private void initialize(){
  HashMap<Object,GVCongruenceClass> labelMap=new HashMap<Object,GVCongruenceClass>(10);
  for (Enumeration<GraphNode> e=valueGraph.enumerateVertices(); e.hasMoreElements(); ) {
    ValueGraphVertex v=(ValueGraphVertex)e.nextElement();
    Object label=v.getLabel();
    GVCongruenceClass c=findOrCreateCongruenceClass(label,labelMap);
    c.addVertex(v);
    v.setValueNumber(c.getValueNumber());
  }
}

private void initialize ( ) { HashMap < Object , GVCongruenceClass > labelMap = new HashMap < Object , GVCongruenceClass > ( 10 ) ; for ( Enumeration < GraphNode > e = valueGraph . enumerateVertices ( ) ; e . hasMoreElements ( ) ; ) { ValueGraphVertex v = ( ValueGraphVertex ) e . nextElement ( ) ; Object label = v . getLabel ( ) ; GVCongruenceClass c = findOrCreateCongruenceClass ( label , labelMap ) ; c . addVertex ( v ) ; v . setValueNumber ( c . getValueNumber ( ) ) ; } }
initialize the congruence classes , assuming that all nodes with the same label are congruent .
