theorem Th64:
  r|= 'not' H iff r|/= H
proof
  r|= 'not' H iff r|= 'not' Evaluate(H,AtomicKai) by Th50;
  then r|= 'not' H iff r|/= Evaluate(H,AtomicKai) by Th57;
  hence thesis;
end;
