// dictionary and connectors have to be ciSets
static Chain<S> constructWordFromCISet_withConnectors(S word, Set<S> dictionary, Set<S> connectors) {
  ifdef constructWordFromCISet_withConnectors_debug
  print("checking: " + word);
  endifdef
  if (contains(dictionary, word)) ret Chain<S>(word);
  for ping (int i = l(word)-1; i > 0; i--) {
    S prefix = takeFirst(i, word);
    if (contains(dictionary, prefix)) {
      S rest = substring(word, i);
      
      // try connector
      LS matchingConnectors = reversed(prefixesOfIC(connectors, rest));
      for (S conn : matchingConnectors) {
        Chain<S> chain = constructWordFromCISet_withConnectors(dropPrefixIC(conn, rest), dictionary, connectors);
        if (chain != null)
          ret Chain<S>(prefix, Chain<S>(conn, chain));
      }
      
      // try no connector
      Chain<S> chain = constructWordFromCISet_withConnectors(rest, dictionary, connectors);
      if (chain != null)
        ret Chain<S>(prefix, chain);
    }
  }
  null;
}