Unified verification and monitoring of executable UML specifications

Software and Systems Modeling - The increasing complexity of embedded systems renders software verification more complex, requiring monitoring and formal techniques, like model-checking. However,...     

Multi-agent system motion planning under temporal logic specifications and control barrier function

In this paper, we provide a novel scheme to solve the motion planning problem of multi-agent systems under high-level task specifications. First, linear temporal logic is applied to express the global task specification. Then an efficient and decentralized algorithm is proposed to decompose it into local tasks. Moreover, we use control barrier function to synthesize the local controller for each agent under the linear temporal logic motion plan with safety constraint. Finally, simulation results show the effectiveness and efficiency of our proposed scheme.     

Verifying temporal specifications of Java programs

Software Quality Journal - Many Java programs encode temporal behaviors in their source code, typically mixing three features provided by the Java language: (1) pausing the execution for a limited...     

Combining multiple matchers for a high security fingerprint verification system

Integration of various fingerprint matching algorithms is a viable method to improve the performance of a fingerprint verification system. Different fingerprint matching algorithms are often based on different representations of the input fingerprints and hence complement each other. We use the logistic transform to integrate the output scores from three different fingerprint matching algorithms. Experiments conducted on a large fingerprint database confirm the effectiveness of the proposed integration scheme.     

Constructive linear-time temporal logic: Proof systems and Kripke semantics

In this paper we study a version of constructive linear-time temporal logic (LTL) with the “next” temporal operator. The logic is originally due to Davies, who has shown that the proof system of the logic corresponds to a type system for binding-time analysis via the Curry-Howard isomorphism. However, he did not investigate the logic itself in detail; he has proved only that the logic augmented with negation and classical reasoning is equivalent to (the “next” fragment of) the standard formulation of classical linear-time temporal logic. We give natural deduction, sequent calculus and Hilbert-style proof systems for constructive LTL with conjunction, disjunction and falsehood, and show that the sequent calculus enjoys cut elimination. Moreover, we also consider Kripke semantics and prove soundness and completeness. One distinguishing feature of this logic is that distributivity of the “next” operator over disjunction “?(A∨B)⊃?A∨?B” is rejected in view of a type-theoretic interpretation.     

A transformation-based synthesis of temporal specifications

This paper is concerned with specifications expressed in propositional temporal logic with finite past extension. The variables of the specifications are partitioned into input variables, the value of which is determined by the environment, output variables, the value of which may be required by the environment, and internal variables. We present a method to synthesise temporal specifications, i.e. to rewrite them into a form from which a valuation for the output variables may be generated from the input values without backtracking. The transformed specification characterises the same set of input/output functions as the original specification, but in a more explicit way. A simple interpreter chooses the actual function to be used.This work was supported by SERC under project number GR/F/30123 (MetateM).     

Modular formal verification of specifications of concurrent systems

In this paper, we propose a bottom‐up approach for the verification of systems with modular structure: we prove that when the modules are composed in specific ways, the complete software system verifies a composition of the properties each component does. We focus on the process of upgrading systems with new functionalities, where the validity of old requirements needs to be ensured, but also an understanding of the new properties the upgraded system would enjoy is useful. In this work, we assume each component to be specified by a CCS process, and the properties to be expressed by selective mu‐calculus formulae. Copyright © 2007 John Wiley & Sons, Ltd.     

Soundness in verification of algebraic specifications with OBJ

The algebraic specification tools of the OBJ family have no notion of open terms or quantifiers. Nonetheless there are methods of proving universally quantified statements about specifications. These methods are examined and found to be unsound.     

Abstract Implementation of Algebraic Specifications in a Temporal Logic Language

A formal technique for incorporating two specification paradigms is presented,in which an algebraic specification is implemented by a set of abstract procedures specified in pre and post-condition style.The link between the two level specifications is provided via a translation from terms of algebraic specifications into temporal logic formulae representing abstract programs.In terms of translation,a criterion for an abstract implementation satisfying its specification is given,which allows one to check the consistency between the two levels of specifications.The abstract implementations can be refined into executable code by refining each abstract procedure in it.It is proved that the satisfication relation between a specification and its implementations is preserved by such refinement steps.     

Semantic constraint specification and verification of ebXML business process specifications

Electronic Business using eXtensible Markup Language (ebXML) Business Process Specification Schema (BPSS) supports the specification of the set of elements required to configure a runtime system in order to execute a set of ebXML business transactions. The BPSS is available in two stand-alone representations; a UML version and an XML version. Due to the limitations of UML notations and XML syntax, however, the current ebXML BPSS specification is insufficient to formally specify semantic constraints of modeling elements. In this study, we propose a classification scheme for BPSS semantic constraints, and describe how to represent those semantic constraints formally using Object Constraint Language. As a way to verify a particular Business Process Specification (BPS) with formal semantic constraint modeling, we suggest a rule-based approach to represent the formal semantic constraints, and describe a detail mechanism to apply the rule-based specified constraints to the BPS in a prototype implementation.     

Noise compensation in a person verification system using face and multiple speech features

In this paper, we demonstrate that use of a recently proposed feature set, termed Maximum Auto-Correlation Values, which utilizes information from the source part of the speech signal, significantly improves the robustness of a text independent identity verification system. We also propose an adaptive fusion technique for integration of audio and visual information in a multi-modal verification system. The proposed technique explicitly measures the quality of the speech signal, adjusting the amount of contribution of the speech modality to the final verification decision. Results on the VidTIMIT database indicate that the proposed approach outperforms existing adaptive and non-adaptive fusion techniques. For a wide range of audio SNRs, the performance of the multi-modal system utilizing the proposed technique is always found to be better than the performance of the face modality.     

Formal verification of OIL component specifications using mCRL2

International Journal on Software Tools for Technology Transfer - To aid in making software bug-free, several high-tech companies are moving from coding to modelling. In some cases model checking...     

Development of communication protocols using algebraic and temporal specifications

The paper pursues two main goals. First, an attempt is made to specify and verify protocols in a completely rigorous manner using the formalisms of temporal logic and algebraic specification. Second––and even more important––the protocol specifications are not presented as monolithic pieces of text, but rather are developed in a stepwise process, evolving from simple genotypes into the final complex products. This is illustrated with selected fragments of the TCP/IP protocol.     

An approach for machine-assisted verification of Timed CSP specifications

The real-time process calculus Timed CSP is capable of expressing properties such as deadlock-freedom and real-time constraints. It is therefore well-suited to model and verify embedded software. However, proofs about Timed CSP specifications are not ensured to be correct since comprehensive machine-assistance for Timed CSP is not yet available. In this paper, we present our formalization of Timed CSP in the Isabelle/HOL theorem prover, which we have formulated as an operational coalgebraic semantics together with bisimulation equivalences and coalgebraic invariants. This allows for semi-automated and mechanically checked proofs about Timed CSP specifications. Mechanically checked proofs enhance confidence in verification because corner cases cannot be overlooked. We additionally apply our formalization to an abstract specification with real-time constraints. This is the basis for our current work, in which we verify a simple real-time operating system deployed on a satellite. As this operating system has to cope with arbitrarily many threads, we use verification techniques from the area of parameterized systems for which we outline their formalization.     

Rule-base content verification using a digraph-based modelling approach

Ensuring that the content of a rule-base, which is being encoded, is free from problems of consistency, completeness, and conciseness, is necessary to avoid any performance errors that might occur during consultation sessions with the rule-based system. In this paper we have described, formally, content verification of a specific type of rule-base using a digraph-based modelling approach. Through analytic formulations it is demonstrated that problems in the rule-base lead to the existence of certain properties in the digraph and various rule-base model representations that have been devised in this work. These properties, in turn, as is also shown through an example, can be examined for rule-base content verification.     

Robustness of temporal logic specifications for continuous-time signals

In this paper, we consider the robust interpretation of Metric Temporal Logic (MTL) formulas over signals that take values in metric spaces. For such signals, which are generated by systems whose states are equipped with non-trivial metrics, for example continuous or hybrid, robustness is not only natural, but also a critical measure of system performance. Thus, we propose multi-valued semantics for MTL formulas, which capture not only the usual Boolean satisfiability of the formula, but also topological information regarding the distance, ε$\epsilon$, from unsatisfiability. We prove that any other signal that remains ε$\epsilon$-close to the initial one also satisfies the same MTL specification under the usual Boolean semantics. Finally, our framework is applied to the problem of testing formulas of two fragments of MTL, namely Metric Interval Temporal Logic (MITL) and closed Metric Temporal Logic (clMTL), over continuous-time signals using only discrete-time analysis. The motivating idea behind our approach is that if the continuous-time signal fulfills certain conditions and the discrete-time signal robustly satisfies the temporal logic specification, then the corresponding continuous-time signal should also satisfy the same temporal logic specification.