reverting local changes, that I commited accidentally.

[[Imported from SVN: r1389]]

dune/istl/paamg/hierarchy.hh

@@ -828,11 +828,9 @@ namespace Dune
           // accumulate to fewer processors
           Matrix* redistMat= new Matrix();
           ParallelInformation* redistComm=0;
-          std::size_t nodomains = infoLevel->communicator().size()/3;
-
-          //dunknowns/(criterion.minAggregateSize()
-          //infoLevel->communicator().size(	     *criterion.coarsenTarget());
-          if( nodomains<=1 ||
+          std::size_t nodomains = dunknowns/(criterion.minAggregateSize()
+                                             *criterion.coarsenTarget());
+          if( nodomains<=criterion.minAggregateSize()/2 ||
               dunknowns <= criterion.coarsenTarget() )
             nodomains=1;