Yixiang Chen

A Metric Model for Trustworthiness of Softwares

Trustworthiness of softwares describes the behavior of a software when it finishes its required task. The goal of this paper is to establish a metric model which measures the trustworthiness of a software based on the basic attributes of softwares. These attributes are classified into two classes: critical and non-critical attributes and four trust criteria of monotonicity, acceleration, sensitivity and substitutivity are proposed. A metric model of trustworthiness which satisfies these four criteria is introduced.

A new metric model for trustworthiness of softwares

As people depend more and more on softwares, there has been an increasing demand for the trustworthiness of the software. To measure the trustworthiness of software, we need to design appropriate trustworthy metrics. We once proposed four metric criteria for the multi-dimensional trustworthiness of the software and a metric model which satisfies these four criteria. In this paper, we describe a new metric model for the trustworthiness of the software which satisfies almost all these four criteria. Compared with the previous model, this model is better in the view of substitutivity. We also give a polynomial-time combinational algorithm for estimating the weight vectors appeared in the model based on the priority methods.

Simulation for lattice-valued doubly labeled transition systems

During the last decades, a large amount of multi-valued transition systems, whose transitions or states are labeled with specific weights, have been proposed to analyze quantitative behaviors of reactive systems. To set up a unified framework to model and analyze systems with quantitative information, in this paper, we present an extension of doubly labeled transition systems in the framework of residuated lattices, which we will refer to as lattice-valued doubly labeled transition systems (LDLTSs). Our model can be specialized to fuzzy automata over complete residuated lattices, fuzzy transition systems, and multi-valued Kripke structures. In contrast to the traditional yes/no approach to similarity, we then introduce lattice-valued similarity between LDLTSs to measure the degree of closeness of two systems, which is a value from a residuated lattice. Further, we explore the properties of robustness and compositionality of the lattice-valued similarity. Finally, we extend the Hennessy-Milner logic to the residuate lattice-valued setting and show that the obtained logic is adequate and expressive with lattice-valued similarity.

On Denotational Semantics of Spatial-Temporal Consistency Language -- STeC

In order to describe the requirement of spatial and temporal consistency of cyber-physical systems, a specification language called as STeC was proposed by Chen in [1]. In this paper, we focus on the theory of semantics of STeC. After simply restating the syntax and operational semantics, we mainly establish the denotational semantics of STeC. To investigate the reasonability of the denotational semantics, an abstract theorem is given to show the soundness and completeness of the denotational semantics. Finally, a simple case about China Gaotie (which means High-speed train) is given to show how to compute the operational and denotational semantics.

Quantitative Analysis of Lattice-valued Kripke Structures

To model and analyze systems with multi-valued information, in this paper, we present an extension of Kripke structures in the framework of complete residuted lattices, which we will refer to as lattice-valued Kripke structures (LKSs). We then show how the traditional trace containment and equivalence relations, can be lifted to the lattice-valued setting, and we introduce two families of lattice-valued versions of the relations. Further, we explore some interesting properties of these relations. Finally, we provide logical characterizations of our relations by a natural extension of linear temporal logic.

A New Metric Model for Trustworthiness of Softwares

As people depend more and more on softwares, there has been an increasing demand for the trustworthiness of the software. To measure the trustworthiness of software, we need to design appropriate trustworthy metrics. We once proposed four metric criteria for the multi-dimensional trustworthiness of the software and a metric model which satisfies these four criteria. In this paper, we describe a new metric model for the trustworthiness of the software which satisfies almost all these four criteria. Compared with the previous model, this model is better in the view of substitutivity. We also give a polynomial-time combinational algorithm for estimating the weight vectors appeared in the model based on the priority methods.

Average Transitive Trustworthy Degrees for Trustworthy Networks

The goal of this paper is to investigate measurement models of transitive trustworthiness for trustworthy networks. The reals in the interval [0,1] are used to define trust degrees in such a way that the larger its trust degree and the more it is trustworthy. A basic contribution is to introduce the average algorithm for the measurement of the transitive trustworthiness along a path in a weighted digraph. Due to the NP-hardness of the average algorithm for finding simple paths with the maximal average transitive trust degree, we propose the modified matrix operation to compute maximal average transitive trustworthy degrees of paths. This computation is polynomial, but might produce non-simple paths. A simple simulation is also given.

A logical approach to stable domains

Building on earlier work by Guo-Qiang Zhang on disjunctive information systems, and by Thomas Ehrhard, Pasquale Malacaria, and the first author on stable Stone duality, we develop a framework of disjunctive propositional logic in which theories correspond to algebraic L-domains. Disjunctions in the logic can be indexed by arbitrary sets (as in geometric logic) but must be provably disjoint. This raises several technical issues which have to be addressed before clean notions of axiom system and theory can be defined. We show soundness and completeness of the proof system with respect to distributive disjunctive semilattices, and prove that every such semilattice arises as the Lindenbaum algebra of a disjunctive theory. Via stable Stone duality, we show how to use disjunctive propositional logic for a logical description of algebraic L-domains.

Modeling and Verification of Space-Air-Ground Integrated Networks on Requirement Level Using STeC

This paper introduces a domain Spatio-Temporal Consistency (STeC) language for the application domain of space-air-ground integrated networks. The STeC language is taken as the foundation of modeling our systems, bacause it works well on specifying real-time systems concerning not only the time characteristic but also the location characteristic and the consistency between them. In this paper, a domain-STeC language is devised and applied to model satellite observation processes. We use two tools to check and verify this STeC model, the syntax and spatio-temporal consistency were checked in STeC tool, and after being transformed into timed automata model, some further verification can be finished in UPPAAL tool. It shows that the instantiated STeC approach is suitable for modeling and verifying space-air-ground integrated networks on the requirement level. This work helps to ensure the spatial-temporal consistency in that application domain, and increases the reliability and dependability of our system.

Timed Automata Semantics of Spatial-Temporal Consistency Language STeC

Intelligent Transportation Systems (ITS) are a class of quickly evolving modern safety-critical embedded systems. Dealing with their growing complexity demands a high-level formal modeling language along with adequate verification techniques. STeC has recently been introduced as a process algebra that deals natively with both spatial and temporal properties. Even though STeC has the right expressive power, it does not provide a direct tooled support for verification. We propose to encode STeC specifications as Timed Automata to provide such a support and we illustrate our transformation strategy on a simple example.