public void capture (int i, int j, Node n)
	// capture neighboring groups without liberties
	// capture own group on suicide
	{
		int c = -P.color(i, j);
		captured = 0;
		if (i > 0) capturegroup(i - 1, j, c, n);
		if (j > 0) capturegroup(i, j - 1, c, n);
		if (i < S - 1) capturegroup(i + 1, j, c, n);
		if (j < S - 1) capturegroup(i, j + 1, c, n);
		if (P.color(i, j) == -c)
		{
			capturegroup(i, j, -c, n);
		}
		if (captured == 1 && P.count(i, j) != 1) captured = 0;
		if ( !GF.getParameter("korule", true)) captured = 0;
	}