theorem
  ( p '&' q ) in TAUT(A) implies ( p 'or' q ) in TAUT(A)
proof
  assume
A1: ( p '&' q ) in TAUT(A);
  ( p '&' q ) => ( p 'or' q ) in TAUT(A) by Th20;
  hence thesis by A1,CQC_THE1:46;
end;
