reserve Y for non empty set;
reserve Y for non empty set;
reserve Y for non empty set;
reserve Y for non empty set,
  a,b,c,d,e,f,g for Function of Y,BOOLEAN;

theorem
  a '&' b '&' c '&' d '&' e '&' f '&' g '<' a & a '&' b '&' c '&' d '&'
  e '&' f '&' g '<' b by Lm6;
