Department of Computer Science, University of Western Ontario, N6A 5B7 London, Ontario, Canada. ilie@csd.uwo.ca.|Department of Computer Science, University of Western Ontario, N6A 5B7 London, Ontario, Canada. ilie@csd.uwo.ca.|Department of Computer Science, University of Western Ontario, N6A 5B7 London, Ontario, Canada. ilie@csd.uwo.ca.|National Centre for Biological Sciences (TIFR), GKVK Campus, Bellary Road, Bangalore 560065, India. mini@ncbs.res.in.