PositiveSet : set of int ->set of intPositiveSet(setIn) == { Abs(x)| x in set setIn};

BiggestSet : set of int * set of int -> set of intBiggestSet(s1, s2) == if card(s1)> card(s2)then s1else s2pre card(s1 inter s2) = 0;

IsAllBigger : set of int * set of int -> boolIsAllBigger(s1,s2) == forall jin sets1, k in sets2& (j>k)pre card(s1) >0 andcard(s2) >0;