Abstract A. Sokolova, E.P. de Vink and H. Woracek
Coalgebraic Weak Bisimulation for Action-Type Systems

We propose a coalgebraic definition of weak bisimulation for classes of
coalgebras obtained from bifunctors in the category Set. Weak bisimilarity for
a system is obtained as strong bisimilarity of a transformed system. The
particular transformation consists of two steps: First, the behavior on
actions is lifted to behavior on finite words. Second, the behavior on finite
words is taken modulo the hiding of internal or invisible actions, yielding
behavior on equivalence classes of words closed under silent steps. The
coalgebraic definition is validated by two correspondence results: one for the
classical notion of weak bisimulation of Milner, another for the notion of
weak bisimulation for generative probabilistic transition systems as advocated
by Baier and Hermanns.