1. Department of Computer Science, Haifa University, Haifa 31905, Israel; Department of Computer and Information Science, Polytechnic University, Six MetroTech Center, Brooklyn, NY 11201-3840.
2. Incyte Pharmaceuticals, 3174 Porter Drive, Palo Alto, CA 94304.
3. Department of Computer Science, Bar-Ilan University, Ramat Gan 52900, Israel.