State Transition System Research Articles

Interval diffracted particle filter

A new particle filter based on interval filter and particle diffraction is proposed for the on-line estimation of non-Gaussian and nonlinear system with uncertain dynamics modeling. This algorithm computes the more accurate importance density function, which integrates the latest observations into the system state transition density, so that the approximation to the system posterior density is improved. At the same time, the workload of calculation is reduced by treating particle diffraction like light diffraction. A simulation experiment on the SINS/CNS (strap-down inertial navigation system/celestial navigation system) attitude estimation shows the effectiveness and robustness of the improved algorithm.

Automated Computing of the Maximal Number of Handled Clients for Client-Server Systems

In many real software systems like Client-Server systems, one can identify a stable part (server, instance handler, control component) and a number of uniform components of the same type (clients, instances, users). When analysing performance and correctness of these systems we need to answer questions like "What is the maximal possible number of clients which can be handled simultaneously?" or more generally "What is the maximal possible number of clients which are in the some special situation when the control component is in a particular state?". In the paper we propose an automated technique solving such questions. For Client-Server systems we reduce the problem of finding the upper bound on the number of handled clients to the formal verification of reachability properties in infinite state transition systems. For the verification task we propose an efficient and fully automated algorithm which combines several techniques proposed in existing literature. Applying the algorithm we verify models of several previously published systems.

TOWARDS A SEMANTIC STATE TRANSITION SYSTEM FOR AUTOMATED GENERATION OF DATA FLOW IN WEB SERVICE COMPOSITION

Most of the work on automated web service composition has focused so far on composition of stateful web services. This level of composition so-called "Process Level" considers web services with their internal and complex behaviors. At process level formal models such as State Transition Systems (STS from now) or Interface Automata are the most appropriate models to represent the internal behavior of stateful web services. However such models focus only on semantics of their behaviors and unfortunately not on semantics of actions and their parameters. In this paper, we suggest to extend the STS model, by following the WSMO based annotation for Abstract State Machine. This semantic enhancement of STS so called S2 TS will enable to model semantics of internal behaviors and semantics of their actions together with their input and output parameters. Secondly, we will focus on automated generation of data flow (or the process to perform automated assignments between parameter of services involved in a composition). Thus we do not restrict to assignments of exact parameters (which is practically never used in industrial scenario) but extend assignments to semantically close parameters (e.g., through a subsumption matching) in the same ontology. Our system is implemented and interacting with web services dedicated to Telecommunication scenarios. The preliminary evaluation results showed high efficiency and effectiveness of the proposed approach.

On Controllability and Observability of Linear Time-varying Singular Systems

摘要: 讨论了线性时变系统和线性时变广义系统的两个基本问题, 得到了两种判定时变系统能控性与能观性的必要条件, 该判定条件只依赖于系统矩阵A(t)和输入矩阵B(t), 不必计算系统的系统状态转移矩阵, 使得判别时变系统能控性与能观性易于实现. 说明了本文结论是线性定常系统相应结论的自然扩展. 对进一步深入研究时变系统和时变广义系统具有实际启发作用. 关键词: 时变系统 / 广义系统 / 能控性 / 状态转移矩阵

Model Checking the Inconsistency and Circularity in Rule-Based Expert Systems

In the past several years, various techniques were proposed to analyze various types of structural errors, such as inconsistency (conflict rules), and circularity (circular depending rules), of rule-based systems. Model checking is a technique for the verification of temporal logic specifications in state transition systems. In this paper, we model the rule-based systems as finite state transition systems and express consistency and acyclic as Linear Temporal Logic (LTL) logic formula and then use the technique of model checking to detect inconsistency and circularity in Rule-Based Systems with the model checker NuSMV.

Formalization and Implementation of Modern SAT Solvers

Most, if not all, state-of-the-art complete SAT solvers are complex variations of the DPLL procedure described in the early 1960’s. Published descriptions of these modern algorithms and related data structures are given either as high-level state transition systems or, informally, as (pseudo) programming language code. The former, although often accompanied with (informal) correctness proofs, are usually very abstract and do not specify many details crucial for efficient implementation. The latter usually do not involve any correctness argument and the given code is often hard to understand and modify. This paper aims to bridge this gap by presenting SAT solving algorithms that are formally proved correct and also contain information required for efficient implementation. We use a tutorial, top-down, approach and develop a SAT solver, starting from a simple design that is subsequently extended, step-by-step, with a requisite series of features. The heuristic parts of the solver are abstracted away, since they usually do not affect solver correctness (although they are very important for efficiency). All algorithms are given in pseudo-code and are accompanied with correctness conditions, given in Hoare logic style. The correctness proofs are formalized within the Isabelle theorem proving system and are available in the extended version of this paper. The given pseudo-code served as a basis for our SAT solver argo-sat.

A structure-preserving algorithm for the minimum H ∞ norm computation of finite-time state feedback control problem

The algorithm being developed here is based on the generating function approach for finite-time H ∞ control and application of canonical transformation of linear Hamiltonian system. First, an equivalent finite-time H ∞ control law in terms of the third-type generating function is derived. Then, by using symplectic structure of the Hamiltonian system's state transition matrix, a group of matrix recursive formulae are deduced for the evaluation of the finite-time H ∞ control law. Combining with a matrix singularity testing procedure, this recursive algorithm verifies the existence condition of sub-optimal H ∞ controllers and gives the minimum H ∞ norm of finite-time control systems. Inherited from the canonical transformation, the matrix recursive formulae have a standard symplectic form; this structure-preserving property helps facilitate reliable and effective computation. Numerical results show the effectiveness of the proposed algorithm.

On metrics for probabilistic systems: Definitions and algorithms

In this paper, we consider the behavioral pseudometrics for probabilistic systems, which are a quantitative analogue of probabilistic bisimilarity in the sense that the distance zero captures the probabilistic bisimilarity. The model we are interested in is probabilistic automata, which are based on state transition systems and make a clear distinction between probabilistic and nondeterministic choices. The pseudometrics are defined as the greatest fixpoint of a monotonic functional on the complete lattice of state metrics. A distinguished characteristic of this pseudometric lies in that it does not discount the future, which addresses some algorithmic challenges to compute the distance of two states in the model. We solve this problem by providing an approximation algorithm: up to any desired degree of accuracy ε , the distance can be approximated to within ε in time exponential in the size of the model and logarithmic in 1 ε . One of the key ingredients of our algorithm is to express a pseudometric being a post-fixpoint as the elementary sentence over real closed fields, which allows us to exploit Tarski’s decision procedure, together with the binary search to approximate the behavioral distance.

VERIFICATION OF PLC PROGRAMS WRITTEN IN FBD WITH VIS

Verification of programmable logic controller (PLC) programs written in IEC 61131-3 function block diagram (FBD) is essential in the transition from the use of traditional relay-based analog systems to PLC-based digital systems. This paper describes effective use of the well-known verification tool VIS for automatic verification of behavioral equivalences between successive FBD revisions. We formally defined FBD semantics as a state-transition system, developed semantic-preserving translation rules from FBD to Verilog programs, implemented a software tool to support the process, and conducted a case study on a subset of FBDs for APR-1400 reactor protection system design.

Functional metamodels for systems and software

The modeling, analysis and design of systems is generally based on many formalisms to describe discrete and/or continuous behaviors, and to map these descriptions into a specific platform. In this context, the article proposes the concept of functional metamodeling to capture, then to integrate modeling languages. The concept offers an alternative to standard Model Driven Engineering (MDE) and is well adapted to mathematical descriptions such as the ones found in system modeling. As an application, a set of functional metamodels is proposed for dataflows (usable to model continuous behaviors), state-transition systems (usable to model discrete behaviors) and a metamodel for actions (to model interactions with a target platform and concurrent execution). A model of a control architecture for a legged robot is proposed as an application of these modeling languages.

Labelled State Transition Systems

Labelled State Transition SystemsThis article introduces labelled state transition systems, where transitions may be labelled by words from a given alphabet. Reduction relations from [4] are used to define transitions between states, acceptance of words, and reachable states. Deterministic transition systems are also defined.

A formal analysis of database replication protocols with SI replicas and crash failures

This paper provides a formal specification and proof of correctness of a basic Generalized Snapshot Isolation certification-based data replication protocol for database middleware architectures. It has been modeled using a state transition system, as well as the main system components, allowing a perfect match with the usual deployment in a middleware system. The proof encompasses both safety and liveness properties, as it is commonly done for a distributed algorithm. Furthermore, a crash failure model has been assumed for the correctness proof, although recovery analysis is not the aim of this paper. This allows an easy extension toward a crash-recovery model support in future works. The liveness proof focuses in the uniform commit: if a site has committed a transaction, the rest of sites will either commit it or it would have crashed.

Inclusion dynamics hybrid automata

Hybrid systems are dynamical systems with the ability to describe mixed discrete-continuous evolution of a wide range of systems. Consequently, at first glance, hybrid systems appear powerful but recalcitrant, neither yielding to analysis and reasoning through a purely continuous-time modeling as with systems of differential equations, nor open to inferential processes commonly used for discrete state-transition systems such as finite state automata. A convenient and popular model, called hybrid automata, was introduced to model them and has spurred much interest on its tractability as a tool for inference and model checking in a general setting. Intuitively, a hybrid automaton is simply a “finite-state” automaton with each state augmented by continuous variables, which evolve according to a set of well-defined continuous laws, each specified separately for each state. This article investigates both the notion of hybrid automaton and the model checking problem over such a structure. In particular, it relates first-order theories and analysis results on multivalued maps and reduces the bounded reachability problem for hybrid automata whose continuous laws are expressed by inclusions ( x ′ ∈ f ( x , t ) ) to a decidability problem for first-order formulæ over the reals. Furthermore, the paper introduces a class of hybrid automata for which the reachability problem can be decided and shows that the problem of deciding whether a hybrid automaton belongs to this class can be again decided using first-order formulæ over the reals. Despite the fact that the bisimulation quotient for this class of hybrid automata can be infinite, we show that our techniques permit effective model checking for a nontrivial fragment of CTL.

Janus: A dual-purpose analytical model for understanding, characterizing and countermining multi-stage collusive attacks in enterprise networks

Multi-stage collusive attack (MSCA) covers a large class of attack variants, and commonly refers to an attack consists of several atomic attack stages and is enforced by a number of coordinated attack parties. The rich history of the development of countermeasures for specific MSCA, e.g., DDoS, worms, has shown that it is the special spatio-temporal characteristic that causes the prevention, detection and response of MSCA to be challenging. Instead of focusing on fine-grained specific attack analysis, this paper presents a model from high-level viewpoint, aiming at characterizing the behaviors of MSCA in terms of key spatio-temporal properties for better understanding and more effective design of countermeasures. The model is specifically developed for two purposes: First, it sheds light on the fundamental elements of an MSCA by examining its spatio-temporal related observations, and formulating attacker behavior as a reward-directed Markov decision process; Second, it assists security administrator in identifying the potential causal relationship of system vulnerabilities based on the reports of deployed security tools, so as to suggest appropriate actions. Taking the model as a basis, two meta-heuristic algorithms are designed. Specifically, attackers nondeterministic trail search (ANTS) is developed for approximately searching attack schemes with the minimum attack cost, and attacker’ s pivots discovery via backward searching (APD-BS) is designed for examining the pivots of attack schemes, namely the key observations associated with system state transitions during an attack. Finally, a proof-of-concept validation is conducted using a simulated enterprise network under DDoS attack, which is a typical MSCA variant.

GEKF, GUKF and GGPF based prediction of chaotic time-series with additive and multiplicative noises

On the assumption that random interruptions in the observation process are modelled by a sequence of independent Bernoulli random variables, this paper generalize the extended Kalman filtering (EKF), the unscented Kalman filtering (UKF) and the Gaussian particle filtering (GPF) to the case in which there is a positive probability that the observation in each time consists of noise alone and does not contain the chaotic signal (These generalized novel algorithms are referred to as GEKF, GUKF and GGPF correspondingly in this paper). Using weights and network output of neural networks to constitute state equation and observation equation for chaotic time-series prediction to obtain the linear system state transition equation with continuous update scheme in an online fashion, and the prediction results of chaotic time series represented by the predicted observation value, these proposed novel algorithms are applied to the prediction of Mackey–Glass time-series with additive and multiplicative noises. Simulation results prove that the GGPF provides a relatively better prediction performance in comparison with GEKF and GUKF.

A theoretical investigation of regular equivalences for fuzzy graphs

The notion of regular equivalence or bisimulation arises in different applications, such as positional analysis of social networks and behavior analysis of state transition systems. The common characteristic of these applications is that the system under modeling can be represented as a graph. Thus, regular equivalence is a notion used to capture the similarity between nodes based on their linking patterns with other nodes. According to Borgatti and Everett, two nodes are regularly equivalent if they are equally related to equivalent others. In recent years, fuzzy graphs have also received considerable attention because they can represent both the qualitative relationships and the degrees of connection between nodes. In this paper, we generalize the notion of regular equivalence to fuzzy graphs based on two alternative definitions of regular equivalence. While the two definitions are equivalent for crisp graphs, they induce different generalizations for fuzzy graphs. The first generalization, called regular similarity, is based on the characterization of regular equivalence as an equivalence relation that commutes with the underlying graph edges. The regular similarity is then a fuzzy binary relation that specifies the degree of similarity between nodes in the graph. The second generalization, called generalized regular equivalence, is based on the definition of coloring. A coloring is a mapping from the set of nodes to a set of colors. A coloring is regular if nodes that are mapped to the same color, have the same colors in their neighborhoods. Hence, generalized regular equivalence is an equivalence relation that can determine a crisp partition of the nodes in a fuzzy graph.

Automatic generation of test specifications for coverage of system state transitions

Adequate system testing of present day application programs requires satisfactory coverage of system states and transitions. This can be achieved by using a system state model. However, the system state models are rarely constructed by system developers, as these are large and complex. The only state models that are constructed by the developers are those of individual objects. However test case generation for state-based system testing based on traversal of statecharts of individual objects appears to be infeasible, since system test cases would have to be specified in the form of scenario sequences rather than transitions on individual object statecharts. In this paper, we propose a novel approach to coverage of elementary transition paths of an automatically synthesized system state model. Our technique for coverage of elementary transition paths would also ensure coverage of all states and transitions of the system model.

Availability of K- out- of- N: G systems with non-identical components subject to repair priorities

In this paper, a K- out- of- N: G system with N categories of components is studied. Each component category is characterized by its own failure and repair rates. There are R repair facilities, and repair priorities are specified between the N non-identical components. An algorithm for automatic construction of the system state transition diagram is presented. The stationary availability of each component and that of the system are evaluated by using a multi-dimensional Markov model. We show how this model can be represented as a network of stochastic automata with state-dependent transitions that can be implemented via generalized tensor (or Kronecker) algebra. For the efficiency assessment, an analog Monte Carlo simulation model is developed. Experiments are then conducted and simulation results are compared to those obtained by the proposed approach.

Cognitive and synthetic behavior of avatars in intelligent virtual environments

In intelligent virtual environments (IVEs), it is a challenging research issue to provide the intelligent virtual actors (or avatars) with the ability of visual perception and rapid response to virtual world events. Modeling an avatar’s cognitive and synthetic behavior appropriately is of paramount important in IVEs. We propose a new cognitive and behavior modeling methodology that integrates two previously developed complementary approaches. We present expression cloning, walking synthetic behavior modeling, and an autonomous agent cognitive model for driving an avatar’s behavior. Facial expressions are generated using our own-developed rule-based state transition system. Facial expressions are further personalized for individuals by expression cloning. An avatar’s walking behavior is modeled using a skeleton model that is implemented by seven-motion sequences and finite state machines (FSMs). We discuss experimental results demonstrating the benefits of our approach.

시스템상태천이 샘플링을 이용한 변전소 신뢰도평가 컴퓨터 프로그램 개발

본 논문은 변전소 신뢰도 평가를 위하여 개발한 컴퓨터 프로그램을 소개하고 있다. 개발한 프로그램은 시스템상 태천이 샘플링(system state transition sampling)을 이용한 몬테카를로법을 근간으로 하고 있다. 시스템상태천이 샘플링은 평가 결과를 신속히 얻을 수 있지만, 평가 대상이 지수분포(exponential distribution)로 모형화된 경우에만 적용할 수 있다는 단점이 있다. 본 프로그램에서는 정전을 유발하는 사건간의 배타성을 가정함으로써 고장 수리 시간의 모형으로 비지수분포를 사용할 수 있도록 하였다. 개발한 프로그램을 신뢰도 평가결과가 잘 알려진 시스템에 적용하여 개발한 프로그램의 신뢰성을 증명하였다.