对象式逻辑程序设计语言LKO的说明性语义

本文基于逻辑程序设计语言的良基模型语义，探讨了对象逻辑程序设计语言ＬＫＯ的说明性语义，该语义由组合迭代的极小不动点定义，具有构造性和组合性，迷在ＬＫＯ中进一步引入非单调继承和逻辑奠定了基础。     

Heterogeneous knowledge representation: integrating connectionist and symbolic computation

Heterogeneous knowledge representation allows combination of several knowledge representation techniques. For instance, connectionist and symbolic systems are two different computational paradigms and knowledge representations. Unfortunately, the integration of different paradigms and knowledge representations is not easy and very often is informal. In this paper, we propose a formal approach to integrate these two paradigms where as a symbolic system we consider a (logic) rule-based system. The integration is operated at language level between neural networks and rule languages. The formal model that allows the integration is based on constraint logic programming and provides an integrated framework to represent and process heterogeneous knowledge. In order to achieve this we define a new language that allows expression and modelling in a natural and intuitive way the above issues together with the operational semantics.     

Asynchronous communication model based on linear logic

We propose a new framework called ACL for concurrent computation based on linear logic. ACL is a kind oflinear logic programming framework, where its operational semantics is described in terms ofproof construction in linear logic. We also give a model-theoretic semantics based onphase semantics, a model of linear logic. Our framework well captures concurrent computation based on asynchronous communication. It will, therefore, provide us with a new insight into other models of asynchronous concurrent computation from alogical point of view. We also expect ACL to become a formal framework for analysis, synthesis and transformation of concurrent programs by the use of techniques for traditional logic programming. ACL's attractive features for concurrent programming paradigms are also discussed.     

Modeling in the design of a KBS validation system

We describe and illustrate the modeling issues in the design of a system for validation of knowledge based systems (KBSs). the domain of such a validation system is “KBSs and their validation problems.” the basic idea in our solution is the following. Since different KBSs may use different knowledge representation languages, we first represent the target KBS (i.e., the KBS to be validated) in a general formal model of KBS, and then validate it in this form. the advantage of this strategy is that validation problem solving needs only to refer to the common language of the general formal model. We present a set of possible conceptual abstraction levels in such a model, and argue that each level is associated with a related view on validation problems. Since high level characterizations are difficult to abstract from current knowledge representation languages, we consider the formal aspects of modeling mainly at the “lowest” level, the so-called inference primitive level. We illustrate the approach by formalizing a solution for selected modeling issues at this level.     

A formal mathematical framework for modeling probabilistic hybrid systems

The development of autonomous agents, such as mobile robots and software agents, has generated considerable research in recent years. Robotic systems, which are usually built from a mixture of continuous (analog) and discrete (digital) components, are often referred to as hybrid dynamical systems. Traditional approaches to real-time hybrid systems usually define behaviors purely in terms of determinism or sometimes non-determinism. However, this is insufficient as real-time dynamical systems very often exhibit uncertain behavior. To address this issue, we develop a semantic model, Probabilistic Constraint Nets (PCN), for probabilistic hybrid systems. PCN captures the most general structure of dynamic systems, allowing systems with discrete and continuous time/variables, synchronous as well as asynchronous event structures and uncertain dynamics to be modeled in a unitary framework. Based on a formal mathematical paradigm exploiting abstract algebra, topology and measure theory, PCN provides a rigorous formal programming semantics for the design of hybrid real-time embedded systems exhibiting uncertainty.      

Knorc Calculus and Its Formal Semantics--To Honor my Friend Prof. Krieg-Brueckner''s 66th Birthday

This paper introduces the orchestration calculus Knorc, which is a conservative extension of the Orc calculus designed by J. Misra et. al. Orc is a simple but powerful calculus for wide area computing, whose simplicity makes it a solid kernel for orchestration programming. But on the other hand Orc leaves everything else to the programmer, which often makes the programming task complicated. The design idea of Knorc was to provide Orc with a delicately selected set of facilities to greatly increase the expressive power of the calculus and at the same time keep the calculus concise. The distinguished features of Knorc include, but not limited to: combination of process algebra and logic programming, site considered as remote Boolean procedure, Horn-like logic programming and inference, diversity of different parallelism mechanisms, network of abstract knowledge sources, open world assumption as opposed to closed world assumption where OWA means existing sites need not be known to the programmer, symmetric process-to-process communication, batch processing facilities of knowledge and data, as well as broad band message transmission. Besides introducing the general structures of the language Knorc, we present also a formal structural operational semantics. This is one of the major foci of this paper.     

A model for the formal definition of programming languages

An operational model which allows the complete formal definition of the full syntax and, particularly, semantics of programming languages is described. Both its syntactic and semantic parts are based on so-called linked-forest manipulation systems which allow the definition of mappings on forests. The idea of “linking” is crucial for the given model, we represent not only abstract programs but also intermediate states of our system (abstract computer) by labelled forests with pointers.     

Semantic Issues in the Verification of Agent Communication Languages

This article examines the issue of developing semantics for agent communication languages. In particular, it considers the problem of giving a verifiable semantics for such languages—a semantics where conformance (or otherwise) to the semantics could be determined by an independent observer. These problems are precisely defined in an abstract formal framework. Using this framework, a number of example agent communication frameworks are defined. A discussion is then presented, of the various options open to designers of agent communication languages, with respect the problem of verifying conformance.     

一个并发对象演算

由于缺乏一个为人们接受的描述并发对象系统语义的形式化模型,开发面向对象程序设计语言的开发受到了很大的制约,为了给并发面向对象程序设计定义一个公共的语义框架,人们分别以π演算和ａｃｔｏｒ模型为基础进行了研究。     

一种新的辩论推理模式及其应用

文中定义了一个新的辩论推理模式,建立了一个形式化的知识表示框架,并把它应用于研究扩展逻辑程序类的说明语义,结果表明,新语义克服了择优语义的不足。作者还根据上述研究结果实现了逻辑程序设计风格下的知识框架。     

A declarative coordination language

We describe Gammalog, a logic language whose semantics is based on the chemical metaphor. The language combines the ability of describing coordination by transformation rules on a shared-dataspace, as in Gamma, with the execution model of logic programming. The main feature of Gammalog is that the declarative reading of programs is not restricted to the pure logic language but it also includes the coordination mechanisms. This feature makes Gammalog a promising alternative to other coordination models which can be embedded in logic programming. We present the language syntax, its formal semantics, and a prototype implementation based on Gödel, which inherits its strongly typed framework. As an example of the expressive power of the language we provide the specification of a simple operating system.     

高性能知识库构造环境

知识库系统(KBS)开发环境的特点是简便性和领域适应性。我们认为如果在KBS开发环境中既有抽象结均,又有多种集成工具,则该环境将会非常有效。本文介绍一个KBS 开发环境DECISION-E,它有一个适应应用领域KBS 的清晰、灵活的抽象结构,而且还有许多集成工具。这种结构使得DECISION-E能建立多种现实领域中的KBS,并使建立的KBS能较全面地反映应用领域的性质。集成工具将辅助设计者建立KBS,支持KBS 的问题求解并进行多种事务处理。在DECISIGN-E 中还采用了下面的一些特殊技术:不同层次的知识表达方法,多推理机,推理中断处理,基于全局黑板的分布式问题求解,基于知识的建模及数据抽象,演绎数据库管理方法。     

Smalltalk—80的基本概念和抽象文法

Smalltalk—80是原型的面向对象程序设计语言和环境,其中所体现的面向对象方法学已广泛应用于计算机科学的各个领域。我们已经完成除进程之外的所有Smalltalk成份的指称语义描述。作为系列文章的首篇,本文简要介绍Smalltalk的基本概念,并给出其完整的抽象文法,从而为准确地理解Smalltalk,正确地描述其形式语义奠定良好的基础。     

A Fully Abstract Semantics for Concurrent Constraint Programming

A compositional and fully abstract semantics for concurrent constraint programming is developed. It is the first fully abstract semantics which takes into account both non-determinism, infinite computations, and fairness. We present a simple concurrent constraint programming language, whose semantics is given by a set of reduction rules augmented with fairness requirements. In the fully abstract semantics we consider two aspects of a trace, viz. the function computed by the trace (the functionality) and the set of input and output data (the limit of the trace). We then derive the fully abstract semantics from the set of traces using a closure operation. We give two proofs of full abstraction; the first relies on the use of a syntactically infinite context. The second proof requires only a finite context, but assumes as input a representation of the function to be computed by the context. Finally, we examine the algebraic properties of the programming language with respect to the fully abstract semantics. It turns out that the non-deterministic selection operation can be defined using operations derived from parallel composition and the usual set-theoretic operations on sets of traces.     

面向方面程序的静态语义研究

针对面向方面程序,许多研究者已定义了各种各样的形式语义。但是这些语义都不能够全面、准确地对面向方面程序的规范和方面声明部分进行描述。针对该问题,首先定义一种统一的面向方面程序的规范语言;其次对面向方面程序中的连接点和切点这两个重要概念进行形式化定义;再次引入结构变量表示面向方面程序的基本结构;最后应用统一程序理论中的设计定义面向方面的静态语义,并对其可靠性进行证明。同时,用一个例子说明该语义的使用。