public static <T extends DC> Similarity getPhiSim(Set<Pair<T,T>> done)
  { if(done!=null)
    { if(done.next!=null)
      { return new Similarity(done.a.fst().delta(done.a.snd()).simi().getValue()+(getPhiSim(done.next).getValue()));
      }
      else
      { return new Similarity(done.a.fst().delta(done.a.snd()).simi().getValue());
      }  
    }
    else
    { return new Similarity(0.0);}  
  }