private Node normaliseRightResidualPath() throws MVDException
	{
		Node arcTo = arc.to;
		arc.to.removeIncoming( arc );
		if ( rightSubArc != null )
		{
			arcTo.addIncoming( rightSubArc );
			arcTo = new Node();
			arcTo.addOutgoing( rightSubArc );
		}
		if ( rightSubGraph == null )
		{
			if ( arcTo != graph.end )
				rightSubGraph = createEmptyRightSubgraph();
			// else nothing to do
		}
		else	// rightSubGraph != null
		{
			if ( arcTo == graph.end )
			{
				Arc a = createEmptyArc( version );
				arcTo.addIncoming( a );
				arcTo = new Node();
				arcTo.addOutgoing( a );
			}
			// else there's already a residual path
		}
		return arcTo;
	}