Index: branches/cones-final/apps/matroid/src/matroid_from_graph.cc
===================================================================
--- branches/cones-final/apps/matroid/src/matroid_from_graph.cc	(revision 10003)
+++ branches/cones-final/apps/matroid/src/matroid_from_graph.cc	(revision 10314)
@@ -1,3 +1,3 @@
-/* Copyright (c) 1997-2010
+/* Copyright (c) 1997-2011
    Ewgenij Gawrilow, Michael Joswig (Technische Universitaet Darmstadt, Germany)
    http://www.polymake.de
@@ -78,6 +78,16 @@
       is_basis&=a[k];
     if (is_basis) {
-      bases.push_back(basis);
-      ++n_bases;
+      //we still have to check if basis defines a forest, or, equivalently, that its restriction to each connected
+      //component of G is connected
+      Graph<> t(n_nodes);
+      for (Entire<Set<int> >::const_iterator j=entire(basis); !j.at_end(); ++j)
+        t.edge(start_nodes[*j],end_nodes[*j]);
+      perl::Object T("Graph<>");
+      T.take("ADJACENCY")<<t;
+      const int T_n_comp=T.give("N_CONNECTED_COMPONENTS");
+      if (T_n_comp==n_components) {
+        bases.push_back(basis);
+        ++n_bases;
+      }
     }
   }