code: public static double compuNatureFreq(NatureTerm from, NatureTerm to) {
          double twoWordFreq = NatureLibrary.getTwoNatureFreq(from.termNature.nature, to.termNature.nature);
          if (twoWordFreq == 0) {
              twoWordFreq = Math.log(from.selfScore + to.selfScore);
          }
          double score = from.score + Math.log((from.selfScore + to.selfScore) * twoWordFreq) + to.selfScore;
          return score;
      }
docs: 两个词性之间的分数计算
  
  @param from
  @param to
  @return