Symbolic Step Encodings for Object Based Communicating State Machines

Abstract

ABSTRACT:In this work, novel symbolic step encodings of the transition relation for object based communicating state machines are presented. This class of systems is tailored to capture the essential data manipulation features of UML state machines when enriched with a Java-like object oriented action language. The main contribution of the work is the generalization of the ∃-step semantics approach, which Rintanen has used for improving the efficiency of SAT based AI planning, to a much more complex class of systems. Furthermore, the approach is extended to employ a dynamic notion of independence. To evaluate the encodings, UML state machine models are automatically translated into NuSMV models and then symbolically model checked with NuSMV. Especially in bounded model checking (BMC), the ∃-step semantics often significantly outperforms the traditional interleaving semantics without any substantial blowup in the BMC encoding as a SAT formula.

Symbolic model checking of hierarchical UML state machines

“…at most one object can fire at most one transition during one time step. It is also possible to extend the encoding to use so-called ∃-step semantics [21] so that independent transitions in several objects can be executed at the same time step; see [11] for such an encoding for nonhierarchical state machines.…”

“…Furthermore, the experiments in [11] compare explicit-state model checking using Spin to BMC using the queue and control logic encoding presented here. The results indicate that symbolic model checking can complement explicit-state model checking even when analyzing asynchronous protocol models.…”

Checking Bounded Reachability in Asynchronous Systems by Symbolic Event Tracing

“…Using alternative execution semantics [18,11], several independent actions can occur in a single step of BMC, allowing longer executions to be analyzed without considerably growing the encoding. In [27], partial order reductions are implemented on top of BMC by adding a constraint that each pair of independent actions can occur at consecutive time steps only in one predefined order.…”

An SMT-Based Approach to Bounded Model Checking of Designs in State Transition Matrix

“…Our formalization of static and dynamic aspects of STM designs has been much influenced by the work on formalization and verification of hierarchical UML state machines [8], [9], [19], although hierarchical structure is not considered in our work so far. Regarding verification, the primary focus of our work, the work in [9] proposed to translate UML models into the model checker SPIN, and the work in [19] proposed a symbolic encoding approach of UML models into the input of NuSMV [20], through which BDD-based [21] and SAT-based [4] model checking could be conducted.…”

“…In this paper, a subset of STM notations is considered with the motivation of giving a precise description that can be formally verified. Adopting a similar approach used in [8], [9] for formalizing UML state machines, we formalize the structure of STMs and dynamic behaviors of a STM design.…”