private void addInstancesThroughPipe(
      PDTBRelation relation,
      Document document,
      int arg1Line,
      int arg2Line,
      InstanceList instanceList) {
    // System.out.println("Relation: " + relation.toString());
    // System.out.println("arg1Line: " + arg1Line);
    // System.out.println("arg2Line: " + arg2Line);

    String connectiveGornAddress = relation.getConnectiveGornAddress();
    Tree arg2Tree = document.getTree(arg2Line);
    List<Tree> connHeadLeaves =
        connAnalyzer.getConnHeadLeaves(arg2Tree, connectiveGornAddress, relation.getConnHead());
    if (connHeadLeaves.isEmpty()) return;

    int connStart = treeAnalyzer.getLeafPosition(arg2Tree, connHeadLeaves.get(0));
    int connEnd =
        treeAnalyzer.getLeafPosition(arg2Tree, connHeadLeaves.get(connHeadLeaves.size() - 1));
    if ((connEnd - connStart) > 4) { // handle if..else, etc.
      connEnd = connStart;
    }

    // consider only the first sentence in case of multi-line argument1
    String arg1GornAddress = relation.getArg1GornAddress();
    Tree arg1Tree = document.getTree(arg1Line);
    List<Tree> arg1GornNodes = getArgGornNodes(arg1Tree, arg1Line, arg1GornAddress);

    Tree syntacticHead = headAnalyzer.getSyntacticHead(arg1Tree, arg1GornNodes);
    int arg1HeadPos = treeAnalyzer.getLeafPosition(arg1Tree, syntacticHead);

    String arg2GornAddress = relation.getArg2GornAddress();
    List<Tree> arg2GornNodes = getArgGornNodes(arg2Tree, arg2Line, arg2GornAddress);

    Tree arg2SyntacticHead = headAnalyzer.getSyntacticHead(arg2Tree, arg2GornNodes);
    int arg2HeadPos = treeAnalyzer.getLeafPosition(arg2Tree, arg2SyntacticHead);

    if (arg2HeadPos == -1) {
      System.out.println("arg2Head == -1");
      return;
    }
    if (arg1HeadPos == -1) {
      System.out.println("arg1Head == -1");
      return;
    }
    int trueCandidate = -1;
    List<Pair<Integer, Integer>> candidates =
        getCandidates(document, arg2Line, connStart, connEnd, arg1Line);
    for (int i = 0; i < candidates.size(); i++) {
      Pair<Integer, Integer> candidate = candidates.get(i);
      if (candidate.first() == arg1Line && candidate.second() == arg1HeadPos) {
        trueCandidate = i;
        break;
      }
    }
    if (trueCandidate == -1) {
      // trueCandidate = candidates.size();
      // candidates.add(new Pair<Integer, Integer>(arg1Line, arg1HeadPos));
      // System.out.println("Covered!");
      System.out.println("true candidate == -1!!!");
      System.out.println(syntacticHead.value());
    } else {
      int extractArg2 =
          ARG2_EXTRACTOR.extractArg2(
              document.getSentence(arg2Line),
              document.getTree(arg2Line),
              document.getDepGraph(arg2Line),
              connStart,
              connEnd);
      if (extractArg2 == -1) {
        extractArg2 = 0;
        System.out.println("Arg2 == -1!!!!!!!!!!!!!!!!!");
      }
      // Arg1RankInstance instance = new Arg1RankInstance(document, candidates, arg2Line,
      // extractArg2, connStart, connEnd, trueCandidate);

      Arg1RankInstance instance =
          new Arg1RankInstance(
              document, candidates, arg2Line, arg2HeadPos, connStart, connEnd, trueCandidate);
      instanceList.addThruPipe(instance);
    }
  }