/** Returns the intersection of this set and the parameter */
    public SetADT<T> intersection(SetADT<T> set);

    /** Returns true if this set is a subset of the parameter */
    public boolean subset(SetADT<T> set);

    /** Returns the set difference of this and the parameter.
     *  That is the set of elements in here but not in the parameter set */
    public SetADT<T> diff(SetADT<T> set);