public double strength(int idx)
  {
    if(!_ok || idx<0 || idx>=h_index_size()){
      return -1.0;
    }
    return 100.0*qFrq(idx)/sFrq(idx);
  }
Class for accessing the concept network automata.

@author  <a href="mailto:boros@yahoo-inc.com">Peter Boros</a>
fsa/src/main/java/com/yahoo/fsa/conceptnet/ConceptNet.java