abstract public class BoardSuccessorsAbstract {

	private Board SuccessorsList[] = new Board[4];
	private int NumofSuccessors;
	
	// make sure the default constructor sets the initial count of
	// successors to 0

	abstract public void AddBoard(Board NewBoard);
	// adds a new board NewBoard to the list of successors

	abstract public Board popBoard();
	// returns a board from the list of siccessors and decrements
	// count of successors

	abstract public int NumSuccessors();
	// returns number of unpopped successors left.
}