示例#1
0
void parallelFreeSort(const Graph &G, SListPure<edge> &edges)
{
    G.allEdges(edges);

    BucketSourceIndex bucketSrc;
    edges.bucketSort(0,G.maxNodeIndex(),bucketSrc);

    BucketTargetIndex bucketTgt;
    edges.bucketSort(0,G.maxNodeIndex(),bucketTgt);
}
示例#2
0
// compute the separated DFS children for all nodes in ascending order of
// their lowpoint values in linear time
void BoyerMyrvoldInit::computeDFSChildLists() {
	// Bucketsort by lowpoint values
	BucketLowPoint blp(m_lowPoint);

	// copy all non-virtual nodes in a list and sort them with Bucketsort
	SListPure<node> allNodes;
	for (node v : m_g.nodes) {
		if (m_dfi[v] > 0)
			allNodes.pushBack(v);
	}
	allNodes.bucketSort(1, m_nodeFromDFI.high(), blp);

	// build DFS-child list
	for (node v : allNodes) {
		OGDF_ASSERT(m_dfi[v] > 0);

		// if node is not root: insert node after last element of parent's DFSChildList
		// to achieve constant time deletion later:
		// set a pointer for each node to predecessor of his representative in the list
		if (m_adjParent[v] != nullptr) {
			OGDF_ASSERT(m_realVertex[m_adjParent[v]->theNode()] != nullptr);

			m_pNodeInParent[v] = m_separatedDFSChildList[m_realVertex[m_adjParent[v]->theNode()]].pushBack(v);

			OGDF_ASSERT(m_pNodeInParent[v].valid());
			OGDF_ASSERT(v == *m_pNodeInParent[v]);
		}
		else m_pNodeInParent[v] = nullptr;
	}
}
示例#3
0
void parallelFreeSortUndirected(const Graph &G,
                                SListPure<edge> &edges,
                                EdgeArray<int> &minIndex,
                                EdgeArray<int> &maxIndex)
{
    G.allEdges(edges);

    for(edge e : G.edges) {
        int srcIndex = e->source()->index(), tgtIndex = e->target()->index();
        if (srcIndex <= tgtIndex) {
            minIndex[e] = srcIndex;
            maxIndex[e] = tgtIndex;
        } else {
            minIndex[e] = tgtIndex;
            maxIndex[e] = srcIndex;
        }
    }

    BucketEdgeArray bucketMin(minIndex), bucketMax(maxIndex);
    edges.bucketSort(0,G.maxNodeIndex(),bucketMin);
    edges.bucketSort(0,G.maxNodeIndex(),bucketMax);
}
// remove "arcs" from visibArcs which we already have in the constraint graph
// (as basic arcs)
void CompactionConstraintGraphBase::removeRedundantVisibArcs(
	SListPure<Tuple2<node,node> > &visibArcs)
{
	// bucket sort list of all edges
	SListPure<edge> all;
	allEdges(all);
	parallelFreeSort(*this,all);

	// bucket sort visibArcs
	BucketFirstIndex bucketSrc;
	visibArcs.bucketSort(0,maxNodeIndex(),bucketSrc);

	BucketSecondIndex bucketTgt;
	visibArcs.bucketSort(0,maxNodeIndex(),bucketTgt);

	// now, in both lists, arcs are sorted by increasing target index,
	// and arcs with the same target index by increasing source index.
	SListConstIterator<edge> itAll = all.begin();
	SListIterator<Tuple2<node,node> > it, itNext, itPrev;

	// for each arc in visibArcs, we check if it is also contained in list all
	for(it = visibArcs.begin(); it.valid(); it = itNext)
	{
		// required since we delete from the list we traverse
		itNext = it.succ();
		int i = (*it).x1()->index();
		int j = (*it).x2()->index();

		// skip all arcs with smaller target index
		while(itAll.valid() && (*itAll)->target()->index() < j)
			++itAll;

		// no more arcs => no more duplicates, so return
		if (!itAll.valid()) break;

		// if target index is j, we also skip all arcs with target index i
		// and source index smaller than i
		while(itAll.valid() && (*itAll)->target()->index() == j && (*itAll)->source()->index() < i)
			++itAll;

		// no more arcs => no more duplicates, so return
		if (!itAll.valid()) break;

		// if (i,j) is already present, we delete it from visibArcs
		if ((*itAll)->source()->index() == i &&
			(*itAll)->target()->index() == j)
		{
			//visibArcs.del(it);
			if (itPrev.valid())
				visibArcs.delSucc(itPrev);
			else
				visibArcs.popFront();
		} else
			itPrev = it;
	}//for visibArcs

	//****************************CHECK for
	//special treatment for cage visibility
	//two cases: input node cage: just compare arbitrary node
	//           merger cage: check first if there are mergers
	itPrev = nullptr;
	for(it = visibArcs.begin(); it.valid(); it = itNext)
	{

		itNext = it.succ();

		OGDF_ASSERT(!m_path[(*it).x1()].empty());
		OGDF_ASSERT(!m_path[(*it).x1()].empty());

		node boundRepresentant1 = m_path[(*it).x1()].front();
		node boundRepresentant2 = m_path[(*it).x2()].front();
		node en1 = m_pPR->expandedNode(boundRepresentant1);
		node en2 = m_pPR->expandedNode(boundRepresentant2);
		//do not allow visibility constraints in fixed cages
		//due to non-planarity with middle position constraints

		if ( ( en1 && en2 ) && ( en1 == en2) )
		{
			if (itPrev.valid()) visibArcs.delSucc(itPrev);
			else visibArcs.popFront();
		}
		else
		{
			//check if its a genmergerspanning vis arc, merge cases later
			node firstn = nullptr, secondn = nullptr;
			for (node n : m_path[(*it).x1()])
			{
				node en = m_pPR->expandedNode(n);
				if (!en) continue;
				if (!(m_pPR->typeOf(n) == Graph::generalizationExpander)) continue;
				else { firstn = en; break; }
			}//for
			for (node n : m_path[(*it).x2()])
			{
				node en = m_pPR->expandedNode(n);
				if (!en) continue;
				if (!(m_pPR->typeOf(n) == Graph::generalizationExpander)) continue;
				else { secondn = en; break; }
			}//for
			if ((firstn && secondn) && (firstn == secondn))
			{
				if (itPrev.valid()) visibArcs.delSucc(itPrev);
				else visibArcs.popFront();
			}
			else itPrev = it;
		}
	}//for visibArcs

}
示例#5
0
//---------------------------------------------------------
// actual call (called by all variations of call)
//   crossing of generalizations is forbidden if forbidCrossingGens = true
//   edge costs are obeyed if costOrig != 0
//
Module::ReturnType FixedEmbeddingInserter::doCall(
	PlanRep &PG,
	const List<edge> &origEdges,
	bool forbidCrossingGens,
	const EdgeArray<int>  *costOrig,
	const EdgeArray<bool> *forbiddenEdgeOrig,
	const EdgeArray<unsigned int> *edgeSubGraph)
{
  
	double T;
	usedTime(T);
	
	ReturnType retValue = retFeasible;
	m_runsPostprocessing = 0;

	PG.embed(); 
	OGDF_ASSERT(PG.representsCombEmbedding() == true);

	if (origEdges.size() == 0)
		return retOptimal;  // nothing to do

	// initialization
	CombinatorialEmbedding E(PG);  // embedding of PG

	m_dual.clear();
	m_primalAdj.init(m_dual);
	m_nodeOf.init(E);

	// construct dual graph
	m_primalIsGen.init(m_dual,false);

	OGDF_ASSERT(forbidCrossingGens == false || forbiddenEdgeOrig == 0);

	if(forbidCrossingGens)
		constructDualForbidCrossingGens((const PlanRepUML&)PG,E);
	else
		constructDual(PG,E,forbiddenEdgeOrig);

	// m_delFaces and m_newFaces are used by removeEdge()
	// if we can't allocate memory for them, we throw an exception
	if (removeReinsert() != rrNone) {
		m_delFaces = new FaceSetSimple(E);
		if (m_delFaces == 0)
			OGDF_THROW(InsufficientMemoryException);

		m_newFaces = new FaceSetPure(E);
		if (m_newFaces == 0) {
			delete m_delFaces;
			OGDF_THROW(InsufficientMemoryException);
		}

	// no postprocessing -> no removeEdge()
	} else {
		m_delFaces = 0;
		m_newFaces = 0;
	}

	SListPure<edge> currentOrigEdges;
	if(removeReinsert() == rrIncremental) {
		edge e;
		forall_edges(e,PG)
			currentOrigEdges.pushBack(PG.original(e));
	}

	// insertion of edges
	ListConstIterator<edge> it;
	for(it = origEdges.begin(); it.valid(); ++it)
	{
		edge eOrig = *it;

		int eSubGraph = 0;  // edgeSubGraph-data of eOrig
		if(edgeSubGraph!=0) eSubGraph = (*edgeSubGraph)[eOrig];

		SList<adjEntry> crossed;
		if(costOrig != 0) {
			findShortestPath(PG, E, *costOrig,
				PG.copy(eOrig->source()),PG.copy(eOrig->target()),
				forbidCrossingGens ? ((const PlanRepUML&)PG).typeOrig(eOrig) : Graph::association,
				crossed, edgeSubGraph, eSubGraph);
		} else {
			findShortestPath(E,
				PG.copy(eOrig->source()),PG.copy(eOrig->target()),
				forbidCrossingGens ? ((const PlanRepUML&)PG).typeOrig(eOrig) : Graph::association,
				crossed);
		}

		insertEdge(PG,E,eOrig,crossed,forbidCrossingGens,forbiddenEdgeOrig);
		
		if(removeReinsert() == rrIncremental) {
			currentOrigEdges.pushBack(eOrig);

			bool improved;
			do {
				++m_runsPostprocessing;
				improved = false;
				
				SListConstIterator<edge> itRR;
				for(itRR = currentOrigEdges.begin(); itRR.valid(); ++itRR)
				{
					edge eOrigRR = *itRR;
		
					int pathLength;
					if(costOrig != 0)
						pathLength = costCrossed(eOrigRR,PG,*costOrig,edgeSubGraph);
					else
						pathLength = PG.chain(eOrigRR).size() - 1;
					if (pathLength == 0) continue; // cannot improve
		
					removeEdge(PG,E,eOrigRR,forbidCrossingGens,forbiddenEdgeOrig);
		
					// try to find a better insertion path
					SList<adjEntry> crossed;
					if(costOrig != 0) {
						int eSubGraph = 0;  // edgeSubGraph-data of eOrig
						if(edgeSubGraph!=0) eSubGraph = (*edgeSubGraph)[eOrigRR];

						findShortestPath(PG, E, *costOrig,
							PG.copy(eOrigRR->source()),PG.copy(eOrigRR->target()),
							forbidCrossingGens ? ((const PlanRepUML&)PG).typeOrig(eOrigRR) : Graph::association,
							crossed, edgeSubGraph, eSubGraph);
					} else {
						findShortestPath(E,
							PG.copy(eOrigRR->source()),PG.copy(eOrigRR->target()),
							forbidCrossingGens ? ((const PlanRepUML&)PG).typeOrig(eOrigRR) : Graph::association,
							crossed);
					}
					
					// re-insert edge (insertion path cannot be longer)
					insertEdge(PG,E,eOrigRR,crossed,forbidCrossingGens,forbiddenEdgeOrig);
		
					int newPathLength = (costOrig != 0) ? costCrossed(eOrigRR,PG,*costOrig,edgeSubGraph) : (PG.chain(eOrigRR).size() - 1);
					OGDF_ASSERT(newPathLength <= pathLength);
					
					if(newPathLength < pathLength)
						improved = true;
				}
			} while (improved);
		}
	}

	const Graph &G = PG.original();
	if(removeReinsert() != rrIncremental) {
		// postprocessing (remove-reinsert heuristc)
		SListPure<edge> rrEdges;
	
		switch(removeReinsert())
		{
		case rrAll:
		case rrMostCrossed: {
				const List<node> &origInCC = PG.nodesInCC();
				ListConstIterator<node> itV;
	
				for(itV = origInCC.begin(); itV.valid(); ++itV) {
					node vG = *itV;
					adjEntry adj;
					forall_adj(adj,vG) {
						if ((adj->index() & 1) == 0) continue;
						edge eG = adj->theEdge();
						rrEdges.pushBack(eG);
					}
				}
			}
			break;
	
		case rrInserted:
			for(ListConstIterator<edge> it = origEdges.begin(); it.valid(); ++it)
				rrEdges.pushBack(*it);
			break;

		case rrNone:
		case rrIncremental:
			break;
		}
	
		// marks the end of the interval of rrEdges over which we iterate
		// initially set to invalid iterator which means all edges
		SListConstIterator<edge> itStop;
	
		bool improved;
		do {
			// abort postprocessing if time limit reached
			if (m_timeLimit >= 0 && m_timeLimit <= usedTime(T)) {
				retValue = retTimeoutFeasible;
				break;
			}
				
			++m_runsPostprocessing;
			improved = false;
	
			if(removeReinsert() == rrMostCrossed)
			{
				FEICrossingsBucket bucket(&PG);
				rrEdges.bucketSort(bucket);
	
				const int num = int(0.01 * percentMostCrossed() * G.numberOfEdges());
				itStop = rrEdges.get(num);
			}
	
			SListConstIterator<edge> it;
			for(it = rrEdges.begin(); it != itStop; ++it)
			{
				edge eOrig = *it;
							
				// remove only if crossings on edge;
				// in especially: forbidden edges are never handled by postprocessing
				//   since there are no crossings on such edges
				int pathLength;
				if(costOrig != 0)
					pathLength = costCrossed(eOrig,PG,*costOrig,edgeSubGraph);
				else
					pathLength = PG.chain(eOrig).size() - 1;
				if (pathLength == 0) continue; // cannot improve
	
				removeEdge(PG,E,eOrig,forbidCrossingGens,forbiddenEdgeOrig);
	
				// try to find a better insertion path
				SList<adjEntry> crossed;
				if(costOrig != 0) {
					int eSubGraph = 0;  // edgeSubGraph-data of eOrig
					if(edgeSubGraph!=0) eSubGraph = (*edgeSubGraph)[eOrig];

					findShortestPath(PG, E, *costOrig,
						PG.copy(eOrig->source()),PG.copy(eOrig->target()),
						forbidCrossingGens ? ((const PlanRepUML&)PG).typeOrig(eOrig) : Graph::association,
						crossed, edgeSubGraph, eSubGraph);
				} else {
					findShortestPath(E,
						PG.copy(eOrig->source()),PG.copy(eOrig->target()),
						forbidCrossingGens ? ((const PlanRepUML&)PG).typeOrig(eOrig) : Graph::association,
						crossed);
				}
	
				// re-insert edge (insertion path cannot be longer)
				insertEdge(PG,E,eOrig,crossed,forbidCrossingGens,forbiddenEdgeOrig);
	
				int newPathLength = (costOrig != 0) ? costCrossed(eOrig,PG,*costOrig,edgeSubGraph) : (PG.chain(eOrig).size() - 1);
				OGDF_ASSERT(newPathLength <= pathLength);
				
				if(newPathLength < pathLength)
					improved = true;
			}
		} while(improved); // iterate as long as we improve
	}
示例#6
0
	//--------------------------------------------------------------------
	// actual algorithm call
	//--------------------------------------------------------------------
	Module::ReturnType VarEdgeInserterDynCore::call(
		const Array<edge> &origEdges,
		RemoveReinsertType rrPost,
		double percentMostCrossed)
	{
		double T;
		usedTime(T);

		Module::ReturnType retValue = Module::retFeasible;
		m_runsPostprocessing = 0;

		if (origEdges.size() == 0)
			return Module::retOptimal;  // nothing to do

		SListPure<edge> currentOrigEdges;

		if (rrPost == rrIncremental) {
			for (edge e : m_pr.edges)
				currentOrigEdges.pushBack(m_pr.original(e));

			// insertion of edges
			for (int i = origEdges.low(); i <= origEdges.high(); ++i)
			{
				edge eOrig = origEdges[i];
				storeTypeOfCurrentEdge(eOrig);

				m_pBC = createBCandSPQRtrees();
				SList<adjEntry> eip;
				insert(eOrig, eip);
				m_pr.insertEdgePath(eOrig, eip);
				delete m_pBC;

				currentOrigEdges.pushBack(eOrig);

				bool improved;
				do {
					++m_runsPostprocessing;
					improved = false;

					for (edge eOrigRR : currentOrigEdges)
					{
						int pathLength = (m_pCost != nullptr) ? costCrossed(eOrigRR) : (m_pr.chain(eOrigRR).size() - 1);
						if (pathLength == 0) continue; // cannot improve

						m_pr.removeEdgePath(eOrigRR);

						storeTypeOfCurrentEdge(eOrigRR);

						m_pBC = createBCandSPQRtrees();
						SList<adjEntry> eip;
						insert(eOrigRR, eip);
						m_pr.insertEdgePath(eOrigRR, eip);
						delete m_pBC;

						int newPathLength = (m_pCost != nullptr) ? costCrossed(eOrigRR) : (m_pr.chain(eOrigRR).size() - 1);
						OGDF_ASSERT(newPathLength <= pathLength);

						if (newPathLength < pathLength)
							improved = true;
					}
				} while (improved);
			}

		}
		else {

			// insertion of edges
			m_pBC = createBCandSPQRtrees();

			for (int i = origEdges.low(); i <= origEdges.high(); ++i)
			{
				edge eOrig = origEdges[i];
				storeTypeOfCurrentEdge(eOrig);

				SList<adjEntry> eip;
				insert(eOrig, eip);
				m_pBC->insertEdgePath(eOrig, eip);
			}

			delete m_pBC;

			// postprocessing (remove-reinsert heuristc)
			const int m = m_pr.original().numberOfEdges();
			SListPure<edge> rrEdges;

			switch (rrPost)
			{
			case rrAll:
			case rrMostCrossed:
				for (int i = m_pr.startEdge(); i < m_pr.stopEdge(); ++i)
					rrEdges.pushBack(m_pr.e(i));
				break;

			case rrInserted:
				for (int i = origEdges.low(); i <= origEdges.high(); ++i)
					rrEdges.pushBack(origEdges[i]);
				break;

			case rrNone:
			case rrIncremental:
			case rrIncInserted:
				break;
			}

			// marks the end of the interval of rrEdges over which we iterate
			// initially set to invalid iterator which means all edges
			SListConstIterator<edge> itStop;

			bool improved;
			do {
				// abort postprocessing if time limit reached
				if (m_timeLimit >= 0 && m_timeLimit <= usedTime(T)) {
					retValue = Module::retTimeoutFeasible;
					break;
				}

				++m_runsPostprocessing;
				improved = false;

				if (rrPost == rrMostCrossed)
				{
					VEICrossingsBucket bucket(&m_pr);
					rrEdges.bucketSort(bucket);

					const int num = int(0.01 * percentMostCrossed * m);
					itStop = rrEdges.get(num);
				}

				SListConstIterator<edge> it;
				for (it = rrEdges.begin(); it != itStop; ++it)
				{
					edge eOrig = *it;

					int pathLength = (m_pCost != nullptr) ? costCrossed(eOrig) : (m_pr.chain(eOrig).size() - 1);
					if (pathLength == 0) continue; // cannot improve

					m_pr.removeEdgePath(eOrig);

					storeTypeOfCurrentEdge(eOrig);

					m_pBC = createBCandSPQRtrees();
					SList<adjEntry> eip;
					insert(eOrig, eip);
					m_pr.insertEdgePath(eOrig, eip);
					delete m_pBC;

					// we cannot find a shortest path that is longer than before!
					int newPathLength = (m_pCost != nullptr) ? costCrossed(eOrig) : (m_pr.chain(eOrig).size() - 1);
					OGDF_ASSERT(newPathLength <= pathLength);

					if (newPathLength < pathLength)
						improved = true;
				}

			} while (improved);
		}


#ifdef OGDF_DEBUG
		bool isPlanar =
#endif
			planarEmbed(m_pr);

		OGDF_ASSERT(isPlanar);

		m_pr.removePseudoCrossings();
		OGDF_ASSERT(m_pr.representsCombEmbedding());

		return retValue;
	}
示例#7
0
	//--------------------------------------------------------------------
	// actual algorithm call
	//--------------------------------------------------------------------
	Module::ReturnType FixEdgeInserterCore::call(
		const Array<edge> &origEdges,
		bool keepEmbedding,
		RemoveReinsertType rrPost,
		double percentMostCrossed)
	{
		double T;
		usedTime(T);

		Module::ReturnType retValue = Module::retFeasible;
		m_runsPostprocessing = 0;

		if(!keepEmbedding) m_pr.embed();
		OGDF_ASSERT(m_pr.representsCombEmbedding() == true);

		if (origEdges.size() == 0)
			return Module::retOptimal;  // nothing to do

		// initialization
		CombinatorialEmbedding E(m_pr);  // embedding of PG

		init(E);
		constructDual(E);

		// m_delFaces and m_newFaces are used by removeEdge()
		// if we can't allocate memory for them, we throw an exception
		if (rrPost != rrNone) {
			m_delFaces = new FaceSetSimple(E);
			if (m_delFaces == nullptr)
				OGDF_THROW(InsufficientMemoryException);

			m_newFaces = new FaceSetPure(E);
			if (m_newFaces == nullptr) {
				delete m_delFaces;
				OGDF_THROW(InsufficientMemoryException);
			}

		// no postprocessing -> no removeEdge()
		} else {
			m_delFaces = nullptr;
			m_newFaces = nullptr;
		}

		SListPure<edge> currentOrigEdges;
		if(rrPost == rrIncremental) {
			for(edge e : m_pr.edges)
				currentOrigEdges.pushBack(m_pr.original(e));
		}

		// insertion of edges
		bool doIncrementalPostprocessing =
			( rrPost == rrIncremental || rrPost == rrIncInserted );
		for(int i = origEdges.low(); i <= origEdges.high(); ++i)
		{
			edge eOrig = origEdges[i];
			storeTypeOfCurrentEdge(eOrig);
			//int eSubGraph = 0;  // edgeSubGraphs-data of eOrig
			//if(edgeSubGraphs!=0) eSubGraph = (*edgeSubGraphs)[eOrig];

			SList<adjEntry> crossed;
			if(m_pCost != nullptr) {
				findWeightedShortestPath(E, eOrig, crossed);
			} else {
				findShortestPath(E, eOrig, crossed);
			}

			insertEdge(E, eOrig, crossed);

			if(doIncrementalPostprocessing) {
				currentOrigEdges.pushBack(eOrig);

				bool improved;
				do {
					++m_runsPostprocessing;
					improved = false;

					for (edge eOrigRR : currentOrigEdges)
					{
						int pathLength = (m_pCost != nullptr) ? costCrossed(eOrigRR) : (m_pr.chain(eOrigRR).size() - 1);
						if (pathLength == 0) continue; // cannot improve

						removeEdge(E, eOrigRR);

						storeTypeOfCurrentEdge(eOrigRR);

						// try to find a better insertion path
						SList<adjEntry> crossed;
						if(m_pCost != nullptr) {
							findWeightedShortestPath(E, eOrigRR, crossed);
						} else {
							findShortestPath(E, eOrigRR, crossed);
						}

						// re-insert edge (insertion path cannot be longer)
						insertEdge(E, eOrigRR, crossed);

						int newPathLength = (m_pCost != nullptr) ? costCrossed(eOrigRR) : (m_pr.chain(eOrigRR).size() - 1);
						OGDF_ASSERT(newPathLength <= pathLength);

						if(newPathLength < pathLength)
							improved = true;
					}
				} while (improved);
			}
		}

		if(!doIncrementalPostprocessing) {
			// postprocessing (remove-reinsert heuristc)
			const int m = m_pr.original().numberOfEdges();
			SListPure<edge> rrEdges;

			switch(rrPost)
			{
			case rrAll:
			case rrMostCrossed:
				for(int i = m_pr.startEdge(); i < m_pr.stopEdge(); ++i)
					rrEdges.pushBack(m_pr.e(i));
				break;

			case rrInserted:
				for(int i = origEdges.low(); i <= origEdges.high(); ++i)
					rrEdges.pushBack(origEdges[i]);
				break;

			case rrNone:
			case rrIncremental:
			case rrIncInserted:
				break;
			}

			// marks the end of the interval of rrEdges over which we iterate
			// initially set to invalid iterator which means all edges
			SListConstIterator<edge> itStop;

			bool improved;
			do {
				// abort postprocessing if time limit reached
				if (m_timeLimit >= 0 && m_timeLimit <= usedTime(T)) {
					retValue = Module::retTimeoutFeasible;
					break;
				}

				++m_runsPostprocessing;
				improved = false;

				if(rrPost == rrMostCrossed)
				{
					FEICrossingsBucket bucket(&m_pr);
					rrEdges.bucketSort(bucket);

					const int num = int(0.01 * percentMostCrossed * m);
					itStop = rrEdges.get(num);
				}

				SListConstIterator<edge> it;
				for(it = rrEdges.begin(); it != itStop; ++it)
				{
					edge eOrig = *it;

					int pathLength = (m_pCost != nullptr) ? costCrossed(eOrig) : (m_pr.chain(eOrig).size() - 1);
					if (pathLength == 0) continue; // cannot improve

					removeEdge(E, eOrig);

					storeTypeOfCurrentEdge(eOrig);

					// try to find a better insertion path
					SList<adjEntry> crossed;
					if(m_pCost != nullptr) {
						findWeightedShortestPath(E, eOrig, crossed);
					} else {
						findShortestPath(E, eOrig, crossed);
					}

					// re-insert edge (insertion path cannot be longer)
					insertEdge(E, eOrig, crossed);

					// we cannot find a shortest path that is longer than before!
					int newPathLength = (m_pCost != nullptr) ? costCrossed(eOrig) : (m_pr.chain(eOrig).size() - 1);
					OGDF_ASSERT(newPathLength <= pathLength);

					if(newPathLength < pathLength)
						improved = true;
				}
			} while (improved);
		}

		// verify computed planarization
		OGDF_ASSERT(m_pr.representsCombEmbedding());

		// free resources
		cleanup();

		return retValue;
	}