/** interface Sortable should be implemented at each Object used in
 * the Constants.quickSort() algorithm. In this project classes SortMbr
 * and BranchList implement it.
 */
public interface Sortable
{
		// returns true if this<s according to the sortCriterion
		public abstract boolean lessThan(Sortable s, int sortCriterion);
		
		// returns true if this>s according to the sortCriterion
		public abstract boolean greaterThan(Sortable s, int sortCriterion);
}