Department of Computer Science, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. zaki@cs.rpi.edu|Department of Computer Science, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. zaki@cs.rpi.edu|Department of Computer Science, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. zaki@cs.rpi.edu|Department of Computer Science, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. zaki@cs.rpi.edu