Bisimulation lattice of chi processes

Chi calculus was proposed as a process algebra that has a uniform treatment of names. The paper carries out a systematic study of bisimilarities for chi processes. The notion of L-bisimilarity is introduced to give a possible classification of bisimilarities on chi processes. It is shown that the set of L-bisimilarities forms a four element lattice and that well-known bisimilarities for chi processes fit into the lattice hierarchy. The four distinct L-bisimilarities give rise to four congruence relations. Complete axiomatization system is given for each of the four relations. The bisimulation lattice of asynchronous chi processes and that of asymmetric chi processes are also investigated. It turns out that the former consists of two elements while the latter twelve elements. Finally it is pointed out that the asynchronous asymmetric chi calculus has a bisimulation lattice of eight elements.