1. Computer Science Department, Universidad Carlos III de Madrid, Leganés, Spain. E-mails: dborrajo@ia.uc3m.es, carlos.linares@uc3m.es
2. Department of Information Systems Engineering, Ben-Gurion University, Be'er Sheva, Israel. E-mail: felner@bgu.ac.il
3. Computer Science Department, University of California, Los Angeles, CA, USA. E-mail: korf@cs.ucla.edu
4. Computer Science Department, Carnegie Mellon University, Pittsburgh, PA, USA. E-mail: maxim@cs.cmu.edu
5. Department of Computer Science, University of New Hampshire, Durham, NC, USA. E-mail: ruml@cs.unh.edu
6. Computer Science Department, University of Denver, Denver, CO, USA. E-mail: sturtevant@cs.du.edu