void gotovariation (int i, int j)
	// goto the variation at (i,j)
	{
		TreeNode newpos = P.tree(i, j);
		getinformation();
		if (VCurrent && newpos.parentPos() == Pos.parentPos())
		{
			goback();
			Pos = newpos;
			setnode();
			setlast();
		}
		else if ( !VCurrent && newpos.parentPos() == Pos)
		{
			Pos = newpos;
			setnode();
			setlast();
		}
		copy();
		showinformation();
	}