List<Util.Pair<Integer, Integer>> getCandidates(
      Document document, int arg2Line, int connStart, int connEnd, int arg1Line) {
    List<Util.Pair<Integer, Integer>> candidates = new ArrayList<Util.Pair<Integer, Integer>>();

    int distance = 10;
    Sentence arg2Sentence = document.getSentence(arg2Line);
    // String conn = arg2Sentence.toString(connStart, connEnd).toLowerCase();
    // String category = connAnalyzer.getCategory(conn);
    int connHeadPos = connAnalyzer.getHeadWord(arg2Sentence.getParseTree(), connStart, connEnd);
    SimpleDepGraph arg2DepGraph = document.getDepGraph(arg2Line);
    List<Integer> reachable = arg2DepGraph.getReachableIndices(connHeadPos, false, distance);
    for (Integer i : reachable) {
      if (arg2Sentence.get(i).getTag("POS").matches("VB.*|NNS?|JJ.*|MD")) {
        candidates.add(new Util.Pair<Integer, Integer>(arg2Line, i));
      }
    }
    Tree mainHead = headAnalyzer.getCollinsHead(arg2Sentence.getParseTree().getChild(0));
    if (mainHead != null) {
      int mainHeadPos = treeAnalyzer.getLeafPosition(arg2Sentence.getParseTree(), mainHead);
      List<String> pathAsList = arg2DepGraph.getPathAsList(connHeadPos, mainHeadPos, false);
      if (pathAsList != null) {
        distance = distance - (1 + pathAsList.size());
      } else {
        // System.out.println("No path from connHead to mainHead!");
        distance--;
      }
    }
    // if (arg1Line == arg2Line) return candidates;

    for (int i = arg2Line - 1; i >= 0 && distance >= 0; i--) {
      Sentence sentence = document.getSentence(i);
      SimpleDepGraph depGraph = document.getDepGraph(i);
      mainHead = headAnalyzer.getCollinsHead(sentence.getParseTree().getChild(0));
      if (mainHead == null) {
        distance--;
        continue;
      }
      int mainHeadPos = treeAnalyzer.getLeafPosition(sentence.getParseTree(), mainHead);
      reachable = depGraph.getReachableIndices(mainHeadPos, false, distance);
      if (reachable == null) {
        distance--;
        continue;
      }
      for (Integer j : reachable) {
        if (sentence.get(j).getTag("POS").matches("VB.*|NNS?|JJ.*|MD")) {
          candidates.add(new Util.Pair<Integer, Integer>(i, j));
        }
      }
      distance -= 2;
    }
    return candidates;
  }
  private PropertyList addDependencyFeatures(
      PropertyList pl,
      Document doc,
      Pair<Integer, Integer> candidate,
      int arg2Line,
      int arg2HeadPos,
      int connStart,
      int connEnd) {
    Sentence arg2Sentence = doc.getSentence(arg2Line);
    String conn = arg2Sentence.toString(connStart, connEnd);
    String category = connAnalyzer.getCategory(conn.toLowerCase());
    int connHeadPos = connAnalyzer.getHeadWord(arg2Sentence.getParseTree(), connStart, connEnd);

    int arg1Line = candidate.first();
    Tree arg1Tree = doc.getTree(arg1Line);
    int arg1HeadPos = candidate.second();

    List<String> path = new ArrayList<String>();
    if (arg1Line == arg2Line) {
      SimpleDepGraph depGraph = doc.getDepGraph(arg1Line);
      List<String> tmpPath = depGraph.getPathAsList(connHeadPos, arg1HeadPos, false);
      if (tmpPath != null) {
        path.addAll(tmpPath);
      } else {
        path.add("null");
      }
    } else {
      Tree arg2Root = arg2Sentence.getParseTree();
      Tree mainHead = headAnalyzer.getCollinsHead(arg2Root.getChild(0));
      int mainHeadPos = treeAnalyzer.getLeafPosition(arg2Root, mainHead);
      if (mainHeadPos != -1) {
        SimpleDepGraph depGraph = doc.getDepGraph(arg2Line);
        List<String> tmpPath = depGraph.getPathAsList(connHeadPos, mainHeadPos, false);
        if (tmpPath != null) {
          path.addAll(tmpPath);
        } else {
          path.add("null");
        }
      }
      for (int i = 0; i < Math.abs(arg1Line - arg2Line); i++) {
        path.add("SENT");
      }

      Tree arg1Root = arg1Tree;
      mainHead = headAnalyzer.getCollinsHead(arg1Root.getChild(0));
      mainHeadPos = treeAnalyzer.getLeafPosition(arg1Root, mainHead);
      if (mainHeadPos != -1) {
        SimpleDepGraph depGraph = doc.getDepGraph(arg1Line);
        List<String> tmpPath = depGraph.getPathAsList(mainHeadPos, arg1HeadPos, false);
        if (tmpPath != null) {
          path.addAll(tmpPath);
        } else {
          path.add("null");
        }
      }
    }

    StringBuilder sbPath = new StringBuilder();
    StringBuilder sbPathWithoutCC = new StringBuilder();
    StringBuilder sbPathWithoutRep = new StringBuilder();

    String prev = "";
    for (String node : path) {
      sbPath.append(node).append(":");
      if (!node.matches("cc|-cc")) {
        sbPathWithoutCC.append(node).append(":");
      }
      if (!node.equals(prev)) {
        sbPathWithoutRep.append(node).append(":");
      }
      prev = node;
    }
    // M-dependency path
    pl = PropertyList.add("M=" + sbPath.toString(), 1.0, pl);
    // Q-M&C
    pl = PropertyList.add("Q=" + "CONN-" + conn + '&' + "M-" + sbPath.toString(), 1.0, pl);
    // T-M&R
    pl = PropertyList.add("T=" + "CAT-" + category + '&' + "M-" + sbPath.toString(), 1.0, pl);
    // O-collapsed path without cc
    pl = PropertyList.add("O=" + sbPathWithoutCC.toString(), 1.0, pl);
    // P-collapsed path without repetition
    pl = PropertyList.add("P=" + sbPathWithoutRep.toString(), 1.0, pl);

    return pl;
  }
  private PropertyList addConstituentFeatures(
      PropertyList pl,
      Document doc,
      Pair<Integer, Integer> candidate,
      int arg2Line,
      int arg2HeadPos,
      int connStart,
      int connEnd) {
    Sentence arg2Sentence = doc.getSentence(arg2Line);
    String conn = arg2Sentence.toString(connStart, connEnd);
    int connHeadPos = connAnalyzer.getHeadWord(arg2Sentence.getParseTree(), connStart, connEnd);

    int arg1Line = candidate.first();
    Tree arg1Tree = doc.getTree(arg1Line);
    int arg1HeadPos = candidate.second();

    List<String> path = new ArrayList<String>();
    List<String> pathWithoutPOS = new ArrayList<String>();

    if (arg1Line == arg2Line) {
      Tree root = arg1Tree;
      List<Tree> leaves = root.getLeaves();
      List<Tree> treePath = root.pathNodeToNode(leaves.get(connHeadPos), leaves.get(arg1HeadPos));
      if (treePath != null) {
        for (Tree t : treePath) {
          if (!t.isLeaf()) {
            path.add(t.value());
            if (!t.isPreTerminal()) {
              pathWithoutPOS.add(t.value());
            }
          }
        }
      }
    } else {
      Tree arg2Root = arg2Sentence.getParseTree();
      Tree mainHead = headAnalyzer.getCollinsHead(arg2Root.getChild(0));
      List<Tree> leaves = arg2Root.getLeaves();
      int mainHeadPos = treeAnalyzer.getLeafPosition(arg2Root, mainHead);
      if (mainHeadPos != -1) {
        List<Tree> treePath =
            arg2Root.pathNodeToNode(leaves.get(connHeadPos), leaves.get(mainHeadPos));
        if (treePath != null) {
          for (Tree t : treePath) {
            if (!t.isLeaf()) {
              path.add(t.value());
              if (!t.isPreTerminal()) {
                pathWithoutPOS.add(t.value());
              }
            }
          }
        }
      }
      for (int i = 0; i < Math.abs(arg1Line - arg2Line); i++) {
        path.add("SENT");
        pathWithoutPOS.add("SENT");
      }
      Tree arg1Root = arg1Tree;
      mainHead = headAnalyzer.getCollinsHead(arg1Root.getChild(0));
      leaves = arg1Root.getLeaves();
      mainHeadPos = treeAnalyzer.getLeafPosition(arg1Root, mainHead);
      if (mainHeadPos != -1) {
        List<Tree> treePath =
            arg1Root.pathNodeToNode(leaves.get(mainHeadPos), leaves.get(arg1HeadPos));
        if (treePath != null) {
          for (Tree t : treePath) {
            if (!t.isLeaf()) {
              path.add(t.value());
              if (!t.isPreTerminal()) {
                pathWithoutPOS.add(t.value());
              }
            }
          }
        }
      }
    }
    // H-full path
    // L-C&H
    StringBuilder fullPath = new StringBuilder();
    for (String node : path) {
      fullPath.append(node).append(":");
    }
    pl = PropertyList.add("H=" + fullPath.toString(), 1.0, pl);
    pl = PropertyList.add("L=CONN-" + conn + "&" + "H-" + fullPath.toString(), 1.0, pl);

    // I-length of path
    pl = PropertyList.add("I=" + path.size(), 1.0, pl);

    // J-collapsed path without part of speech
    // K-collapsed path without repititions
    fullPath = new StringBuilder();
    StringBuilder collapsedPath = new StringBuilder();
    String prev = "";
    for (String node : pathWithoutPOS) {
      fullPath.append(node).append(":");
      if (!node.equals(prev)) {
        collapsedPath.append(node).append(":");
      }
      prev = node;
    }
    pl = PropertyList.add("J=" + fullPath.toString(), 1.0, pl);
    pl = PropertyList.add("K=" + collapsedPath.toString(), 1.0, pl);

    return pl;
  }