# HG changeset patch
# User marci
# Date 1083260082 0
# Node ID 7f461ab4af1a22a95981f30c1252641713c35cf9
# Parent  13e57edac8ed56187ca9a5e00ff805344bfd4419
Some docu in MaxFlow class, jacint/max_flow.h

diff -r 13e57edac8ed -r 7f461ab4af1a src/work/jacint/max_flow.h
--- a/src/work/jacint/max_flow.h	Thu Apr 29 17:23:56 2004 +0000
+++ b/src/work/jacint/max_flow.h	Thu Apr 29 17:34:42 2004 +0000
@@ -1,35 +1,35 @@
 // -*- C++ -*-
 
 /*
-Heuristics: 
- 2 phase
- gap
- list 'level_list' on the nodes on level i implemented by hand
- stack 'active' on the active nodes on level i
- runs heuristic 'highest label' for H1*n relabels
- runs heuristic 'bound decrease' for H0*n relabels, starts with 'highest label'
+  Heuristics: 
+  2 phase
+  gap
+  list 'level_list' on the nodes on level i implemented by hand
+  stack 'active' on the active nodes on level i
+  runs heuristic 'highest label' for H1*n relabels
+  runs heuristic 'bound decrease' for H0*n relabels, starts with 'highest label'
  
-Parameters H0 and H1 are initialized to 20 and 1.
+  Parameters H0 and H1 are initialized to 20 and 1.
 
-Constructors:
+  Constructors:
 
-Preflow(Graph, Node, Node, CapMap, FlowMap, bool) : bool must be false if 
-     FlowMap is not constant zero, and should be true if it is
+  Preflow(Graph, Node, Node, CapMap, FlowMap, bool) : bool must be false if 
+  FlowMap is not constant zero, and should be true if it is
 
-Members:
+  Members:
 
-void run()
+  void run()
 
-Num flowValue() : returns the value of a maximum flow
+  Num flowValue() : returns the value of a maximum flow
 
-void minMinCut(CutMap& M) : sets M to the characteristic vector of the 
-     minimum min cut. M should be a map of bools initialized to false. ??Is it OK?
+  void minMinCut(CutMap& M) : sets M to the characteristic vector of the 
+  minimum min cut. M should be a map of bools initialized to false. ??Is it OK?
 
-void maxMinCut(CutMap& M) : sets M to the characteristic vector of the 
-     maximum min cut. M should be a map of bools initialized to false.
+  void maxMinCut(CutMap& M) : sets M to the characteristic vector of the 
+  maximum min cut. M should be a map of bools initialized to false.
 
-void minCut(CutMap& M) : sets M to the characteristic vector of 
-     a min cut. M should be a map of bools initialized to false.
+  void minCut(CutMap& M) : sets M to the characteristic vector of 
+  a min cut. M should be a map of bools initialized to false.
 
 */
 
@@ -52,6 +52,7 @@
 
 namespace hugo {
 
+  ///\author Marton Makai, Jacint Szabo
   template <typename Graph, typename Num, 
 	    typename CapMap=typename Graph::template EdgeMap<Num>, 
             typename FlowMap=typename Graph::template EdgeMap<Num> >
@@ -97,23 +98,39 @@
       g(&_G), s(_s), t(_t), capacity(&_capacity), 
       flow(&_flow), n(_G.nodeNum()), level(_G), excess(_G,0) {}
 
+    /// A max flow algorithm is run.
+    ///\pre the flow have to be 0 at the beginning.
     void run() {
       preflow( ZERO_FLOW );
     }
     
+    /// A preflow algorithm is run. The initial edge-set have to be a flow, 
+    /// or from a preflow, according to \c fe.
     void preflow( flowEnum fe ) {
       preflowPhase0(fe);
       preflowPhase1();
     }
 
+    /// Run the first phase of preflow, starting from a 0 flow, from a flow, 
+    /// or from a preflow, according to \c fe.
     void preflowPhase0( flowEnum fe );
 
+    /// Second phase of preflow.
     void preflowPhase1();
 
+    /// Starting from a flow, this method searches for an augmenting path 
+    /// according to the Edmonds-Karp algorithm 
+    /// and augments the flow on if any. 
     bool augmentOnShortestPath();
 
+    /// Starting from a flow, this method searches for an augmenting blockin 
+    /// flow according to Dinits' algorithm and augments the flow on if any. 
+    /// The blocking flow is computed in a physically constructed 
+    /// residual graph of type \c Mutablegraph.
     template<typename MutableGraph> bool augmentOnBlockingFlow();
 
+    /// The same as \c augmentOnBlockingFlow<MutableGraph> but the 
+    /// residual graph is not constructed physically.
     bool augmentOnBlockingFlow2();
 
     /// Returns the actual flow value.
@@ -126,23 +143,26 @@
       return a;
     }
 
-    //should be used only between preflowPhase0 and preflowPhase1
+    /// Should be used between preflowPhase0 and preflowPhase1.
+    ///\todo We have to make some status variable which shows the actual state 
+    /// of the class. This enables us to determine which methods are valid 
+    /// for MinCut computation
     template<typename _CutMap>
     void actMinCut(_CutMap& M) {
       NodeIt v;
-      for(g->first(v); g->valid(v); g->next(v)) 
-      if ( level[v] < n ) {
-	M.set(v,false);
-      } else {
-	M.set(v,true);
+      for(g->first(v); g->valid(v); g->next(v)) {
+	if ( level[v] < n ) {
+	  M.set(v,false);
+	} else {
+	  M.set(v,true);
+	}
       }
     }
 
 
-
-    /*
-      Returns the minimum min cut, by a bfs from s in the residual graph.
-    */
+    /// The unique inclusionwise minimum cut is computed by 
+    /// processing a bfs from s in the residual graph.
+    ///\pre flow have to be a max flow otherwise it will the whole node-set.
     template<typename _CutMap>
     void minMinCut(_CutMap& M) {
     
@@ -176,12 +196,9 @@
     }
 
 
-  
-    /*
-      Returns the maximum min cut, by a reverse bfs 
-      from t in the residual graph.
-    */
-    
+    /// The unique inclusionwise maximum cut is computed by 
+    /// processing a reverse bfs from t in the residual graph.
+    ///\pre flow have to be a max flow otherwise it will be empty.
     template<typename _CutMap>
     void maxMinCut(_CutMap& M) {
 
@@ -221,21 +238,20 @@
     }
 
 
+    /// A minimum cut is computed.
     template<typename CutMap>
-    void minCut(CutMap& M) {
-      minMinCut(M);
-    }
+    void minCut(CutMap& M) { minMinCut(M); }
 
+    /// 
+    void resetSource(Node _s) {s=_s;}
+    ///
     void resetTarget(Node _t) {t=_t;}
-    void resetSource(Node _s) {s=_s;}
    
-    void resetCap(const CapMap& _cap) {
-      capacity=&_cap;
-    }
+    /// capacity-map is changed.
+    void resetCap(const CapMap& _cap) { capacity=&_cap; }
     
-    void resetFlow(FlowMap& _flow) {
-      flow=&_flow;
-    }
+    /// flow-map is changed. 
+    void resetFlow(FlowMap& _flow) { flow=&_flow; }
 
 
   private:
@@ -314,130 +330,130 @@
       excess.set(w, exc);
       
       return newlevel;
-     }
+    }
 
 
     void preflowPreproc ( flowEnum fe, VecStack& active, 
 			  VecNode& level_list, NNMap& left, NNMap& right ) {
 
-      std::queue<Node> bfs_queue;
+			    std::queue<Node> bfs_queue;
       
-      switch ( fe ) {
-      case ZERO_FLOW: 
-	{
-	  //Reverse_bfs from t, to find the starting level.
-	  level.set(t,0);
-	  bfs_queue.push(t);
+			    switch ( fe ) {
+			    case ZERO_FLOW: 
+			      {
+				//Reverse_bfs from t, to find the starting level.
+				level.set(t,0);
+				bfs_queue.push(t);
 	
-	  while (!bfs_queue.empty()) {
+				while (!bfs_queue.empty()) {
 	    
-	    Node v=bfs_queue.front();	
-	    bfs_queue.pop();
-	    int l=level[v]+1;
+				  Node v=bfs_queue.front();	
+				  bfs_queue.pop();
+				  int l=level[v]+1;
 	    
-	    InEdgeIt e;
-	    for(g->first(e,v); g->valid(e); g->next(e)) {
-	      Node w=g->tail(e);
-	      if ( level[w] == n && w != s ) {
-		bfs_queue.push(w);
-		Node first=level_list[l];
-		if ( g->valid(first) ) left.set(first,w);
-		right.set(w,first);
-		level_list[l]=w;
-		level.set(w, l);
-	      }
-	    }
-	  }
+				  InEdgeIt e;
+				  for(g->first(e,v); g->valid(e); g->next(e)) {
+				    Node w=g->tail(e);
+				    if ( level[w] == n && w != s ) {
+				      bfs_queue.push(w);
+				      Node first=level_list[l];
+				      if ( g->valid(first) ) left.set(first,w);
+				      right.set(w,first);
+				      level_list[l]=w;
+				      level.set(w, l);
+				    }
+				  }
+				}
 	  
-	  //the starting flow
-	  OutEdgeIt e;
-	  for(g->first(e,s); g->valid(e); g->next(e)) 
-	    {
-	      Num c=(*capacity)[e];
-	      if ( c <= 0 ) continue;
-	      Node w=g->head(e);
-	      if ( level[w] < n ) {	  
-		if ( excess[w] <= 0 && w!=t ) active[level[w]].push(w);
-		flow->set(e, c); 
-		excess.set(w, excess[w]+c);
-	      }
-	    }
-	  break;
-	}
+				//the starting flow
+				OutEdgeIt e;
+				for(g->first(e,s); g->valid(e); g->next(e)) 
+				  {
+				    Num c=(*capacity)[e];
+				    if ( c <= 0 ) continue;
+				    Node w=g->head(e);
+				    if ( level[w] < n ) {	  
+				      if ( excess[w] <= 0 && w!=t ) active[level[w]].push(w);
+				      flow->set(e, c); 
+				      excess.set(w, excess[w]+c);
+				    }
+				  }
+				break;
+			      }
 	
-      case GEN_FLOW:
-      case PREFLOW:
-	{
-	  //Reverse_bfs from t in the residual graph, 
-	  //to find the starting level.
-	  level.set(t,0);
-	  bfs_queue.push(t);
+			    case GEN_FLOW:
+			    case PREFLOW:
+			      {
+				//Reverse_bfs from t in the residual graph, 
+				//to find the starting level.
+				level.set(t,0);
+				bfs_queue.push(t);
 	  
-	  while (!bfs_queue.empty()) {
+				while (!bfs_queue.empty()) {
 	    
-	    Node v=bfs_queue.front();	
-	    bfs_queue.pop();
-	    int l=level[v]+1;
+				  Node v=bfs_queue.front();	
+				  bfs_queue.pop();
+				  int l=level[v]+1;
 	    
-	    InEdgeIt e;
-	    for(g->first(e,v); g->valid(e); g->next(e)) {
-	      if ( (*capacity)[e] <= (*flow)[e] ) continue;
-	      Node w=g->tail(e);
-	      if ( level[w] == n && w != s ) {
-		bfs_queue.push(w);
-		Node first=level_list[l];
-		if ( g->valid(first) ) left.set(first,w);
-		right.set(w,first);
-		level_list[l]=w;
-		level.set(w, l);
-	      }
-	    }
+				  InEdgeIt e;
+				  for(g->first(e,v); g->valid(e); g->next(e)) {
+				    if ( (*capacity)[e] <= (*flow)[e] ) continue;
+				    Node w=g->tail(e);
+				    if ( level[w] == n && w != s ) {
+				      bfs_queue.push(w);
+				      Node first=level_list[l];
+				      if ( g->valid(first) ) left.set(first,w);
+				      right.set(w,first);
+				      level_list[l]=w;
+				      level.set(w, l);
+				    }
+				  }
 	    
-	    OutEdgeIt f;
-	    for(g->first(f,v); g->valid(f); g->next(f)) {
-	      if ( 0 >= (*flow)[f] ) continue;
-	      Node w=g->head(f);
-	      if ( level[w] == n && w != s ) {
-		bfs_queue.push(w);
-		Node first=level_list[l];
-		if ( g->valid(first) ) left.set(first,w);
-		right.set(w,first);
-		level_list[l]=w;
-		level.set(w, l);
-	      }
-	    }
-	  }
+				  OutEdgeIt f;
+				  for(g->first(f,v); g->valid(f); g->next(f)) {
+				    if ( 0 >= (*flow)[f] ) continue;
+				    Node w=g->head(f);
+				    if ( level[w] == n && w != s ) {
+				      bfs_queue.push(w);
+				      Node first=level_list[l];
+				      if ( g->valid(first) ) left.set(first,w);
+				      right.set(w,first);
+				      level_list[l]=w;
+				      level.set(w, l);
+				    }
+				  }
+				}
 	  
 	  
-	  //the starting flow
-	  OutEdgeIt e;
-	  for(g->first(e,s); g->valid(e); g->next(e)) 
-	    {
-	      Num rem=(*capacity)[e]-(*flow)[e];
-	      if ( rem <= 0 ) continue;
-	      Node w=g->head(e);
-	      if ( level[w] < n ) {	  
-		if ( excess[w] <= 0 && w!=t ) active[level[w]].push(w);
-		flow->set(e, (*capacity)[e]); 
-		excess.set(w, excess[w]+rem);
-	      }
-	    }
+				//the starting flow
+				OutEdgeIt e;
+				for(g->first(e,s); g->valid(e); g->next(e)) 
+				  {
+				    Num rem=(*capacity)[e]-(*flow)[e];
+				    if ( rem <= 0 ) continue;
+				    Node w=g->head(e);
+				    if ( level[w] < n ) {	  
+				      if ( excess[w] <= 0 && w!=t ) active[level[w]].push(w);
+				      flow->set(e, (*capacity)[e]); 
+				      excess.set(w, excess[w]+rem);
+				    }
+				  }
 	  
-	  InEdgeIt f;
-	  for(g->first(f,s); g->valid(f); g->next(f)) 
-	    {
-	      if ( (*flow)[f] <= 0 ) continue;
-	      Node w=g->tail(f);
-	      if ( level[w] < n ) {	  
-		if ( excess[w] <= 0 && w!=t ) active[level[w]].push(w);
-		excess.set(w, excess[w]+(*flow)[f]);
-		flow->set(f, 0); 
-	      }
-	    }  
-	  break;
-	} //case PREFLOW
-      }
-    } //preflowPreproc
+				InEdgeIt f;
+				for(g->first(f,s); g->valid(f); g->next(f)) 
+				  {
+				    if ( (*flow)[f] <= 0 ) continue;
+				    Node w=g->tail(f);
+				    if ( level[w] < n ) {	  
+				      if ( excess[w] <= 0 && w!=t ) active[level[w]].push(w);
+				      excess.set(w, excess[w]+(*flow)[f]);
+				      flow->set(f, 0); 
+				    }
+				  }  
+				break;
+			      } //case PREFLOW
+			    }
+			  } //preflowPreproc
 
 
 
@@ -521,11 +537,11 @@
 	dist.set(n, a); 
       }
       int operator[](const typename MapGraphWrapper::Node& n) 
-	{ return dist[n]; }
-//       int get(const typename MapGraphWrapper::Node& n) const { 
-// 	return dist[n]; }
-//       bool get(const typename MapGraphWrapper::Edge& e) const { 
-// 	return (dist.get(g->tail(e))<dist.get(g->head(e))); }
+      { return dist[n]; }
+      //       int get(const typename MapGraphWrapper::Node& n) const { 
+      // 	return dist[n]; }
+      //       bool get(const typename MapGraphWrapper::Edge& e) const { 
+      // 	return (dist.get(g->tail(e))<dist.get(g->head(e))); }
       bool operator[](const typename MapGraphWrapper::Edge& e) const { 
 	return (dist[g->tail(e)]<dist[g->head(e)]); 
       }
@@ -538,108 +554,108 @@
   void MaxFlow<Graph, Num, CapMap, FlowMap>::preflowPhase0( flowEnum fe ) 
   {
       
-      int heur0=(int)(H0*n);  //time while running 'bound decrease' 
-      int heur1=(int)(H1*n);  //time while running 'highest label'
-      int heur=heur1;         //starting time interval (#of relabels)
-      int numrelabel=0;
+    int heur0=(int)(H0*n);  //time while running 'bound decrease' 
+    int heur1=(int)(H1*n);  //time while running 'highest label'
+    int heur=heur1;         //starting time interval (#of relabels)
+    int numrelabel=0;
      
-      bool what_heur=1;       
-      //It is 0 in case 'bound decrease' and 1 in case 'highest label'
+    bool what_heur=1;       
+    //It is 0 in case 'bound decrease' and 1 in case 'highest label'
 
-      bool end=false;     
-      //Needed for 'bound decrease', true means no active nodes are above bound b.
+    bool end=false;     
+    //Needed for 'bound decrease', true means no active nodes are above bound b.
 
-      int k=n-2;  //bound on the highest level under n containing a node
-      int b=k;    //bound on the highest level under n of an active node
+    int k=n-2;  //bound on the highest level under n containing a node
+    int b=k;    //bound on the highest level under n of an active node
       
-      VecStack active(n);
+    VecStack active(n);
       
-      NNMap left(*g, INVALID);
-      NNMap right(*g, INVALID);
-      VecNode level_list(n,INVALID);
-      //List of the nodes in level i<n, set to n.
+    NNMap left(*g, INVALID);
+    NNMap right(*g, INVALID);
+    VecNode level_list(n,INVALID);
+    //List of the nodes in level i<n, set to n.
 
-      NodeIt v;
-      for(g->first(v); g->valid(v); g->next(v)) level.set(v,n);
-      //setting each node to level n
+    NodeIt v;
+    for(g->first(v); g->valid(v); g->next(v)) level.set(v,n);
+    //setting each node to level n
       
-      switch ( fe ) {
-      case PREFLOW:
-	{
-	  //counting the excess
-	  NodeIt v;
-	  for(g->first(v); g->valid(v); g->next(v)) {
-	    Num exc=0;
-	  
-	    InEdgeIt e;
-	    for(g->first(e,v); g->valid(e); g->next(e)) exc+=(*flow)[e];
-	    OutEdgeIt f;
-	    for(g->first(f,v); g->valid(f); g->next(f)) exc-=(*flow)[f];
-	    
-	    excess.set(v,exc);	  
-	    
-	    //putting the active nodes into the stack
-	    int lev=level[v];
-	    if ( exc > 0 && lev < n && v != t ) active[lev].push(v);
-	  }
-	  break;
-	}
-      case GEN_FLOW:
-	{
-	  //Counting the excess of t
+    switch ( fe ) {
+    case PREFLOW:
+      {
+	//counting the excess
+	NodeIt v;
+	for(g->first(v); g->valid(v); g->next(v)) {
 	  Num exc=0;
 	  
 	  InEdgeIt e;
-	  for(g->first(e,t); g->valid(e); g->next(e)) exc+=(*flow)[e];
+	  for(g->first(e,v); g->valid(e); g->next(e)) exc+=(*flow)[e];
 	  OutEdgeIt f;
-	  for(g->first(f,t); g->valid(f); g->next(f)) exc-=(*flow)[f];
-	  
-	  excess.set(t,exc);	
-	  
-	  break;
+	  for(g->first(f,v); g->valid(f); g->next(f)) exc-=(*flow)[f];
+	    
+	  excess.set(v,exc);	  
+	    
+	  //putting the active nodes into the stack
+	  int lev=level[v];
+	  if ( exc > 0 && lev < n && v != t ) active[lev].push(v);
 	}
-      default:
 	break;
       }
+    case GEN_FLOW:
+      {
+	//Counting the excess of t
+	Num exc=0;
+	  
+	InEdgeIt e;
+	for(g->first(e,t); g->valid(e); g->next(e)) exc+=(*flow)[e];
+	OutEdgeIt f;
+	for(g->first(f,t); g->valid(f); g->next(f)) exc-=(*flow)[f];
+	  
+	excess.set(t,exc);	
+	  
+	break;
+      }
+    default:
+      break;
+    }
       
-      preflowPreproc( fe, active, level_list, left, right );
-      //End of preprocessing 
+    preflowPreproc( fe, active, level_list, left, right );
+    //End of preprocessing 
       
       
-      //Push/relabel on the highest level active nodes.
-      while ( true ) {
-	if ( b == 0 ) {
-	  if ( !what_heur && !end && k > 0 ) {
-	    b=k;
-	    end=true;
-	  } else break;
+    //Push/relabel on the highest level active nodes.
+    while ( true ) {
+      if ( b == 0 ) {
+	if ( !what_heur && !end && k > 0 ) {
+	  b=k;
+	  end=true;
+	} else break;
+      }
+	
+      if ( active[b].empty() ) --b; 
+      else {
+	end=false;  
+	Node w=active[b].top();
+	active[b].pop();
+	int newlevel=push(w,active);
+	if ( excess[w] > 0 ) relabel(w, newlevel, active, level_list, 
+				     left, right, b, k, what_heur);
+	  
+	++numrelabel; 
+	if ( numrelabel >= heur ) {
+	  numrelabel=0;
+	  if ( what_heur ) {
+	    what_heur=0;
+	    heur=heur0;
+	    end=false;
+	  } else {
+	    what_heur=1;
+	    heur=heur1;
+	    b=k; 
+	  }
 	}
-	
-	if ( active[b].empty() ) --b; 
-	else {
-	  end=false;  
-	  Node w=active[b].top();
-	  active[b].pop();
-	  int newlevel=push(w,active);
-	  if ( excess[w] > 0 ) relabel(w, newlevel, active, level_list, 
-				       left, right, b, k, what_heur);
-	  
-	  ++numrelabel; 
-	  if ( numrelabel >= heur ) {
-	    numrelabel=0;
-	    if ( what_heur ) {
-	      what_heur=0;
-	      heur=heur0;
-	      end=false;
-	    } else {
-	      what_heur=1;
-	      heur=heur1;
-	      b=k; 
-	    }
-	  }
-	} 
       } 
-    }
+    } 
+  }
 
 
 
@@ -647,112 +663,112 @@
   void MaxFlow<Graph, Num, CapMap, FlowMap>::preflowPhase1() 
   {
       
-      int k=n-2;  //bound on the highest level under n containing a node
-      int b=k;    //bound on the highest level under n of an active node
+    int k=n-2;  //bound on the highest level under n containing a node
+    int b=k;    //bound on the highest level under n of an active node
       
-      VecStack active(n);
-      level.set(s,0);
-      std::queue<Node> bfs_queue;
-      bfs_queue.push(s);
+    VecStack active(n);
+    level.set(s,0);
+    std::queue<Node> bfs_queue;
+    bfs_queue.push(s);
 	    
-      while (!bfs_queue.empty()) {
+    while (!bfs_queue.empty()) {
 	
-	Node v=bfs_queue.front();	
-	bfs_queue.pop();
-	int l=level[v]+1;
+      Node v=bfs_queue.front();	
+      bfs_queue.pop();
+      int l=level[v]+1;
 	      
-	InEdgeIt e;
-	for(g->first(e,v); g->valid(e); g->next(e)) {
-	  if ( (*capacity)[e] <= (*flow)[e] ) continue;
-	  Node u=g->tail(e);
-	  if ( level[u] >= n ) { 
-	    bfs_queue.push(u);
-	    level.set(u, l);
-	    if ( excess[u] > 0 ) active[l].push(u);
-	  }
-	}
-	
-	OutEdgeIt f;
-	for(g->first(f,v); g->valid(f); g->next(f)) {
-	  if ( 0 >= (*flow)[f] ) continue;
-	  Node u=g->head(f);
-	  if ( level[u] >= n ) { 
-	    bfs_queue.push(u);
-	    level.set(u, l);
-	    if ( excess[u] > 0 ) active[l].push(u);
-	  }
+      InEdgeIt e;
+      for(g->first(e,v); g->valid(e); g->next(e)) {
+	if ( (*capacity)[e] <= (*flow)[e] ) continue;
+	Node u=g->tail(e);
+	if ( level[u] >= n ) { 
+	  bfs_queue.push(u);
+	  level.set(u, l);
+	  if ( excess[u] > 0 ) active[l].push(u);
 	}
       }
-      b=n-2;
+	
+      OutEdgeIt f;
+      for(g->first(f,v); g->valid(f); g->next(f)) {
+	if ( 0 >= (*flow)[f] ) continue;
+	Node u=g->head(f);
+	if ( level[u] >= n ) { 
+	  bfs_queue.push(u);
+	  level.set(u, l);
+	  if ( excess[u] > 0 ) active[l].push(u);
+	}
+      }
+    }
+    b=n-2;
 
-      while ( true ) {
+    while ( true ) {
 	
-	if ( b == 0 ) break;
+      if ( b == 0 ) break;
 
-	if ( active[b].empty() ) --b; 
-	else {
-	  Node w=active[b].top();
-	  active[b].pop();
-	  int newlevel=push(w,active);	  
+      if ( active[b].empty() ) --b; 
+      else {
+	Node w=active[b].top();
+	active[b].pop();
+	int newlevel=push(w,active);	  
 
-	  //relabel
-	  if ( excess[w] > 0 ) {
-	    level.set(w,++newlevel);
-	    active[newlevel].push(w);
-	    b=newlevel;
-	  }
-	}  // if stack[b] is nonempty
-      } // while(true)
-    }
+	//relabel
+	if ( excess[w] > 0 ) {
+	  level.set(w,++newlevel);
+	  active[newlevel].push(w);
+	  b=newlevel;
+	}
+      }  // if stack[b] is nonempty
+    } // while(true)
+  }
 
 
 
   template <typename Graph, typename Num, typename CapMap, typename FlowMap>
   bool MaxFlow<Graph, Num, CapMap, FlowMap>::augmentOnShortestPath() 
   {
-      ResGW res_graph(*g, *capacity, *flow);
-      bool _augment=false;
+    ResGW res_graph(*g, *capacity, *flow);
+    bool _augment=false;
       
-      //ReachedMap level(res_graph);
-      FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);
-      BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);
-      bfs.pushAndSetReached(s);
+    //ReachedMap level(res_graph);
+    FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);
+    BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);
+    bfs.pushAndSetReached(s);
 	
-      typename ResGW::template NodeMap<ResGWEdge> pred(res_graph); 
-      pred.set(s, INVALID);
+    typename ResGW::template NodeMap<ResGWEdge> pred(res_graph); 
+    pred.set(s, INVALID);
       
-      typename ResGW::template NodeMap<Num> free(res_graph);
+    typename ResGW::template NodeMap<Num> free(res_graph);
 	
-      //searching for augmenting path
-      while ( !bfs.finished() ) { 
-	ResGWOutEdgeIt e=bfs;
-	if (res_graph.valid(e) && bfs.isBNodeNewlyReached()) {
-	  Node v=res_graph.tail(e);
-	  Node w=res_graph.head(e);
-	  pred.set(w, e);
-	  if (res_graph.valid(pred[v])) {
-	    free.set(w, std::min(free[v], res_graph.resCap(e)));
-	  } else {
-	    free.set(w, res_graph.resCap(e)); 
-	  }
-	  if (res_graph.head(e)==t) { _augment=true; break; }
+    //searching for augmenting path
+    while ( !bfs.finished() ) { 
+      ResGWOutEdgeIt e=bfs;
+      if (res_graph.valid(e) && bfs.isBNodeNewlyReached()) {
+	Node v=res_graph.tail(e);
+	Node w=res_graph.head(e);
+	pred.set(w, e);
+	if (res_graph.valid(pred[v])) {
+	  free.set(w, std::min(free[v], res_graph.resCap(e)));
+	} else {
+	  free.set(w, res_graph.resCap(e)); 
 	}
+	if (res_graph.head(e)==t) { _augment=true; break; }
+      }
 	
-	++bfs;
-      } //end of searching augmenting path
+      ++bfs;
+    } //end of searching augmenting path
 
-      if (_augment) {
-	Node n=t;
-	Num augment_value=free[t];
-	while (res_graph.valid(pred[n])) { 
-	  ResGWEdge e=pred[n];
-	  res_graph.augment(e, augment_value); 
-	  n=res_graph.tail(e);
-	}
+    if (_augment) {
+      Node n=t;
+      Num augment_value=free[t];
+      while (res_graph.valid(pred[n])) { 
+	ResGWEdge e=pred[n];
+	res_graph.augment(e, augment_value); 
+	n=res_graph.tail(e);
       }
+    }
 
-      return _augment;
-    }
+    return _augment;
+  }
 
 
 
@@ -766,114 +782,114 @@
   template<typename MutableGraph> 
   bool MaxFlow<Graph, Num, CapMap, FlowMap>::augmentOnBlockingFlow() 
   {      
-      typedef MutableGraph MG;
-      bool _augment=false;
+    typedef MutableGraph MG;
+    bool _augment=false;
 
-      ResGW res_graph(*g, *capacity, *flow);
+    ResGW res_graph(*g, *capacity, *flow);
 
-      //bfs for distances on the residual graph
-      //ReachedMap level(res_graph);
-      FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);
-      BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);
-      bfs.pushAndSetReached(s);
-      typename ResGW::template NodeMap<int> 
-	dist(res_graph); //filled up with 0's
+    //bfs for distances on the residual graph
+    //ReachedMap level(res_graph);
+    FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);
+    BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);
+    bfs.pushAndSetReached(s);
+    typename ResGW::template NodeMap<int> 
+      dist(res_graph); //filled up with 0's
 
-      //F will contain the physical copy of the residual graph
-      //with the set of edges which are on shortest paths
-      MG F;
-      typename ResGW::template NodeMap<typename MG::Node> 
-	res_graph_to_F(res_graph);
-      {
-	typename ResGW::NodeIt n;
-	for(res_graph.first(n); res_graph.valid(n); res_graph.next(n)) {
-	  res_graph_to_F.set(n, F.addNode());
-	}
+    //F will contain the physical copy of the residual graph
+    //with the set of edges which are on shortest paths
+    MG F;
+    typename ResGW::template NodeMap<typename MG::Node> 
+      res_graph_to_F(res_graph);
+    {
+      typename ResGW::NodeIt n;
+      for(res_graph.first(n); res_graph.valid(n); res_graph.next(n)) {
+	res_graph_to_F.set(n, F.addNode());
       }
+    }
 
-      typename MG::Node sF=res_graph_to_F[s];
-      typename MG::Node tF=res_graph_to_F[t];
-      typename MG::template EdgeMap<ResGWEdge> original_edge(F);
-      typename MG::template EdgeMap<Num> residual_capacity(F);
+    typename MG::Node sF=res_graph_to_F[s];
+    typename MG::Node tF=res_graph_to_F[t];
+    typename MG::template EdgeMap<ResGWEdge> original_edge(F);
+    typename MG::template EdgeMap<Num> residual_capacity(F);
 
-      while ( !bfs.finished() ) { 
-	ResGWOutEdgeIt e=bfs;
-	if (res_graph.valid(e)) {
-	  if (bfs.isBNodeNewlyReached()) {
-	    dist.set(res_graph.head(e), dist[res_graph.tail(e)]+1);
+    while ( !bfs.finished() ) { 
+      ResGWOutEdgeIt e=bfs;
+      if (res_graph.valid(e)) {
+	if (bfs.isBNodeNewlyReached()) {
+	  dist.set(res_graph.head(e), dist[res_graph.tail(e)]+1);
+	  typename MG::Edge f=F.addEdge(res_graph_to_F[res_graph.tail(e)], res_graph_to_F[res_graph.head(e)]);
+	  original_edge.update();
+	  original_edge.set(f, e);
+	  residual_capacity.update();
+	  residual_capacity.set(f, res_graph.resCap(e));
+	} else {
+	  if (dist[res_graph.head(e)]==(dist[res_graph.tail(e)]+1)) {
 	    typename MG::Edge f=F.addEdge(res_graph_to_F[res_graph.tail(e)], res_graph_to_F[res_graph.head(e)]);
 	    original_edge.update();
 	    original_edge.set(f, e);
 	    residual_capacity.update();
 	    residual_capacity.set(f, res_graph.resCap(e));
-	  } else {
-	    if (dist[res_graph.head(e)]==(dist[res_graph.tail(e)]+1)) {
-	      typename MG::Edge f=F.addEdge(res_graph_to_F[res_graph.tail(e)], res_graph_to_F[res_graph.head(e)]);
-	      original_edge.update();
-	      original_edge.set(f, e);
-	      residual_capacity.update();
-	      residual_capacity.set(f, res_graph.resCap(e));
-	    }
 	  }
 	}
-	++bfs;
-      } //computing distances from s in the residual graph
+      }
+      ++bfs;
+    } //computing distances from s in the residual graph
 
-      bool __augment=true;
+    bool __augment=true;
 
-      while (__augment) {
-	__augment=false;
-	//computing blocking flow with dfs
-	DfsIterator< MG, typename MG::template NodeMap<bool> > dfs(F);
-	typename MG::template NodeMap<typename MG::Edge> pred(F);
-	pred.set(sF, INVALID);
-	//invalid iterators for sources
+    while (__augment) {
+      __augment=false;
+      //computing blocking flow with dfs
+      DfsIterator< MG, typename MG::template NodeMap<bool> > dfs(F);
+      typename MG::template NodeMap<typename MG::Edge> pred(F);
+      pred.set(sF, INVALID);
+      //invalid iterators for sources
 
-	typename MG::template NodeMap<Num> free(F);
+      typename MG::template NodeMap<Num> free(F);
 
-	dfs.pushAndSetReached(sF);      
-	while (!dfs.finished()) {
-	  ++dfs;
-	  if (F.valid(/*typename MG::OutEdgeIt*/(dfs))) {
-	    if (dfs.isBNodeNewlyReached()) {
-	      typename MG::Node v=F.aNode(dfs);
-	      typename MG::Node w=F.bNode(dfs);
-	      pred.set(w, dfs);
-	      if (F.valid(pred[v])) {
-		free.set(w, std::min(free[v], residual_capacity[dfs]));
-	      } else {
-		free.set(w, residual_capacity[dfs]); 
-	      }
-	      if (w==tF) { 
-		__augment=true; 
-		_augment=true;
-		break; 
-	      }
+      dfs.pushAndSetReached(sF);      
+      while (!dfs.finished()) {
+	++dfs;
+	if (F.valid(/*typename MG::OutEdgeIt*/(dfs))) {
+	  if (dfs.isBNodeNewlyReached()) {
+	    typename MG::Node v=F.aNode(dfs);
+	    typename MG::Node w=F.bNode(dfs);
+	    pred.set(w, dfs);
+	    if (F.valid(pred[v])) {
+	      free.set(w, std::min(free[v], residual_capacity[dfs]));
+	    } else {
+	      free.set(w, residual_capacity[dfs]); 
+	    }
+	    if (w==tF) { 
+	      __augment=true; 
+	      _augment=true;
+	      break; 
+	    }
 	      
-	    } else {
-	      F.erase(/*typename MG::OutEdgeIt*/(dfs));
-	    }
-	  } 
+	  } else {
+	    F.erase(/*typename MG::OutEdgeIt*/(dfs));
+	  }
+	} 
+      }
+
+      if (__augment) {
+	typename MG::Node n=tF;
+	Num augment_value=free[tF];
+	while (F.valid(pred[n])) { 
+	  typename MG::Edge e=pred[n];
+	  res_graph.augment(original_edge[e], augment_value); 
+	  n=F.tail(e);
+	  if (residual_capacity[e]==augment_value) 
+	    F.erase(e); 
+	  else 
+	    residual_capacity.set(e, residual_capacity[e]-augment_value);
 	}
-
-	if (__augment) {
-	  typename MG::Node n=tF;
-	  Num augment_value=free[tF];
-	  while (F.valid(pred[n])) { 
-	    typename MG::Edge e=pred[n];
-	    res_graph.augment(original_edge[e], augment_value); 
-	    n=F.tail(e);
-	    if (residual_capacity[e]==augment_value) 
-	      F.erase(e); 
-	    else 
-	      residual_capacity.set(e, residual_capacity[e]-augment_value);
-	  }
-	}
+      }
 	
-      }
+    }
             
-      return _augment;
-    }
+    return _augment;
+  }
 
 
 
@@ -883,75 +899,75 @@
   template <typename Graph, typename Num, typename CapMap, typename FlowMap>
   bool MaxFlow<Graph, Num, CapMap, FlowMap>::augmentOnBlockingFlow2() 
   {
-      bool _augment=false;
+    bool _augment=false;
 
-      ResGW res_graph(*g, *capacity, *flow);
+    ResGW res_graph(*g, *capacity, *flow);
       
-      //ReachedMap level(res_graph);
-      FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);
-      BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);
+    //ReachedMap level(res_graph);
+    FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);
+    BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);
 
-      bfs.pushAndSetReached(s);
-      DistanceMap<ResGW> dist(res_graph);
-      while ( !bfs.finished() ) { 
- 	ResGWOutEdgeIt e=bfs;
- 	if (res_graph.valid(e) && bfs.isBNodeNewlyReached()) {
- 	  dist.set(res_graph.head(e), dist[res_graph.tail(e)]+1);
- 	}
-	++bfs;
-      } //computing distances from s in the residual graph
+    bfs.pushAndSetReached(s);
+    DistanceMap<ResGW> dist(res_graph);
+    while ( !bfs.finished() ) { 
+      ResGWOutEdgeIt e=bfs;
+      if (res_graph.valid(e) && bfs.isBNodeNewlyReached()) {
+	dist.set(res_graph.head(e), dist[res_graph.tail(e)]+1);
+      }
+      ++bfs;
+    } //computing distances from s in the residual graph
 
       //Subgraph containing the edges on some shortest paths
-      ConstMap<typename ResGW::Node, bool> true_map(true);
-      typedef SubGraphWrapper<ResGW, ConstMap<typename ResGW::Node, bool>, 
-	DistanceMap<ResGW> > FilterResGW;
-      FilterResGW filter_res_graph(res_graph, true_map, dist);
+    ConstMap<typename ResGW::Node, bool> true_map(true);
+    typedef SubGraphWrapper<ResGW, ConstMap<typename ResGW::Node, bool>, 
+      DistanceMap<ResGW> > FilterResGW;
+    FilterResGW filter_res_graph(res_graph, true_map, dist);
 
-      //Subgraph, which is able to delete edges which are already 
-      //met by the dfs
-      typename FilterResGW::template NodeMap<typename FilterResGW::OutEdgeIt> 
- 	first_out_edges(filter_res_graph);
-      typename FilterResGW::NodeIt v;
-      for(filter_res_graph.first(v); filter_res_graph.valid(v); 
- 	  filter_res_graph.next(v)) 
+    //Subgraph, which is able to delete edges which are already 
+    //met by the dfs
+    typename FilterResGW::template NodeMap<typename FilterResGW::OutEdgeIt> 
+      first_out_edges(filter_res_graph);
+    typename FilterResGW::NodeIt v;
+    for(filter_res_graph.first(v); filter_res_graph.valid(v); 
+	filter_res_graph.next(v)) 
       {
  	typename FilterResGW::OutEdgeIt e;
  	filter_res_graph.first(e, v);
  	first_out_edges.set(v, e);
       }
-      typedef ErasingFirstGraphWrapper<FilterResGW, typename FilterResGW::
-	template NodeMap<typename FilterResGW::OutEdgeIt> > ErasingResGW;
-      ErasingResGW erasing_res_graph(filter_res_graph, first_out_edges);
+    typedef ErasingFirstGraphWrapper<FilterResGW, typename FilterResGW::
+      template NodeMap<typename FilterResGW::OutEdgeIt> > ErasingResGW;
+    ErasingResGW erasing_res_graph(filter_res_graph, first_out_edges);
 
-      bool __augment=true;
+    bool __augment=true;
 
-      while (__augment) {
+    while (__augment) {
 
- 	__augment=false;
-  	//computing blocking flow with dfs
-  	DfsIterator< ErasingResGW, 
-	  typename ErasingResGW::template NodeMap<bool> > 
-  	  dfs(erasing_res_graph);
- 	typename ErasingResGW::
-	  template NodeMap<typename ErasingResGW::OutEdgeIt> 
-	  pred(erasing_res_graph); 
- 	pred.set(s, INVALID);
-  	//invalid iterators for sources
+      __augment=false;
+      //computing blocking flow with dfs
+      DfsIterator< ErasingResGW, 
+	typename ErasingResGW::template NodeMap<bool> > 
+	dfs(erasing_res_graph);
+      typename ErasingResGW::
+	template NodeMap<typename ErasingResGW::OutEdgeIt> 
+	pred(erasing_res_graph); 
+      pred.set(s, INVALID);
+      //invalid iterators for sources
 
-  	typename ErasingResGW::template NodeMap<Num> 
-	  free1(erasing_res_graph);
+      typename ErasingResGW::template NodeMap<Num> 
+	free1(erasing_res_graph);
 
- 	dfs.pushAndSetReached(
-	  typename ErasingResGW::Node(
-	    typename FilterResGW::Node(
-	      typename ResGW::Node(s)
-	      )
-	    )
-	  );
- 	while (!dfs.finished()) {
- 	  ++dfs;
- 	  if (erasing_res_graph.valid(
- 		typename ErasingResGW::OutEdgeIt(dfs))) 
+      dfs.pushAndSetReached(
+			    typename ErasingResGW::Node(
+							typename FilterResGW::Node(
+										   typename ResGW::Node(s)
+										   )
+							)
+			    );
+      while (!dfs.finished()) {
+	++dfs;
+	if (erasing_res_graph.valid(
+				    typename ErasingResGW::OutEdgeIt(dfs))) 
  	  { 
   	    if (dfs.isBNodeNewlyReached()) {
 	  
@@ -961,10 +977,10 @@
  	      pred.set(w, /*typename ErasingResGW::OutEdgeIt*/(dfs));
  	      if (erasing_res_graph.valid(pred[v])) {
  		free1.set(w, std::min(free1[v], res_graph.resCap(
-				       typename ErasingResGW::OutEdgeIt(dfs))));
+								 typename ErasingResGW::OutEdgeIt(dfs))));
  	      } else {
  		free1.set(w, res_graph.resCap(
-			   typename ErasingResGW::OutEdgeIt(dfs))); 
+					      typename ErasingResGW::OutEdgeIt(dfs))); 
  	      }
 	      
  	      if (w==t) { 
@@ -976,33 +992,33 @@
  	      erasing_res_graph.erase(dfs);
 	    }
 	  }
-	}	
+      }	
 
-  	if (__augment) {
-   	  typename ErasingResGW::Node n=typename FilterResGW::Node(typename ResGW::Node(t));
-// 	  typename ResGW::NodeMap<Num> a(res_graph);
-// 	  typename ResGW::Node b;
-// 	  Num j=a[b];
-// 	  typename FilterResGW::NodeMap<Num> a1(filter_res_graph);
-// 	  typename FilterResGW::Node b1;
-// 	  Num j1=a1[b1];
-// 	  typename ErasingResGW::NodeMap<Num> a2(erasing_res_graph);
-// 	  typename ErasingResGW::Node b2;
-// 	  Num j2=a2[b2];
- 	  Num augment_value=free1[n];
- 	  while (erasing_res_graph.valid(pred[n])) { 
- 	    typename ErasingResGW::OutEdgeIt e=pred[n];
- 	    res_graph.augment(e, augment_value);
- 	    n=erasing_res_graph.tail(e);
- 	    if (res_graph.resCap(e)==0)
- 	      erasing_res_graph.erase(e);
+      if (__augment) {
+	typename ErasingResGW::Node n=typename FilterResGW::Node(typename ResGW::Node(t));
+	// 	  typename ResGW::NodeMap<Num> a(res_graph);
+	// 	  typename ResGW::Node b;
+	// 	  Num j=a[b];
+	// 	  typename FilterResGW::NodeMap<Num> a1(filter_res_graph);
+	// 	  typename FilterResGW::Node b1;
+	// 	  Num j1=a1[b1];
+	// 	  typename ErasingResGW::NodeMap<Num> a2(erasing_res_graph);
+	// 	  typename ErasingResGW::Node b2;
+	// 	  Num j2=a2[b2];
+	Num augment_value=free1[n];
+	while (erasing_res_graph.valid(pred[n])) { 
+	  typename ErasingResGW::OutEdgeIt e=pred[n];
+	  res_graph.augment(e, augment_value);
+	  n=erasing_res_graph.tail(e);
+	  if (res_graph.resCap(e)==0)
+	    erasing_res_graph.erase(e);
 	}
       }
       
-      } //while (__augment) 
+    } //while (__augment) 
             
-      return _augment;
-    }
+    return _augment;
+  }