI_1:27;
     then ( p '&' q ) => 'not' 'not' ( p '&' 'not' 'not'
 q ) in TAUT by A3,LUKASI_1:3;
    hence thesis by QC_LANG2:def 2;
   end;

theorem Th16:
  'not' ( p => 'not' q ) => ( p '&' q ) in TAUT
   proof
A1:  p '&' 'not' 'not' q => 'not' 'not' q '&' p in TAUT by CQC_THE1:81;
       'not' 'not' q '&' p => q '&' p in TAUT by Lm3;
then A2:  p '&' 'not' 'not' q => q '&' p in TAUT by A1,LUKASI_1:3;
       q '&' p => p '&' q in TAUT by CQC_THE1:81;
then A3:   ( p '&' 'not' 'not' q ) => ( p '&' q ) in TAUT by A2,LUKASI_1:3;
       'not' 'not' ( p '&' 'not' 'not' q ) => ( p '&' 'not' 'not'
 q ) in TAUT by LUKASI_1:25;
     then 'not' 'not' ( p '&' 'not' 'not'
 q ) => ( p '&' q ) in TAUT by A3,LUKASI_1:3;
    hence thesis by QC_LANG2:def 2;
   end;

theorem Th17:
  'not' ( p '&' q ) => ( 'not' p 'or' 'not' q ) in TAUT
proof
     'not' ( p => 'not' q ) => p '&' q in TAUT by Th16;
then A1: 'not' ( p '&' q ) => 'not' 'not' ( p => 'not' q ) in TAUT by LUKASI_1:
34;
     'not' 'not' ( p => 'not' q ) => ( p => 'not'
 q ) in TAUT by LUKASI_1:25;
then A2: 'not' ( p '&' q ) => ( p => 'not' q ) in TAUT by A1,LUKASI_1:3;
A3: 'not' 'not' p => p in TAUT by LUKASI_1:25;
     ( 'not' 'not' p => p ) => (( p => 'not' q ) => ( 'not' 'not' p => 'not'
 q )) in TAUT
   by LUKASI_1:1;
   then ( p => 'not' q ) => ( 'not' 'not' p => 'not'
 q ) in TAUT by A3,CQC_THE1:82;
   then 'not' ( p '&' q ) => ( 'not' 'not' p => 'not'
 q ) in TAUT by A2,LUKASI_1:3;
   hence thesis by Lm1;
end;

theorem Th18:
  ( 'not' p 'or' 'not' q ) => 'not' ( p '&' q ) in TAUT
proof
A1: ( 'not' p 'or' 'not' q ) = ( 'not' 'not' p => 'not' q ) by Lm1;
A2: p => 'not' 'not' p in TAUT by LUKASI_1:27;
     ( p => 'not' 'not' p ) => (( 'not' 'not' p => 'not' q ) => ( p => 'not'
 q )) in TAUT
        by LUKASI_1:1;
then A3: ( 'not' p 'or' 'not' q ) => ( p => 'not' q ) in TAUT by A1,A2,CQC_THE1
:82;
     p '&' q => 'not' ( p => 'not' q ) in TAUT by Th15;
then A4: 'not' 'not' ( p => 'not' q ) => 'not' ( p '&' q ) in TAUT by LUKASI_1:
34;
     ( p => 'not' q ) => 'not' 'not' ( p => 'not'
 q ) in TAUT by LUKASI_1:27;
   then ( p => 'not' q ) => 'not' ( p '&' q ) in TAUT by A4,LUKASI_1:3;
   hence thesis by A3,LUKASI_1:3;
end;

theorem Th19:
  ( p '&' q ) => p in TAUT
proof
     'not' p => ( 'not' p 'or' 'not' q ) in TAUT by Th3;
then A1: 'not' ( 'not' p 'or' 'not' q ) => 'not' 'not' p in TAUT by LUKASI_1:34
;
     'not' 'not' p => p in TAUT by LUKASI_1:25;
then A2: 'not' ( 'not' p 'or' 'not' q ) => p in TAUT by A1,LUKASI_1:3;
     ( 'not' p 'or' 'not' q ) => 'not' ( p '&' q ) in TAUT by Th18;
then A3: 'not' 'not' ( p '&' q ) => 'not' ( 'not' p 'or' 'not'
 q ) in TAUT by LUKASI_1:34;
     ( p '&' q ) => 'not' 'not' ( p '&' q ) in TAUT by LUKASI_1:27;
   then ( p '&' q ) => 'not' ( 'not' p 'or' 'not' q ) in TAUT by A3,LUKASI_1:3
;
   hence thesis by A2,LUKASI_1:3;
end;

theorem Th20:
  ( p '&' q ) => ( p 'or' q ) in TAUT
proof
A1:  p => ( p 'or' q ) in TAUT by Th3;
      ( p '&' q ) => p in TAUT by Th19;
    hence thesis by A1,LUKASI_1:3;
end;

theorem Th21:
  ( p '&' q ) => q in TAUT
proof
A1: ( q '&' p ) => q in TAUT by Th19;
     ( p '&' q ) => ( q '&' p ) in TAUT by CQC_THE1:81;
   hence thesis by A1,LUKASI_1:3;
end;

theorem
    p => p '&' p in TAUT
proof
A1: 'not' ( p '&' p ) => ( 'not' p 'or' 'not' p ) in TAUT by Th17;
     ( 'not' p 'or' 'not' p ) => 'not' p in TAUT by Th11;
   then 'not' ( p '&' p ) => 'not' p in TAUT by A1,LUKASI_1:3;
   hence thesis by LUKASI_1:35;
end;

theorem
    ( p <=> q ) => ( p => q ) in TAUT
proof
    ( p <=> q ) = ( p => q ) '&' ( q => p ) by QC_LANG2:def 4;
  hence thesis by Th19;
end;

theorem
    ( p <=> q ) => ( q => p ) in TAUT
proof
    ( p <=> q ) = ( p => q ) '&' ( q => p ) by QC_LANG2:def 4;
  hence thesis by Th21;
end;

theorem Th25:
  (( p 'or' q ) 'or' r ) => ( p 'or' ( q 'or' r )) in TAUT
proof
A1: (( p 'or' q ) 'or' r ) => ( r 'or' ( p 'or' q )) in TAUT by Th8;
     ( r 'or' ( p 'or' q )) => ( 'not' r => ( p 'or' q )) in TAUT by Th5;
   then (( p 'or' q ) 'or' r ) => ( 'not' r => ( p 'or' q )) in TAUT
       by A1,LUKASI_1:3;
then A2: (( p 'or' q ) 'or' r ) => ( 'not' r => ( 'not' p => q )) in TAUT by
Lm1;
     ( 'not' r => ( 'not' p => q )) => ( 'not' p => ( 'not' r => q )) in TAUT
       by LUKASI_1:8;
then A3: (( p 'or' q ) 'or' r ) => ( 'not' p => ( 'not' r => q )) in TAUT
       by A2,LUKASI_1:3;
     ( 'not' r => q ) => ( 'not' q => r ) in TAUT by LUKASI_1:31;
then A4: 'not' p => (( 'not' r => q ) => ( 'not' q => r )) in TAUT by LUKASI_1:
13;
     ( 'not' p => (( 'not' r => q ) => ( 'not' q => r ))) => (( 'not' p => (
'not' r => q ))
       => ( 'not' p => ( 'not' q => r ))) in TAUT by LUKASI_1:11;
   then ( 'not' p => ( 'not' r => q )) => ( 'not' p => ( 'not' q => r )) in
TAUT
       by A4,CQC_THE1:82;
   then (( p 'or' q ) 'or' r ) => ( 'not' p => ( 'not' q => r )) in TAUT
       by A3,LUKASI_1:3;
   then (( p 'or' q ) 'or' r ) => ( 'not' p => ( q 'or' r )) in TAUT by Lm1;
   hence thesis by Lm1;
end;

theorem
    (( p '&' q ) '&' r ) => ( p '&' ( q '&' r )) in TAUT
proof
A1: 'not' ( p '&' ( q '&' r )) => ( 'not' p 'or' 'not'
 ( q '&' r ))in TAUT by Th17;
A2: 'not' ( q '&' r ) => ( 'not' q 'or' 'not' r ) in TAUT by Th17;
     ( 'not' q 'or' 'not' r ) => ( 'not' r 'or' 'not' q ) in TAUT by Th8;
   then 'not' ( q '&' r ) => ( 'not' r 'or' 'not'
 q ) in TAUT by A2,LUKASI_1:3;
then A3: 'not' 'not' p => ( 'not' ( q '&' r ) => ( 'not' r 'or' 'not'
 q )) in TAUT by LUKASI_1:13;
     ( 'not' 'not' p => ( 'not' ( q '&' r ) => ( 'not' r 'or' 'not' q ))) =>
   (( 'not' 'not' p => 'not' ( q '&' r )) => ( 'not' 'not' p => ( 'not' r 'or'
'not' q ))) in TAUT
         by LUKASI_1:11;
   then ( 'not' 'not' p => 'not' ( q '&' r )) => ( 'not' 'not' p => ( 'not' r
'or'
'not' q )) in TAUT
         by A3,CQC_THE1:82;
   then ( 'not' p 'or' 'not' ( q '&' r )) => ( 'not' 'not' p => ( 'not' r 'or'
'not'
 q )) in TAUT
         by Lm1;
   then ( 'not' p 'or' 'not' ( q '&' r )) => ( 'not' p 'or' ( 'not' r 'or'
'not'
 q )) in TAUT
         by Lm1;
then A4: 'not' ( p '&' ( q '&' r )) => ( 'not' p 'or' ( 'not' r 'or' 'not'
 q )) in TAUT
         by A1,LUKASI_1:3;
     ( 'not' p 'or' ( 'not' r 'or' 'not' q )) => (( 'not' r 'or' 'not' q ) 'or'
'not' p ) in TAUT
         by Th8;
then A5: 'not' ( p '&' ( q '&' r )) => (( 'not' r 'or' 'not' q ) 'or' 'not'
 p ) in TAUT
         by A4,LUKASI_1:3;
     (( 'not' r 'or' 'not' q ) 'or' 'not' p ) => ( 'not' r 'or' ( 'not' q 'or'
'not' p )) in TAUT
         by Th25;
then A6: 'not' ( p '&' ( q '&' r )) => ( 'not' r 'or' ( 'not' q 'or' 'not'
 p )) in TAUT
         by A5,LUKASI_1:3;
A7: ( 'not' q 'or' 'not' p ) => ( 'not' p 'or' 'not' q ) in TAUT by Th8;
     ( 'not' p 'or' 'not' q ) => 'not' ( p '&' q ) in TAUT by Th18;
   then ( 'not' q 'or' 'not' p ) => 'not'
 ( p '&' q ) in TAUT by A7,LUKASI_1:3;
then A8: 'not' 'not' r => (( 'not' q 'or' 'not' p ) => 'not'
 ( p '&' q )) in TAUT by LUKASI_1:13;
     ( 'not' 'not' r => (( 'not' q 'or' 'not' p ) => 'not' ( p '&' q ))) =>
   (( 'not' 'not' r => ( 'not' q 'or' 'not' p )) => ( 'not' 'not' r => 'not'
 ( p '&' q ))) in TAUT
         by LUKASI_1:11;
   then ( 'not' 'not' r => ( 'not' q 'or' 'not' p )) => ( 'not' 'not' r =>
'not'
 ( p '&' q )) in TAUT
         by A8,CQC_THE1:82;
   then ( 'not' r 'or' ( 'not' q 'or' 'not' p )) => ( 'not' 'not' r => 'not'
 ( p '&' q )) in TAUT
         by Lm1;
then A9: ( 'not' r 'or' ( 'not' q 'or' 'not' p )) => ( 'not' r 'or' 'not'
 ( p '&' q )) in TAUT by Lm1;
     ( 'not' r 'or' 'not' ( p '&' q )) => ( 'not' ( p '&' q ) 'or' 'not'
 r) in TAUT
         by Th8;
then A10: ( 'not' r 'or' ( 'not' q 'or' 'not' p )) => ( 'not' ( p '&' q ) 'or'
'not'
 r) in TAUT
         by A9,LUKASI_1:3;
     ( 'not' ( p '&' q ) 'or' 'not' r) => 'not' (( p '&' q ) '&' r ) in TAUT
         by Th18;
   then ( 'not' r 'or' ( 'not' q 'or' 'not' p )) => 'not'
 (( p '&' q ) '&' r ) in TAUT
         by A10,LUKASI_1:3;
   then 'not' ( p '&' ( q '&' r )) => 'not' (( p '&' q ) '&' r ) in TAUT
         by A6,LUKASI_1:3;
   hence thesis by LUKASI_1:35;
end;

theorem Th27:
  ( p 'or' ( q 'or' r )) => (( p 'or' q ) 'or' r ) in TAUT
proof
     ( p 'or' ( q 'or' r )) => ( 'not' p => ( q 'or' r )) in TAUT by Th5;
then A1: ( p 'or' ( q 'or' r )) => ( 'not' p => ( 'not' q => r )) in TAUT by
Lm1;
     ( 'not' q => r ) => ( 'not' r => q ) in TAUT by LUKASI_1:31;
then A2: 'not' p => (( 'not' q => r ) => ( 'not' r => q )) in TAUT by LUKASI_1:
13;
     ( 'not' p => (( 'not' q => r ) => ( 'not' r => q ))) => (( 'not' p => (
'not' q => r ))
   => ( 'not' p => ( 'not' r => q ))) in TAUT by LUKASI_1:11;
   then ( 'not' p => ( 'not' q => r )) => ( 'not' p => ( 'not' r => q )) in
TAUT
   by A2,CQC_THE1:82;
then A3: ( p 'or' ( q 'or' r )) => ( 'not' p => ( 'not'
 r => q )) in TAUT by A1,LUKASI_1:3;
     ( 'not' p => ( 'not' r => q )) => ( 'not' r => ( 'not'
 p => q )) in TAUT by LUKASI_1:8;
   then ( p 'or' ( q 'or' r )) => ( 'not' r => ( 'not' p => q )) in TAUT
    by A3,LUKASI_1:3;
then A4: ( p 'or' ( q 'or' r )) => ( r 'or' ( 'not' p => q )) in TAUT by Lm1;
     ( r 'or' ( 'not' p => q )) => (( 'not' p => q ) 'or' r) in TAUT by Th8;
   then ( p 'or' ( q 'or' r )) => (( 'not'
 p => q ) 'or' r) in TAUT by A4,LUKASI_1:3;
   hence thesis by Lm1;
end;

theorem Th28:
  p => ( q => ( p '&' q )) in TAUT
proof
       'not' ( p '&' q ) => ( 'not' p 'or' 'not' q ) in TAUT by Th17;
   then A1: ( p '&' q ) 'or' ( 'not' p 'or' 'not' q ) in TAUT by Lm1;
        ( p '&' q ) 'or' ( 'not' p 'or' 'not' q ) =>
      ((( p '&' q ) 'or' 'not' p ) 'or' 'not' q ) in TAUT by Th27;
   then A2: ((( p '&' q ) 'or' 'not' p ) 'or' 'not' q ) in TAUT by A1,CQC_THE1:
82;
        ((( p '&' q ) 'or' 'not' p ) 'or' 'not' q ) =>
      ( 'not' q 'or' (( p '&' q ) 'or' 'not' p )) in TAUT by Th8;
      then ( 'not' q 'or' (( p '&' q ) 'or' 'not'
 p )) in TAUT by A2,CQC_THE1:82;
   then A3: ( 'not' 'not' q => (( p '&' q ) 'or' 'not' p )) in TAUT by Lm1;
        q => 'not' 'not' q in TAUT by LUKASI_1:27;
   then A4: ( q => (( p '&' q ) 'or' 'not' p )) in TAUT by A3,LUKASI_1:3;
        (( p '&' q ) 'or' 'not' p ) => ( 'not' p 'or' ( p '&' q )) in TAUT
      by Th8;
   then A5: q => ((( p '&' q ) 'or' 'not' p ) => ( 'not'
 p 'or' ( p '&' q ))) in TAUT
      by LUKASI_1:13;
        (q => ((( p '&' q ) 'or' 'not' p ) => ( 'not' p 'or' ( p '&' q )))) =>
      ((q => ( p '&' q ) 'or' 'not' p ) => ( q => ( 'not'
 p 'or' ( p '&' q )))) in TAUT
      by LUKASI_1:11;
      then (q => ( p '&' q ) 'or' 'not' p ) => ( q => ( 'not'
 p 'or' ( p '&' q ))) in TAUT
      by A5,CQC_THE1:82;
      then ( q => ( 'not' p 'or' ( p '&' q ))) in TAUT by A4,CQC_THE1:82;
      then ( q => ( 'not' 'not' p => ( p '&' q ))) in TAUT by Lm1;
   then A6: 'not' 'not' p => ( q => ( p '&' q )) in TAUT by LUKASI_1:15;
        p => 'not' 'not' p in TAUT by LUKASI_1:27;
      hence thesis by A6,LUKASI_1:3;
end;

theorem
    ( p => q ) => (( q => p ) => ( p <=> q )) in TAUT
proof
    ( p => q ) => (( q => p ) => (( p => q ) '&' ( q => p ))) in TAUT by Th28;
  hence thesis by QC_LANG2:def 4;
end;

Lm4:  p in TAUT & q in TAUT implies p '&' q in TAUT
proof
  assume that
            A1: p in TAUT and
            A2: q in TAUT;
                  p => ( q => ( p '&' q )) in TAUT by Th28;
                then q => ( p '&' q ) in TAUT by A1,CQC_THE1:82;
                hence thesis by A2,CQC_THE1:82;
end;

theorem
    ( p 'or' q ) <=> ( q 'or' p ) in TAUT
proof
     set P = p 'or' q;
     set Q = q 'or' p;
     A1: P => Q in TAUT by Th8;
          Q => P in TAUT by Th8;
        then ( P => Q ) '&' ( Q => P ) in TAUT by A1,Lm4;
        hence thesis by QC_LANG2:def 4;
end;

theorem
    (( p '&' q ) => r ) => ( p => ( q => r )) in TAUT
proof
       ( q => ( p '&' q )) => ((( p '&' q ) => r ) => ( q => r )) in TAUT
     by LUKASI_1:1;
  then A1: p => (( q => ( p '&' q )) => ((( p '&' q ) => r ) => ( q => r ))) in
TAUT
     by LUKASI_1:13;
       p => ( q => ( p '&' q )) in TAUT by Th28;
  then A2: p => ((( p '&' q ) => r ) => ( q => r )) in TAUT by A1,LUKASI_1:20;
       (p => ((( p '&' q ) => r ) => ( q => r ))) =>
     ((( p '&' q ) => r ) => ( p => ( q => r ))) in TAUT by LUKASI_1:8;
     hence thesis by A2,CQC_THE1:82;
end;

theorem Th32:
  ( p => ( q => r )) => (( p '&' q ) => r ) in TAUT
proof
  A1: ( p '&' q ) => q in TAUT by Th21;
       (( p '&' q ) => q) => (( q => r ) => (( p '&' q ) => r )) in TAUT
     by LUKASI_1:1;
     then ( q => r ) => (( p '&' q ) => r ) in TAUT by A1,CQC_THE1:82;
  then A2: p => (( q => r ) => (( p '&' q ) => r )) in TAUT by LUKASI_1:13;
       p => (( q => r ) => (( p '&' q ) => r )) =>
     ((p => ( q => r )) => ( p => (( p '&' q ) => r ))) in TAUT
     by LUKASI_1:11;
  then A3: (p => ( q => r )) => ( p => (( p '&' q ) => r )) in TAUT
     by A2,CQC_THE1:82;
       ( p => (( p '&' q ) => r )) => ((p '&' q ) => ( p => r )) in TAUT
     by LUKASI_1:8;
  then A4: (p => ( q => r )) => ((p '&' q ) => ( p => r )) in TAUT
     by A3,LUKASI_1:3;
  A5: ((p '&' q ) => ( p => r )) => ((( p '&' q ) => p ) => (( p '&' q )
     => r )) in TAUT by LUKASI_1:11;
       ( p '&' q ) => p in TAUT by Th19;
     then ((p '&' q ) => ( p => r )) => (( p '&' q ) => r ) in TAUT
     by A5,LUKASI_1:16;
     hence thesis by A4,LUKASI_1:3;
end;

theorem Th33:
  ( r => p ) => (( r => q ) => ( r => ( p '&' q ))) in TAUT
proof
       p => ( q => ( p '&' q )) in TAUT by Th28;
  then A1: r => ( p => ( q => ( p '&' q ))) in TAUT by LUKASI_1:13;
       (r => ( p => ( q => ( p '&' q )))) =>
     (( r => p ) => ( r => ( q => ( p '&' q )))) in TAUT
     by LUKASI_1:11;
  then A2: ( r => p ) => ( r => ( q => ( p '&' q ))) in TAUT by A1,CQC_THE1:82;
       ( r => ( q => ( p '&' q ))) => (( r => q ) => ( r => ( p '&' q )))
     in TAUT by LUKASI_1:11;
     hence thesis by A2,LUKASI_1:3;
end;

theorem
    (( p 'or' q ) => r ) => (( p => r ) 'or' ( q => r )) in TAUT
proof
  A1: q => ( p 'or' q ) in TAUT by Th4;
       ( q => ( p 'or' q )) => ((( p 'or' q ) => r ) => ( q => r )) in TAUT
     by LUKASI_1:1;
     then (( p 'or' q ) => r ) => ( q => r ) in TAUT by A1,CQC_THE1:82;
     then 'not' ( p => r ) => ((( p 'or' q ) => r ) => ( q => r )) in TAUT
     by LUKASI_1:13;
     then (( p 'or' q ) => r ) => ( 'not' ( p => r ) => ( q => r )) in TAUT
     by LUKASI_1:15;
     hence thesis by Lm1;
end;

theorem Th35:
  ( p => r ) => (( q => r ) => (( p 'or' q ) => r)) in TAUT
proof
     set A = ( 'not' r => 'not' p );
     set B = ( 'not' r => 'not' q );
     set C = ( 'not' r => ( 'not' p '&' 'not' q ));
     set D = (( p 'or' q ) => r );
     set E = q => r;
  A1: A => ( B => C) in TAUT by Th33;
       C => ('not' ( 'not' p '&' 'not' q ) => r ) in TAUT by LUKASI_1:31;
     then C => D in TAUT by QC_LANG2:def 3;
  then A2: B => ( C => D ) in TAUT by LUKASI_1:13;
       B => ( C => D ) => (( B => C ) => ( B => D )) in TAUT by LUKASI_1:11;
     then ( B => C ) => ( B => D ) in TAUT by A2,CQC_THE1:82;
     then A => ( B => D ) in TAUT by A1,LUKASI_1:3;
  then A3: B => ( A => D ) in TAUT by LUKASI_1:15;
       E => B in TAUT by LUKASI_1:26;
     then E => ( A => D ) in TAUT by A3,LUKASI_1:3;
  then A4: A => ( E => D ) in TAUT by LUKASI_1:15;
       (p => r) => A in TAUT by LUKASI_1:26;
     hence thesis by A4,LUKASI_1:3;
end;

theorem Th36:
  (( p => r ) '&' ( q => r )) => (( p 'or' q ) => r) in TAUT
proof
     set P = ( p => r );
     set Q = ( q => r );
     set R = (( p 'or' q ) => r);
  A1: P => ( Q => R ) in TAUT by Th35;
       (P => ( Q => R )) => (( P '&' Q ) => R ) in TAUT by Th32;
     hence thesis by A1,CQC_THE1:82;
end;

theorem
    ( p => ( q '&' 'not' q )) => 'not' p in TAUT
proof
       'not' ( q '&' 'not' q ) in TAUT by Th1;
     then p => 'not' ( q '&' 'not' q ) in TAUT by LUKASI_1:13;
  then A1: 'not' 'not' ( q '&' 'not' q ) => 'not' p in TAUT by LUKASI_1:34;
       ( q '&' 'not' q ) => 'not' 'not' ( q '&' 'not'
 q ) in TAUT by LUKASI_1:27;
     then ( q '&' 'not' q ) => 'not' p in TAUT by A1,LUKASI_1:3;
  then A2: p => (( q '&' 'not' q ) => 'not' p) in TAUT by LUKASI_1:13;
       p => (( q '&' 'not' q ) => 'not' p) => (( p => ( q '&' 'not'
 q )) => ( p => 'not' p ))
     in TAUT by LUKASI_1:11;
  then A3: ( p => ( q '&' 'not' q )) => ( p => 'not'
 p ) in TAUT by A2,CQC_THE1:82;
  A4: ( 'not' 'not' p => 'not' p ) => 'not' p in TAUT by CQC_THE1:78;
  A5: 'not' 'not' p => p in TAUT by LUKASI_1:25;
       ( 'not' 'not' p => p ) => (( p => 'not' p ) => ( 'not' 'not' p => 'not'
 p )) in TAUT
     by LUKASI_1:1;
     then ( p => 'not' p ) => ( 'not' 'not' p => 'not'
 p ) in TAUT by A5,CQC_THE1:82;
     then ( p => 'not' p ) => 'not' p in TAUT by A4,LUKASI_1:3;
     hence thesis by A3,LUKASI_1:3;
end;

theorem
    (( p 'or' q ) '&' ( p 'or' r )) => ( p 'or' ( q '&' r )) in TAUT
proof
     ( 'not' p => q ) => (( 'not' p => r ) => ( 'not' p => ( q '&' r ))) in
TAUT
   by Th33;
   then ( p 'or' q ) => (( 'not' p => r ) => ( 'not' p => ( q '&' r ))) in
TAUT
   by Lm1;
   then ( p 'or' q ) => (( p 'or' r ) => ( 'not' p => ( q '&' r ))) in TAUT
   by Lm1;
then A1: ( p 'or' q ) => (( p 'or' r ) => ( p 'or' ( q '&' r ))) in TAUT by Lm1
;
     (( p 'or' q ) => (( p 'or' r ) => ( p 'or' ( q '&' r )))) =>
   ((( p 'or' q ) '&' ( p 'or' r )) => ( p 'or' ( q '&' r ))) in TAUT
   by Th32;
   hence thesis by A1,CQC_THE1:82;
end;

theorem
    ( p '&' ( q 'or' r )) => (( p '&' q ) 'or' ( p '&' r )) in TAUT
proof
  A1: ( p => 'not' q ) => (( p => 'not' r ) => ( p => ( 'not' q '&' 'not'
 r ))) in TAUT
     by Th33;
       ( p => ( 'not' q '&' 'not' r )) = 'not' ( p '&' 'not' ( 'not' q '&'
'not'
 r ))
     by QC_LANG2:def 2;
  then A2: ( p => 'not' q ) => (( p => 'not' r ) => 'not'
 ( p '&' ( q 'or' r ))) in TAUT
     by A1,QC_LANG2:def 3;
  A3: 'not' ( p => 'not' q ) => ( p '&' q ) in TAUT by Th16;
       ('not' ( p => 'not' q ) => ( p '&' q )) =>
     ( 'not' ( p '&' q ) => ( p => 'not' q )) in TAUT by LUKASI_1:31;
     then 'not' ( p '&' q ) => ( p => 'not' q ) in TAUT by A3,CQC_THE1:82;
     then 'not' ( p '&' q ) => (( p => 'not' r ) => 'not'
 ( p '&' ( q 'or' r ))) in TAUT
     by A2,LUKASI_1:3;
  then A4: ( p => 'not' r ) => ( 'not' ( p '&' q ) => 'not'
 ( p '&' ( q 'or' r ))) in TAUT
     by LUKASI_1:15;
  A5: 'not' ( p => 'not' r ) => ( p '&' r ) in TAUT by Th16;
       ('not' ( p => 'not' r ) => ( p '&' r )) =>
     ( 'not' ( p '&' r ) => ( p => 'not' r )) in TAUT by LUKASI_1:31;
     then 'not' ( p '&' r ) => ( p => 'not' r ) in TAUT by A5,CQC_THE1:82;
     then 'not' ( p '&' r ) => ('not' ( p '&' q ) => 'not'
 ( p '&' ( q 'or' r ))) in TAUT
     by A4,LUKASI_1:3;
  then A6: 'not' ( p '&' q ) => ('not' ( p '&' r ) => 'not'
 ( p '&' ( q 'or' r ))) in TAUT
     by LUKASI_1:15;
      ( 'not' ( p '&' q ) => ('not' ( p '&' r ) => 'not'
 ( p '&' ( q 'or' r )))) =>
    ((( 'not' ( p '&' q ) '&' 'not' ( p '&' r )) => 'not'
 ( p '&' ( q 'or' r ))))
    in TAUT by Th32;
 then A7: ( 'not' ( p '&' q ) '&' 'not' ( p '&' r )) => 'not'
 ( p '&' ( q 'or' r )) in TAUT
    by A6,CQC_THE1:82;
      'not' (( p '&' q ) 'or' ( p '&' r )) => ( 'not' ( p '&' q ) '&' 'not'
 ( p '&' r ))
    in TAUT by Th6;
    then 'not' (( p '&' q ) 'or' ( p '&' r )) => 'not' ( p '&' ( q 'or' r ))
in TAUT
    by A7,LUKASI_1:3;
    hence thesis by LUKASI_1:35;
end;

theorem Th40:
  (( p 'or' r ) '&' ( q 'or' r )) => (( p '&' q ) 'or' r ) in TAUT
proof
       (( 'not' p => r ) '&' ( 'not' q => r )) => (( 'not' p 'or' 'not'
 q ) => r) in TAUT
     by Th36;
     then (( p 'or' r ) '&' ( 'not' q => r )) => (( 'not' p 'or' 'not'
 q ) => r) in TAUT
     by Lm1;
  then A1: (( p 'or' r ) '&' ( q 'or' r )) => (( 'not' p 'or' 'not'
 q ) => r) in TAUT
     by Lm1;
  A2: 'not' ( p '&' q ) => ( 'not' p 'or' 'not' q ) in TAUT by Th17;
       ( 'not' ( p '&' q ) => ( 'not' p 'or' 'not' q )) =>
     ((( 'not' p 'or' 'not' q ) => r) => ( 'not' ( p '&' q ) => r )) in TAUT
     by LUKASI_1:1;
     then (( 'not' p 'or' 'not' q ) => r) => ( 'not' ( p '&' q ) => r ) in
TAUT
     by A2,CQC_THE1:82;
     then (( p 'or' r ) '&' ( q 'or' r )) => ( 'not' ( p '&' q ) => r ) in
TAUT
     by A1,LUKASI_1:3;
     hence thesis by Lm1;
end;

Lm5:  p => q in TAUT implies ( r '&' p ) => ( r '&' q ) in TAUT
proof
     assume
             p => q in TAUT;
           then 'not' q => 'not' p in TAUT by LUKASI_1:34;
        then A1: r => ( 'not' q => 'not' p ) in TAUT by LUKASI_1:13;
             ( r => ( 'not' q => 'not' p )) =>
           (( r => 'not' q ) => ( r => 'not' p )) in TAUT by LUKASI_1:11;
           then ( r => 'not' q ) => ( r => 'not'
 p ) in TAUT by A1,CQC_THE1:82;
        then A2: 'not' ( r => 'not' p ) => 'not' ( r => 'not'
 q ) in TAUT by LUKASI_1:34;
             ( r '&' p ) => 'not' ( r => 'not' p ) in TAUT by Th15;
        then A3: ( r '&' p ) => 'not' ( r => 'not' q ) in TAUT by A2,LUKASI_1:3
;
             'not' ( r => 'not' q ) => ( r '&' q ) in TAUT by Th16;
           hence thesis by A3,LUKASI_1:3;
end;

Lm6:  p => q in TAUT implies ( p 'or' r ) => ( q 'or' r ) in TAUT
proof
     assume
             p => q in TAUT;
        then A1: 'not' q => 'not' p in TAUT by LUKASI_1:34;
             ( 'not' q => 'not' p ) => (( 'not' p => r ) => ( 'not'
 q => r )) in TAUT
           by LUKASI_1:1;
           then ( 'not' p => r ) => ( 'not'
 q => r ) in TAUT by A1,CQC_THE1:82;
           then ( p 'or' r ) => ( 'not' q => r ) in TAUT by Lm1;
           hence thesis by Lm1;
end;

Lm7:  p => q in TAUT implies ( r 'or' p ) => ( r 'or' q ) in TAUT
proof
     assume
             p => q in TAUT;
        then A1: 'not' r => ( p => q ) in TAUT by LUKASI_1:13;
             'not' r => ( p => q ) => (( 'not' r => p ) => ( 'not'
 r => q )) in TAUT
           by LUKASI_1:11;
           then ( 'not' r => p ) => ( 'not'
 r => q ) in TAUT by A1,CQC_THE1:82;
           then ( r 'or' p ) => ( 'not' r => q ) in TAUT by Lm1;
           hence thesis by Lm1;
end;

theorem
    (( p 'or' q ) '&' r ) => (( p '&' r ) 'or' ( q '&' r )) in TAUT
proof
       (( 'not' p 'or' 'not' r ) '&' ( 'not' q 'or' 'not' r )) =>
     (( 'not' p '&' 'not' q ) 'or' 'not' r ) in TAUT by Th40;
  then A1: 'not' (( 'not' p '&' 'not' q ) 'or' 'not' r ) =>
     'not' (( 'not' p 'or' 'not' r ) '&' ( 'not' q 'or' 'not'
 r )) in TAUT by LUKASI_1:34;
       ( 'not' ( 'not' p '&' 'not' q ) '&' 'not' 'not' r ) => 'not' (( 'not'
 p '&' 'not' q ) 'or' 'not' r )
     in TAUT by Th7;
     then ( 'not' ( 'not' p '&' 'not' q ) '&' 'not' 'not' r ) =>
     'not' (( 'not' p 'or' 'not' r ) '&' ( 'not' q 'or' 'not'
 r )) in TAUT by A1,LUKASI_1:3;
  then A2: (( p 'or' q ) '&' 'not' 'not' r ) =>
     'not' (( 'not' p 'or' 'not' r ) '&' ( 'not' q 'or' 'not'
 r )) in TAUT by QC_LANG2:def 3;
       r => 'not' 'not' r in TAUT by LUKASI_1:27;
     then (( p 'or' q ) '&' r ) => (( p 'or' q ) '&' 'not' 'not'
 r ) in TAUT by Lm5;
  then A3: (( p 'or' q ) '&' r ) =>
     'not' (( 'not' p 'or' 'not' r ) '&' ( 'not' q 'or' 'not'
 r )) in TAUT by A2,LUKASI_1:3;
       'not' (( 'not' p 'or' 'not' r ) '&' ( 'not' q 'or' 'not' r )) =>
     ('not' ( 'not' p 'or' 'not' r ) 'or' 'not' ( 'not' q 'or' 'not'
 r )) in TAUT by Th17;
  then A4: (( p 'or' q ) '&' r ) =>
     ('not' ( 'not' p 'or' 'not' r ) 'or' 'not' ( 'not' q 'or' 'not'
 r )) in TAUT
     by A3,LUKASI_1:3;
  A5: 'not' ( p '&' r ) => ( 'not' p 'or' 'not' r ) in TAUT by Th17;
       ( 'not' ( p '&' r ) => ( 'not' p 'or' 'not' r )) =>
     ( 'not' ( 'not' p 'or' 'not'
 r ) => ( p '&' r )) in TAUT by LUKASI_1:31;
     then 'not' ( 'not' p 'or' 'not'
 r ) => ( p '&' r ) in TAUT by A5,CQC_THE1:82;
     then ( 'not' ( 'not' p 'or' 'not' r ) 'or' 'not' ( 'not' q 'or' 'not' r )
) =>
     (( p '&' r ) 'or' 'not' ( 'not' q 'or' 'not' r )) in TAUT by Lm6;
  then A6: (( p 'or' q ) '&' r ) =>
     (( p '&' r ) 'or' 'not' ( 'not' q 'or' 'not'
 r )) in TAUT by A4,LUKASI_1:3;
  A7: 'not' ( q '&' r ) => ( 'not' q 'or' 'not' r ) in TAUT by Th17;
       ( 'not' ( q '&' r ) => ( 'not' q 'or' 'not' r )) =>
     ( 'not' ( 'not' q 'or' 'not'
 r ) => ( q '&' r )) in TAUT by LUKASI_1:31;
     then 'not' ( 'not' q 'or' 'not'
 r ) => ( q '&' r ) in TAUT by A7,CQC_THE1:82;
     then (( p '&' r ) 'or' 'not' ( 'not' q 'or' 'not' r )) =>
     (( p '&' r ) 'or' ( q '&' r )) in TAUT by Lm7;
     hence thesis by A6,LUKASI_1:3;
end;

          ::::::::::::::::::::::::::::::::::::::::::::
          ::   R E G U L Y   D O W O D Z E N I A    ::
          ::::::::::::::::::::::::::::::::::::::::::::

theorem
    p in TAUT implies ( p 'or' q ) in TAUT
proof
     assume
           A1: p in TAUT;
                p => ( p 'or' q ) in TAUT by Th3;
              hence thesis by A1,CQC_THE1:82;
end;

theorem
    q in TAUT implies ( p 'or' q ) in TAUT
proof
     assume
           A1: q in TAUT;
                q => ( p 'or' q ) in TAUT by Th4;
              hence thesis by A1,CQC_THE1:82;
end;

theorem
    ( p '&' q ) in TAUT implies p in TAUT
proof
     assume
           A1: ( p '&' q ) in TAUT;
                ( p '&' q ) => p in TAUT by Th19;
              hence thesis by A1,CQC_THE1:82;
end;

theorem
    ( p '&' q ) in TAUT implies q in TAUT
proof
     assume
           A1: ( p '&' q ) in TAUT;
                ( p '&' q ) => q in TAUT by Th21;
              hence thesis by A1,CQC_THE1:82;
end;

theorem
    ( p '&' q ) in TAUT implies ( p 'or' q ) in TAUT
proof
     assume
           A1: ( p '&' q ) in TAUT;
                ( p '&' q ) => ( p 'or' q ) in TAUT by Th20;
              hence thesis by A1,CQC_THE1:82;
end;

theorem
   p in TAUT & q in TAUT implies p '&' q in TAUT by Lm4;

theorem
   p => q in TAUT implies ( p 'or' r ) => ( q 'or' r ) in TAUT by Lm6;

theorem
   p => q in TAUT implies ( r 'or' p ) => ( r 'or' q ) in TAUT by Lm7;

theorem
   p => q in TAUT implies ( r '&' p ) => ( r '&' q ) in TAUT by Lm5;

theorem Th51:
  p => q in TAUT implies ( p '&' r ) => ( q '&' r ) in TAUT
proof
     assume
        A1:  p => q in TAUT;
              ( p => q ) => (( q => 'not' r ) => ( p => 'not' r )) in TAUT
            by LUKASI_1:1;
            then ( q => 'not' r ) => ( p => 'not'
 r ) in TAUT by A1,CQC_THE1:82;
        then A2:  'not' ( p => 'not' r ) => 'not' ( q => 'not'
 r ) in TAUT by LUKASI_1:34;
              ( p '&' r ) => 'not' ( p => 'not' r ) in TAUT by Th15;
        then A3:  ( p '&' r ) => 'not' ( q => 'not' r ) in TAUT by A2,LUKASI_1:
3;
              'not' ( q => 'not' r ) => ( q '&' r ) in TAUT by Th16;
            hence thesis by A3,LUKASI_1:3;
end;

theorem
    r => p in TAUT & r => q in TAUT implies r => ( p '&' q ) in TAUT
proof
     assume that
            A1: r => p in TAUT and
            A2: r => q in TAUT;
                  ( r => p ) => (( r => q ) => ( r => ( p '&' q ))) in TAUT
                by Th33;
                then ( r => q ) => ( r => ( p '&' q )) in TAUT by A1,CQC_THE1:
82;
                hence thesis by A2,CQC_THE1:82;
end;

theorem
    p => r in TAUT & q => r in TAUT implies ( p 'or' q ) => r in TAUT
proof
     assume
             p => r in TAUT & q => r in TAUT;
        then A1: ( p => r ) '&' ( q => r ) in TAUT by Lm4;
             (( p => r ) '&' ( q => r )) => (( p 'or' q ) => r) in TAUT
           by Th36;
           hence thesis by A1,CQC_THE1:82;
end;

theorem
    ( p 'or' q ) in TAUT & 'not' p in TAUT implies q in TAUT
proof
     assume that
             A1: ( p 'or' q ) in TAUT and
             A2: 'not' p in TAUT;
                   ( p 'or' q ) => ( 'not' p => q ) in TAUT by Th5;
                  then 'not' p => q in TAUT by A1,CQC_THE1:82;
                  hence thesis by A2,CQC_THE1:82;
end;

theorem
    ( p 'or' q ) in TAUT & 'not' q in TAUT implies p in TAUT
proof
     assume that
             A1: ( p 'or' q ) in TAUT and
             A2: 'not' q in TAUT;
              A3: ( q 'or' p ) => ( 'not' q => p ) in TAUT by Th5;
                   ( p 'or' q ) => ( q 'or' p ) in TAUT by Th8;
                 then ( p 'or' q ) => ( 'not'
 q => p ) in TAUT by A3,LUKASI_1:3;
                 then 'not' q => p in TAUT by A1,CQC_THE1:82;
                 hence thesis by A2,CQC_THE1:82;
end;

theorem
    p => q in TAUT & r => s in TAUT implies ( p '&' r ) => ( q '&' s ) in TAUT
proof
     assume that
             A1: p => q in TAUT and
             A2: r => s in TAUT;
              A3: ( p '&' r ) => ( q '&' r ) in TAUT by A1,Th51;
                   ( q '&' r ) => ( q '&' s ) in TAUT by A2,Lm5;
                 hence thesis by A3,LUKASI_1:3;
end;

theorem
    p => q in TAUT & r => s in TAUT implies ( p 'or' r ) => ( q 'or' s ) in
TAUT
proof
     assume that
             A1: p => q in TAUT and
             A2: r => s in TAUT;
              A3: ( p 'or' r ) => ( q 'or' r ) in TAUT by A1,Lm6;
                   ( q 'or' r ) => ( q 'or' s ) in TAUT by A2,Lm7;
                 hence thesis by A3,LUKASI_1:3;
end;

theorem
    ( p '&' 'not' q ) => 'not' p in TAUT implies p => q in TAUT
proof
 assume
        ( p '&' 'not' q ) => 'not' p in TAUT;
     then A1: 'not' 'not' p => 'not' ( p '&' 'not' q ) in TAUT by LUKASI_1:34;
          p => 'not' 'not' p in TAUT by LUKASI_1:27;
     then A2: p => 'not' ( p '&' 'not' q ) in TAUT by A1,LUKASI_1:3;
        'not' ( p '&' 'not' q ) = ( p => q ) by QC_LANG2:def 2;
        then 'not' ( p '&' 'not' q ) => ( p => q ) in TAUT by LUKASI_1:4;
     then A3: p => ( 'not' ( p '&' 'not' q ) => ( p => q )) in TAUT by LUKASI_1
:13;
          ( p => ( 'not' ( p '&' 'not' q ) => ( p => q ))) =>
        (( p => 'not' ( p '&' 'not' q )) => ( p => ( p => q ))) in TAUT
        by LUKASI_1:11;
        then ( p => 'not' ( p '&' 'not' q )) => ( p => ( p => q )) in TAUT
        by A3,CQC_THE1:82;
        then p => ( p => q ) in TAUT by A2,CQC_THE1:82;
        hence thesis by LUKASI_1:18;
end;

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