LOGICAL EMBEDDED PUSH-DOWN AUTOMATA IN TREE-ADJOINING GRAMMAR PARSING

This paper extends the "parsing as deduction" approach to tree-adjoining grammars by showing how a TAG recognition problem can be reduced to a Datalog deduction problem, and presents an SLD selection rule that makes the proof search correspond to a top-down parse using the original grammar. Just as in the DCG extension of context-free grammars, this approach permits nodes to be labeled with firsl-order terms (rather than only atomic symbols). Finally the paper discusses implementation matters, and describes how the control rule can be efficiently implemented in Prolog.     

反应系统的连续时序逻辑表示和验证

引进一个称为LTLC的连续时间时序逻辑,用来对反应系统进行规范与验证．LTLC的一个重要特点是它能在统一的逻辑框架下表示反应系统及其性质,这样就可将系统与性质问的满足关系转化为逻辑公式间的蕴涵关系．同时,采用非负实数集作为时间域还使我们可以利用标准的存在量词来表示变量隐藏,并可用逻辑蕴涵来表示反应系统间的求精关系．该文首先给出了LTLC的一个简单介绍,然后讨论了如何使用LTLC对反应系统进行表示与推理,最后证明了一个关于LTLC的可判定性结果．此结果可用于有穷状态反应系统的自动验证．     

Verifying Temporal Properties of Reactive Systems: A STeP Tutorial

We review a number of formal verification techniques supported by STeP, the Stanford Temporal Prover, describing how the tool can be used to verify properties of several versions of the Bakery Mutual exclusion algorithm for mutual exclusion. We verify the classic two-process algorithm and simple variants, as well as an atomic parameterized version. The methods used include deductive verification rules, verification diagrams, automatic invariant generation, and finite-state model checking and abstraction.     

Modeling Biological Systems in Stochastic Concurrent Constraint Programming

We present an application of stochastic Concurrent Constraint Programming (sCCP) for modeling biological systems. We provide a library of sCCP processes that can be used to describe straightforwardly biological networks. In the meanwhile, we show that sCCP proves to be a general and extensible framework, allowing to describe a wide class of dynamical behaviours and kinetic laws.     

Using Program Transformations to Provide Safety Properties for Real-Time Systems

The process of showing that a program satisfies some particular properties with respect to its specification is called program verification. Axiomatic semantics is a verification method that makes assertions describing properties about the states of a program. There exists a transformation from the assertions of a program's verification proof to executable assertions. The latter may be embedded in the program to make it fault tolerant. An axiomatic proof system for concurrent programs is applied to generate executable assertions in a real time distributed environment. A train set example is used as modelproblem.     

Model Checking Temporal Aspects of Inconsistent Concurrent Systems Based on Paraconsistent 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 paraconsistent temporal logic (QCTL) for supporting the verification of temporal properties of such systems even where the consistent model is not available. 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.     

Inducing Constructor Systems from Example-Terms by Detecting Syntactical Regularities

We present a technique for inducing functional programs from few, well chosen input/output-examples (I/O-examples). Potential applications for automatic program or algorithm induction are to enable end users to create their own simple programs, to assist professional programmers, or to automatically invent completely new and efficient algorithms. In our approach, functional programs are represented as constructor term rewriting systems (CSs) containing recursive rules. I/O-examples for a target function to be implemented are a set of pairs of terms (F(i_i),o_i) meaning that F(i_i)—denoting application of function F to input i_i—is rewritten to o_i by a CS implementing the function F. Induction is based on detecting syntactic regularities between example terms. In this paper we present theoretical results and describe an algorithm for inducing CSs over arbitrary signatures/data types which consist of one function defined by an arbitrary number of rules with an arbitrary number of non-nested recursive calls in each rule. Moreover, we present empirical results based on a prototypical implementation.     

多智能体系统中并发动态知识、信念和肯定性逻辑的研究

将知识、信念和肯定性逻辑从单个智能体扩展到多智能体系统,并且实现了多智能体系统中知识、信念和肯定性逻辑与具有并发动态属性的行为之间的很好结合.以此为基础,提出了多智能体系统中并发动态知识、信念和肯定性逻辑,简称CDKBC逻辑.为了对CDKBC逻辑进行解释,也给出了CDKBC模型,并且讨论了知识、信念和肯定性之间的关系,即知识蕴涵着肯定性,肯定性蕴涵着信念.文中也给出了一个相应的证明系统(即公理系统),证明了该系统是可靠的和完备的,并且证明了系统的有效性问题是EXPTIME完全的.最后论文给出了CDKBC逻辑的实例.     

Procedure-Level Verification of Real-time Concurrent Systems

We want to develop verification techniques for real-time concurrent system specifications with high-level behavior structures. This work identifies two common engineering guidelines respected in the development of real-world software projects, structured programming and local autonomy in concurrent systems, and experiments with special verification algorithm based on those engineering wisdoms. The algorithm we have adopted respects the integrity of program structures, treats each procedure as an entity instead of as a group of statements, allows local state space search to exploit the local autonomy in concurrent systems without calculating the Cartesian products of local state spaces, and derives from each procedure declaration characteristic information which can be utilized in the verification process anywhere the procedure is invoked. We have endeavored to implement our idea, test it against an abstract extension of a real-world protocol in a mobile communication environment, and report the data.     

Support for Implementation of Evolutionary Concurrent Systems

Concurrent programs that embed specifications of synchronizations in the body of their component are difficult to extend and modify. Small changes in a concurrent program, particularly changes in the interactions among components, may require re-implementation of a large number of components. Even specifications of components cannot be reused easily. This paper presents a concurrent program composition mechanism in which both specification and implementation of computations and interactions are completely separated. Separation of specifications and implementations facilitates extensions and modifications of programs by allowing one to separately change the implementations of computations and interactions. It also supports their reusability. The paper also describes the design and implementation of a concurrent object-oriented programming language based on this model, including a compiler for the language, and reports on the execution behavior of programs written in the language.     

Argumentation and the Dynamics of Warranted Beliefs in Changing Environments

One of the most difficult problems in Multi-Agent Systems (MAS) involves representing the knowledge and beliefs of an agent which performs its tasks in a dynamic environment. New perceptions modify this agent’s current knowledge about the world, and consequently its beliefs about it also change. Such a revision and update process should be performed efficiently by the agent, particularly in the context of real-time constraints. In the last decade argumentation has evolved as a successful approach to formalize defeasible, commonsense reasoning, gaining wide acceptance in the MAS community by providing tools for designing and implementing features, which characterize reasoning capabilities in rational agents. In this paper we present a new argument-based formalism specifically designed for representing knowledge and beliefs of agents in dynamic environments, called Observation-based Defeasible Logic Programming (ODeLP). A simple but effective perception mechanism allows an ODeLP-based agent to model new incoming perceptions, and modify the agent’s knowledge about the world accordingly. In addition, in order to improve the reactive capabilities of ODeLP-based agents, the process of computing beliefs in a changing environment is made computationally attractive by integrating a “dialectical database” with the agent’s program, providing pre-compiled information about previous inferences. We present algorithms for managing dialectical databases as well as examples of their use in the context of real-world problems.     

物联网系统的组合与验证

目前针对物联网的研究主要是对系统进行整体分析,设计与验证过程较复杂。为此,利用混成系统对物联网系统进行建模,将一个复杂的物联网系统拆分成若干个小的成员系统,分别验证每个成员系统的特性,并通过组合实现对整个物联网系统的验证。以智能交通系统为例进行分析,结果表明,该方法可降低系统分析和验证的复杂度,提高模块化程度,保证物联网系统的可扩展性。     

Declarative Bias for Specific-to-General ILP Systems

A comparative study is presented of language biases employed in specific-to-general learning systems within the Inductive Logic Programming (ILP) paradigm. More specifically, we focus on the biases employed in three well known systems: CLINT, GOLEM and ITOU, and evaluate both conceptually and empirically their strengths and weaknesses. The evaluation is carried out within the generic framework of the NINA system, in which bias is a parameter. Two different types of biases are considered: syntactic bias, which defines the set of well-formed clauses, and semantic bias, which imposes restrictions on the behaviour of hypotheses or clauses. NINA is also able to shift its bias (within a predefined series of biases), whenever its current bias is insufficient for finding complete and consistent concept definitions. Furthermore, a new formalism for specifying the syntactic bias of inductive logic programming systems is introduced.This paper extends the papers (Adé & Bruynooghe, 1992) and (Rouveirol et al., 1993).     

Decidability of infinite-state timed CCP processes and first-order LTL

The ntcc process calculus is a timed concurrent constraint programming (ccp) model equipped with a first-order linear-temporal logic (LTL) for expressing process specifications. A typical behavioral observation in ccp is the strongest postcondition (sp). The ntcc sp denotes the set of all infinite output sequences that a given process can exhibit. The verification problem is then whether the sequences in the sp of a given process satisfy a given ntcc LTL formula.

This paper presents new positive decidability results for timed ccp as well as for LTL. In particular, we shall prove that the following problems are decidable: (1) the sp equivalence for the so-called locally-independent ntcc fragment; unlike other fragments for which similar results have been published, this fragment can specify infinite-state systems, (2) verification for locally-independent processes and negation-free first-order formulae of the ntcc LTL, (3) implication for such formulae, (4) Satisfiability for a first-order fragment of Manna and Pnueli's LTL. The purpose of the last result is to illustrate the applicability of ccp to well-established formalisms for concurrency.     

Elimination of Local Variables from Definite Logic Programs

In logic programming, a variable is said to be local if it occurs in a clause body but not in its head atom. It is well-known that local variables are the main cause of inefficiency (sometimes even incompleteness) in negative goal computation. The problem is twofold. First, the negation of a clause body that contains a local variables is not expressible without universal quantification, whereas the abscence of local variables guarantees that universal quantification can be avoided to compute negation. Second, computation of universal quantification is an intrinsically difficult task. In this paper, we introduce an effective method that takes a definite logic program and transforms it into a local variable free (definite) program. Source and target programs are equivalent w.r.t. three-valued logical consequences of program completion. In further work, we plan to extend our results to normal logic programs.     

编程思维训练通用模型研究与实现

程序设计类课程是培养学生逻辑编程能力的基本课程之一,但目前普遍反映出学生对此类课程的学习兴趣不浓,对程序设计与实现的逻辑思维混乱不清,学习效果较差。如何脱离编程语言本身,运用模拟现实生活的思维训练模型来形象地展示编程的原理与逻辑流程,以提高学生对程序设计的逻辑思维能力和学习效果是本文研究的重点。