public boolean isTop( int row, int column ) {
	if ( row < 0 || column < 0 || row > 5 || column > 6 ) {
	    return false;
	}
	if ( _board[row][column] == 0 && ( (row + 1) > 5 || _board[row+1][column] != 0)) {
	    return true;
	}
	return false;
    }