A survey on temporal logics for specifying and verifying real-time systems

Over the last two decades, there has been an extensive study of logical formalisms on specifying and verifying real-time systems. Temporal logics have been an important research subject within this direction. Although numerous logics have been introduced for formal specification of real-time and complex systems, an up to date survey of these logics does not exist in the literature. In this paper we analyse various temporal formalisms introduced for specification, including propositional/first-order linear temporal logics, branching temporal logics, interval temporal logics, real-time temporal logics and probabilistic temporal logics. We give decidability, axiomatizability, expressiveness, model checking results for each logic analysed. We also provide a comparison of features of the temporal logics discussed.

Hierarchical Controller Synthesis Under Linear Temporal Logic Specifications Using Dynamic Quantization

Linear temporal logic(LTL)is an intuitive and expressive language to specify complex control tasks,and how to design an efficient control strategy for LTL specification is still a challenge.In this paper,we implement the dynamic quantization technique to propose a novel hierarchical control strategy for nonlinear control systems under LTL specifications.Based on the regions of interest involved in the LTL formula,an accepting path is derived first to provide a high-level solution for the controller synthesis problem.Second,we develop a dynamic quantization based approach to verify the realization of the accepting path.The realization verification results in the necessity of the controller design and a sequence of quantization regions for the controller design.Third,the techniques of dynamic quantization and abstraction-based control are combined together to establish the local-to-global control strategy.Both abstraction construction and controller design are local and dynamic,thereby resulting in the potential reduction of the computational complexity.Since each quantization region can be considered locally and individually,the proposed hierarchical mechanism is more efficient and can solve much larger problems than many existing methods.Finally,the proposed control strategy is illustrated via two examples from the path planning and tracking problems of mobile robots.

Completeness of bounded model checking temporal logic of knowledge

In order to find the completeness threshold which offers a practical method of making bounded model checking complete, the over-approximation for the complete threshold is presented. First, a linear logic of knowledge is introduced into the past tense operator, and then a new temporal epistemic logic LTLKP is obtained, so that LTLKP can naturally and precisely describe the system＇s reliability. Secondly, a set of prior algorithms are designed to calculate the maximal reachable depth and the length of the longest of loop free paths in the structure based on the graph structure theory. Finally, some theorems are proposed to show how to approximate the complete threshold with the diameter and recurrence diameter. The proposed work resolves the completeness threshold problem so that the completeness of bounded model checking can be guaranteed.

Intrusion Detection Algorithm Based on Model Checking Interval Temporal Logic

Model checking based on linear temporal logic reduces the false negative rate of misuse detection.However,linear temporal logic formulae cannot be used to describe concurrent attacks and piecewise attacks.So there is still a high rate of false negatives in detecting these complex attack patterns.To solve this problem,we use interval temporal logic formulae to describe concurrent attacks and piecewise attacks.On this basis,we formalize a novel algorithm for intrusion detection based on model checking interval temporal logic.Compared with the method based on model checking linear temporal logic,the new algorithm can find unknown succinct attacks.The simulation results show that the new method can effectively reduce the false negative rate of concurrent attacks and piecewise attacks.

Translating Linear Temporal Logic Formula s into Automata

To combat the well-known state-space explosion problem in Prop ositional Linear T emp o- ral Logic （PLTL） model checking, a novel algo- rithm capable of translating PLTL formulas into Nondeterministic Automata （NA） in an efficient way is proposed. The algorithm firstly transforms PLTL formulas into their non-free forms, then it further translates the non-free formulas into their Normal Forms （NFs）, next constructs Normal Form Graphs （NFGs） for NF formulas, and it fi- nally transforms NFGs into the NA which ac- cepts both finite words and int-mite words. The experimental data show that the new algorithm re- duces the average number of nodes of target NA for a benchmark formula set and selected formulas in the literature, respectively. These results indi- cate that the PLTL model checking technique em- ploying the new algorithm generates a smaller state space in verification of concurrent systems.

A Heuristic Method for Temporal Analysis Based on Petri Net

Reachability-based analysis and temporal analysis are used to verify the properties of concurrent systems, and it is important to exploit fast and efficient methods. This paper gives semantics of temporal formulae with edges of the transition system of Petri net, and then presents a fast temporal analyzing method, which takes advantage of both Petri net and temporal logic. The method only expands a path of equivalence trace while the path does not satisfy a property according to trace semantics of Petri net, and can validate directly the property on Petri net. Moreover, we exploit a minimal degree of in-out of a node as heuristics to select a path of an equivalence trace. Finally, we demonstrate the validity of the method that decreases state spaces and improves the verification system with the experimental results.

Timed automata for metric interval temporal logic formulae in prototype verification system

Based on analysis of the syntax structure and semantics model of the metric interval temporal logic （MITL） formulas, it is shown how to transform a formula written in the real-time temporal logic MITL formula into a fair timed automaton （TA） that recognizes its satisfying models with prototype verification system （PVS） in this paper. Both the tabular construction＇s principles and the PVS implementation details are given for the different type of MITL formula according to the corresponding semantics interpretations. After this transformation procedure, specifications expressed with MITL formula can be verified formally in the timed automata framework developed previously.

Model Checking over Paraconsistent Temporal Logic

Classical logic cannot be used to effectively reason about concurrent systems with inconsistencies (inconsistencies often occur, especially in the early stage of the development, when large and complex concurrent systems are developed). In this paper, we propose the use of a guasi-classical temporal logic (QCTL) for supporting the verification of temporal properties of such systems even where the consistent model is not available. Our models are paraKripke structures (extended standard Kripke structures), in which both a formula and its negation are satisfied in a same state, and properties to be verified are expressed by QCTL with paraKripke structures semantics. We introduce a novel notion of paraKripke models, which grasps the paraconsistent character of the entailment relation of QCTL. Furthermore, we explore the methodology of model checking over QCTL, and describe the detailed algorithm of implementing QCTL model checker. In the sequel, a simple example is presented, showing how to exploit the proposed model checking technique to verify the temporal properties of inconsistent concurrent systems.

基于用户同意的隐私保护协议形式化描述与验证

将用户同意与访问控制相结合是解决隐私保护的主要方法之一.然而,现有的隐私保护访问控制方法仅从数据控制者的角度,不考虑个人对访问决策的参与,无法满足自主可控的需求.为了解决这个问题,本文提出了一种基于用户同意的隐私保护访问控制协议,将用户同意转化为一种同意权限,形成一种同意加授权的双重访问控制机制.本文给出协议的语法、语义及安全性定义和分析,并采用模型检测的方法对协议应满足的性质进行验证,最终证明本文的设计可以从访问控制的角度满足个人信息保护法规的要求.

Approach to adaptive service matchmaking

To make service matchmaking more adaptive to various service requests and diverse web services, an adaptive approach-ASMA is proposed to service matchmaking based on temporal logic model-checking. The approach is based on the proposed abstract service model, ASM-TL, which addresses some important constraints for identifying capabilities of web services, such as service inner constraints and invocation constraints, and also has a virtual process model for describing service behavioral properties. By treating service requests as temporal logic conditions and web services as temporal models, ASMA does service matchmaking through model checking. Therefore, ASMA makes service matchmaking more accurate and more adaptive to the variety of service requests and the diversity of web services. The approach has been applied to the problem solving environment （PSE） for bioinformatics research. Applications show that the approach is suitable for dynamic environments.

An Intrusion Detection Algorithm for Wireless Networks Based on ASDL

Wireless networks are more vulnerable to cyberattacks than cable networks. Compared with the misuse intrusion detection techniques based on pattern matching, the techniques based on model checking(MC) have a series of comparative advantages. However, the temporal logics employed in the existing latter techniques cannot express conveniently the complex attacks with synchronization phenomenon. To address this problem, we formalize a novel temporal logic language called attack signature description language(ASDL). On the basis of it, we put forward an ASDL model checking algorithm. Furthermore, we use ASDL programs, which can be considered as temporal logic formulas,to describe attack signatures, and employ other ASDL programs to create an audit log. As a result, the ASDL model checking algorithm can be presented for automatically verifying whether or not the latter programs satisfy the formulas, that is, whether or not the audit log coincides with the attack signatures. Thus,an intrusion detection algorithm based on ASDL is obtained. The case studies and simulations show that the new method can find coordinated chop-chop attacks.

Model Checking Electronic CommerceSecurity Protocols Based on CTL

We present a model based on Computational Temporal Logic (CTL) methods forverifying security requirements of electronic commerce, protocols. The model describes formally theauthentication, confidentiality integrity, non-repudiation) denial of serviee and access control ofthe e-lectronic commerce protocols. We illustrate as case study a variant of the Lu-Smolka protocolproposed by Lu-Smolka Moreover, we have discovered two attacks that allow a dishonest user topurchase a good debiting the amountto another user. And also, we compared our work with relativeresearch works and found lhat the formal way of this paper is more general to specify securityprotocols for E-Commerce.

Modeling and Analysis of Data Dependencies in Business Process for Data-Intensive Services

With the growing popularity of data-intensive services on the Internet, the traditional process-centric model for business process meets challenges due to the lack of abilities to describe data semantics and dependencies, resulting in the inflexibility of the design and implement for the processes. This paper proposes a novel data-aware business process model which is able to describe both explicit control flow and implicit data flow. Data model with dependencies which are formulated by Linear-time Temporal Logic(LTL) is presented, and their satisfiability is validated by an automaton-based model checking algorithm. Data dependencies are fully considered in modeling phase, which helps to improve the efficiency and reliability of programming during developing phase. Finally, a prototype system based on j BPM for data-aware workflow is designed using such model, and has been deployed to Beijing Kingfore heating management system to validate the flexibility, efficacy and convenience of our approach for massive coding and large-scale system management in reality.

Formal Reduction of Interfaces to Large-scale Process Control Systems

A formal methodology is proposed to reduce the amount of information displayed to remote human operators at interfaces to large-scale process control plants of a certain type. The reduction proceeds in two stages. In the first stage, minimal reduced subsets of components, which give full information about the state of the whole system, are generated by determining functional dependencies between components. This is achieved by using a temporal logic proof obligation to check whether the state of all components can be inferred from the state of components in a subset in specified situations that the human operator needs to detect, with respect to a finite state machine model of the system and other human operator behavior. Generation of reduced subsets is automated with the help of a temporal logic model checker. The second stage determines the interconnections between components to be displayed in the reduced system so that the natural overall graphical structure of the system is maintained. A formal definition of an aesthetic for the required subgraph of a graph representation of the full system, containing the reduced subset of components, is given for this purpose. The methodology is demonstrated by a case study.

Autonomous Evolutionary Information Systems

Traditional information systems are passive, i.e., data or knowledge is created, retrieved, modified, updated, and deleted only in response to operations issued by users or application programs, and the systems only can execute queries or transactions explicitly submitted by users or application programs but have no ability to do something actively by themselves. Unlike a traditional information system serving just as a storehouse of data or knowledge and working passively according to queries or transactions explicitly issued by users and application programs, an autonomous evolutionary information system serves as an autonomous and evolutionary partner of its users that discovers new knowledge from its database or knowledge base autonomously, cooperates with its users in solving problems actively by providing the users with advices, and has a certain mechanism to improve its own state of “knowing” and ability of “working”. This paper seminally defines what is an autonomous evolutionary information system, explain why autonomous evolutionary information systems are needed, and presents some new issues, fundamental considerations, and research directions in design and development of autonomous evolutionary information systems.

Application of the Constrained Predicated Nets and Interval Logic to Production Systems

A method to model and analyze the hybrid systems is presented. The time to be considered in the plant is taken as an explicit parameter through the constrained predicated net (CPN). The CPN's basic structure is a Petri net with predicated transition. All components of the net are expressed by annotation which is defined on rational set Q. The analysis method for the plant is interval temporal logic represented by Petri nets. This paper combines the above two methods to synthesize the hybrid system, gives a simple and clear expression of the expected action of the studied plant.

Programming with Conditionals: Epistemic Programming for Scientific Discovery

In order to provide scientists with a computational methodology and some computational tools to program their epistemic processes in scientific discovery, we are establishing a novel programming paradigm, named ‘Epistemic Programming’, which regards conditionals as the subject of computing, takes primary epistemic operations as basic operations of computing, and regards epistemic processes as the subject of programming. This paper presents our fundamental observations and assumptions on scientific discovery processes and their automation, research problems on modeling, automating, and programming epistemic processes, and an outline of our research project of Epistemic Programming.

A Framed Temporal Logic Programming Language

We discuss the projection temporal logic (PTL), based on a primitiveprojection operator, prj. A framing technique is also presented, using which a synchronizationoperator, await, is defined within the underlying logic. A framed temporal logic programminglanguage (FTLL) is presented. To illustrate how to use both the language and framing technique, someexamples are given.

A complete coalition logic of temporal knowledge for multi-agent systems

Coalition logic （CL） is one of the most influential logical formalisms for strategic abilities of multi-agent systems. CL can specify what a group of agents can achieve through choices of their actions, denoted by [C]φ to state that a group of agents C can have a strategy to bring about φ by collective actions, no matter what the other agents do. However, CL lacks the temporal dimension and thus can not capture the dynamic aspects of a system. Therefore, CL can not formalize the evolvement of rational mental attitudes of the agents such as knowledge, which has been shown to be very useful in specifications and verifications of distributed systems, and has received substantial amount of studies. In this paper, we introduce coalition logic of temporal knowledge （CLTK）, by incorporating a temporal logic of knowledge （Halpern and Vardi＇s logic of CKLn） into CL to equip CL with the power to formalize how agents＇ knowledge （individual or group knowledge） evolves over the time by coalitional forces and the temporal properties of strategic abilities as well. Furthermore, we provide an axiomatic system for CLTK and prove that it is sound and complete, along with the complexity of the satisfiability problem which is shown to be EXPTIME-complete.

A temporal programming model with atomic blocks based on projection temporal logic

Atomic blocks, a high-level language construct that allows programmers to explicitly specify the atomicity of operations without worrying about the implementations, are a promising approach that simplifies concurrent programming. On the other hand, temporal logic is a successful model in logic programming and concurrency verification, but none of existing temporal programming models supports concurrent programming with atomic blocks yet. In this paper, we propose a temporal programming model （αPTL） which extends the projection temporal logic （PTL） to support concurrent programming with atomic blocks. The novel construct that formulates atomic execution of code blocks, which we call atomic interval formulas, is always interpreted over two consecutive states, with the internal states of the block being abstracted away. We show that the framing mechanism in projection temporal logic also works in the new model, which consequently supports our development of an executive language. The language supports concurrency by introducing a loose interleaving semantics which tracks only the mutual exclusion between atomic blocks. We demonstrate the usage of αPTL by modeling and verifying both the fine-grained and coarse-grained concurrency.