private void getSpecialArcs()
	{
		Node leftFrom = arc.from;
		while ( leftFrom != graph.start )
		{
			if ( leftSpecialArcs == null )
				leftSpecialArcs = new SimpleQueue<SpecialArc>();
			Arc a = leftFrom.pickIncomingArc( version );
			if ( a instanceof SpecialArc )
				leftSpecialArcs.add( (SpecialArc)a );
			leftFrom = a.from;
		}
		Node rightTo = arc.to;
		while ( rightTo != graph.end )
		{
			if ( rightSpecialArcs == null )
				rightSpecialArcs = new SimpleQueue<SpecialArc>();
			Arc a = rightTo.pickOutgoingArc( version );
			if ( a instanceof SpecialArc )
				rightSpecialArcs.add( (SpecialArc)a );
			rightTo = a.to;
		}
	}