This dissertation contributes to analysis methods for infinite-state systems. The dissertation focuses on equivalence testing for two relevant classes of infinite-state systems: commutative context-free processes, and one-counter automata. As for equivalence notions, we investigate the classical bisimulation and simulation equivalences. The important point is that we allow for silent steps in t...

We show that the methodology for testing the existence and computation the greatest simulations and bisimulations, developed in the framework of fuzzy automata [M. Ćirić et al., Fuzzy Sets and Systems 186 (2012) 100–139, 208 (2012) 22–42], can be applied in a similar form to weighted automata over an additively idempotent semiring. We define two types of simulations and four types of bisimulati...

We investigate criteria to relate specifications and implementations belonging to conceptually different levels of abstraction. For this purpose, we introduce the generic concept of a vertical implementation relation, which is a family of binary relations indexed by a refinement function that maps abstract actions onto concrete processes and thus determines the basic connection between the abst...

This paper gives a logical characterization of probabilistic bisimulation for Markov processes introduced in BDEP97]. The thrust of that work was an extension of the notion of bisimulation to systems with continuous state spaces; for example for systems where the state space is the real numbers. In the present paper we study the logical characterization of probabilistic bisimulation for such ge...

Previous work of the author has developed probabilistic in-put/output automata (PIOA) as a formalism for modeling systems that exhibit concurrent and probabilistic behavior. Central to that work was the notion of the \behavior map" associated with a state of a PIOA. The present paper presents a new, simpler deenition for PIOA behavior maps, investigates the induced \same behavior map" equivalen...

We study the complexity of the Subgraph Bisimulation Problem, which stands to Graph Bisimulation as Subgraph Isomorphism stands to Graph Isomorphism and we prove its NP-Completeness. Our analysis is motivated by its applications to Semistructured Databases.

Klusener introduced a timed variant of branching bisimulation. In this paper it is shown that Klusener's axioms for nite process terms, together with two standard axioms for recursion, make a complete axiomatization for regular processes modulo timed branching bisimulation.

Formal notions of bisimulation and simulation relation play a central role for any kind of process algebra. This short paper sketches the main concepts for bisimulation and simulation relations for probabilistic systems, modelled by discreteor continuous-time Markov chains.

This paper shows that weak bisimulation congruence can be characterised as rooted weak bisimulation equivalence, even without making assumptions on the cardinality of the sets of states or actions of the processes under consideration.

We develop a new bisimulation (pseudo)metric for weighted finite automata (WFA) that generalizes Boreale’s linear bisimulation relation. Our metrics are induced by seminorms on the state space of WFA. Our development is based on spectral properties of sets of linear operators. In particular, the joint spectral radius of the transition matrices of WFA plays a central role. We also study continui...