code: private char matchPrefix(String str1, String str2) {
          //here always str1.startsWith(str2) colorless!color
          char rel = IMappingElement.IDK;
          int spacePos1 = str1.indexOf(' ');
          String suffix = str1.substring(str2.length());
          if (-1 < spacePos1 && !suffixes.containsKey(suffix)) {//check suffixes - pole vault=pole vaulter
              if (str2.length() == spacePos1) {//plant part<plant
                  rel = IMappingElement.LESS_GENERAL;
              } else {//plant part<plan
                  String left = str1.substring(0, spacePos1);
                  char secondRel = match(left, str2);
                  if (IMappingElement.MORE_GENERAL == secondRel ||
                          IMappingElement.EQUIVALENCE == secondRel) {
                      rel = IMappingElement.LESS_GENERAL;
                  } else { //?,<,!
                      rel = secondRel;
                  }
              }
          } else {
              //spelling: -tree and tree
              if (suffix.startsWith("-")) {
                  suffix = suffix.substring(1);
              }
              if (suffix.endsWith("-") || suffix.endsWith(";") || suffix.endsWith(".") || suffix.endsWith(",") || suffix.endsWith("-")) {
                  suffix = suffix.substring(0, suffix.length() - 1);
              }
              if (suffixes.containsKey(suffix)) {
                  rel = suffixes.get(suffix);
                  rel = reverseRelation(rel);
              }
  
              //another approximation = Gversion4
  //            if (rel == MatchManager.LESS_GENERAL || rel == MatchManager.MORE_GENERAL) {
  //                rel = MatchManager.EQUIVALENCE;
  //            }
          }
  
          //filter = Gversion3
  //        if (MatchManager.LESS_GENERAL == rel || MatchManager.MORE_GENERAL == rel) {
  //            rel = MatchManager.EQUIVALENCE;
  //        }
  
          return rel;
      }
docs: Computes relation with prefix matcher.
  
  @param str1 the source input
  @param str2 the target input
  @return synonym, more general, less general or IDK relation