public void set(int x, int y, int value){
		if (board[x][y].get_value()==EMPTY_PIECE){
			board[x][y].set_value(value);
			n_cell++;
			if (value == WHITE_PIECE) ++WHITE_SCORE;
			else ++BLACK_SCORE;
		}else if (board[x][y].get_value()==WHITE_PIECE){
			board[x][y].set_value(value);
			WHITE_SCORE--;
			BLACK_SCORE++;
		}else{
			board[x][y].set_value(value);
			WHITE_SCORE++;
			BLACK_SCORE--;
		}
		resetSuggest();
		this.setChanged();
		this.notifyObservers();
	} // end set