edge moveUpRight()
	{
		edge f = this;
		while ((null != f) && ( f.tail.leftEdge != f))
			f = f.tail.parentEdge;
		//go up the tree until f is a leftEdge
		if ( null == f )
			return f; //triggered at end of search
		else
			return(f.tail.rightEdge);      
		//and then go right
	}