Relating coalgebraic notions of bisimulation
  The theory of coalgebras, for an endofunctor on a category, has been proposed as a general theory of transition systems. We investigate and relate four generalizations of bisimulation to this setting, providing conditions under which the four different generalizations coincide. We study transfinite sequences whose limits are the greatest bisimulations. 
Sam Staton (Laboratoire PPS, Universit\'e Paris 7)
cs.LO