进程创建的语义及等价性

针对一个基于共享变量的带有进程创建的命令式语言,用变迁系统描述了它的结构操作语义,并用扩展的状态变迁迹模型定义了它的指称语义,在该模型下,状态变迁被区分为两种不同形式,分别表示发生在原进程和被创建进程中的状态变迁,这样便可以定义适当的语义复合运算,在对命令的指称进行复合时根据变迁类型的不同对变迁迹进行串行或交错连接,恰当地反映了进程的并发运行受创建命令在程序中的相对位置的限制,最后证明了这两个语义     

基于H-等价的算法识别技术研究

蕴涵在程序代码中的语义是程序语言词法和语法的抽象表达,构成了人脑思维与机器思维交互过程的中间变换。从指称语义出发,结合具体语言,用形式化的方法讨论了语义等价和H-等价(Herbrand等价)。H-等价的判定条件相对来说更容易得到满足,具有更广泛的可用性。结合具体算法给出了H-等价在算法识别方面的应用成果及其局限性。     

具有动作细化的实时并发进程的基于事件的操作语义以及一致性结果

对于包含动作精化的实时进程代数，人们已经为它定义了指称真并发语义。在这种语义里，动作精化被看作是一个操作符。人们自然会有这样的疑问：既然已经定义了指称真并发语义，为什么还要定义操作语义?这个问题可以从以下两个方面回答：首先，对于不带时间变量和动作精化操作的进程，为它赋予一个“标准”语义的含义就是指为它定义一个操作语义。定义操作语义常用的方法是定义一个具有标记的传递系统，它是由一些推理规则组成的集合，这些推理规则刻画了实际程序或系统     

算法语言L的指称语义

文中为算法语言Ｌ定义了动态指称语义，在描述中避免了含有函数空间构造运算的递归论域方程．指称语义可以说明Ｌ的一些良好的数学性质，也可以说明指称语义技术可以达到更好的直观性和实用性．     

语义转换--直接指称语义到接续指称语义

指称语义分为直接指称语义和接续指称语义，其中后一种语义描述的难度较大，给出了直接指称语义描述到接续指称语义描述的转换方法，这就使得这种语义转换的自动化成为可能．转换算法揭示了直接指称语义与接续指称语义之间的内在关系，同时也提供了写接续指称语义描述的有效方法．当需要检验同一种语言的直接指称语义描述和接续指称语义描述是否等价时，提供的技术是很有用的。     

CCD语义知识库的构造研究

CCD（the Chinese Concept Dictionary）是一个WordNet框架下的汉英双语语义知识库（the Chinese—English WordNet）．在制定语义规范后，作者提出了构造CCD的演化模型（the model of evolution）．新的构造模型强调双语语义知识库构造中的继承（inheritance）和转换（transformation）思想，希望从WordNet现有的英语单语语义信息出发，通过词典编纂者的联机翻译（online translations）和可视化操作（visualized operations）．逐步实现由WordNet到CCD的计算性转换，自然地得到一个双语语义知识库，从而大幅度提高构造此类语义知识库的效率和质量．针对该构造模型，作者设计并实现了可视化的辅助词典构造软件VACOL．该软件在北大计算语言所CCD项目中得到大规模的应用，取得了很好的成果．     

基于轨迹的程序语义之一：轨迹与语义对象

本文提出一种基于轨迹的指称语义框架,该框架结合了操作语义和代数语义的特征,避免使用专门的数学理论,将静态语义和动态语义结合在一起统一处理.本文及其续篇将通过一个中等规模的过程式模型语言来说明上述语义框架更适合描述真正的程序设计语言.本文首先引入轨迹概念和模型语言,然后讨论该语言的各句法成分所对应的语义论域,其中没有使用含有函数空间构造运算的递归论域方程.     

命令式模糊程序语言的语义

文中关注计算机语言的形式语义学,旨在建立一种命令式模糊程序语言的指称语义与最弱(线性)前置条件语义.首先,借助模糊逻辑中的三角模、三角余模、非、蕴含以及模糊关系的合成等成功地完成了这两种语义的建模.这种方法为形式语义学的研究提供了一个新的视角.其次,证明了该语言的一些重要性质并讨论了最弱前置条件语义与最弱线性前置条件语义之间的关系.最后,证明了指称语义与最弱(线性)前置条件语义之间的对偶,该对偶表明了这两种语义可以相互诱导.     

算法语言L的指称定义

文中为算法语言Ｌ定义了动态指称语义，在描述避免了含有函数空间构造运算的递归论域方程，指称语义可以说明Ｌ的一些良好的数学性质，也可以说明指称语义技术可以达以更好的直以性和实用性。     

函数式面向对象语言FOPL的指称语义

函数式面向对象程序设计语言ＦＯＰＬ是笔者设计并实现的一种合成语言，本文在一个全称的抽象域上描述了ＦＯＰＬ语言的指称语义。     

A comparative study of two formal semantics of the SIGNAL language

SIGNAL is a part of the synchronous languages family, which are broadly used in the design of safety-critical real-time systems such as avionics, space systems, and nuclear power plants. There exist several semantics for SIGNAL, such as denotational semantics based on traces (called trace semantics), denotational semantics based on tags (called tagged model semantics), operational semantics presented by structural style through an inductive definition of the set of possible transitions, operational semantics defined by synchronous transition systems (STS), etc. However, there is little research about the equivalence between these semantics. In this work, we would like to prove the equivalence between the trace semantics and the tagged model semantics, to get a determined and precise semantics of the SIGNAL language. These two semantics have several different definitions respectively, we select appropriate ones and mechanize them in the Coq platform, the Coq expressions of the abstract syntax of SIGNAL and the two semantics domains, i.e., the trace model and the tagged model, are also given. The distance between these two semantics discourages a direct proof of equivalence. Instead, we transformthem to an intermediate model, which mixes the features of both the trace semantics and the tagged model semantics. Finally, we get a determined and precise semantics of SIGNAL.     

Algebraic approach to linking the semantics of web services

Web services have become more and more important in these years, and BPEL4WS (BPEL) is a de facto standard for the web service composition and orchestration. It contains several distinct features, including the scope-based compensation and fault handling mechanism. We have considered the operational semantics and denotational semantics for BPEL, where a set of algebraic laws can be achieved via these two models, respectively. In this paper, we consider the inverse work, deriving the operational semantics and denotational semantics from algebraic semantics for BPEL. In our model, we introduce four types of typical programs, by which every program can be expressed as the summation of these four types. Based on the algebraic semantics, the strategy for deriving the operational semantics is provided and a transition system is derived by strict proof. This can be considered as the soundness exploration for the operational semantics based on the algebraic semantics. Further, the equivalence between the derivation strategy and the derived transition system is explored, which can be considered as the completeness of the operational semantics. Finally, the derivation of the denotational semantics from algebraic semantics is explored, which can support to reason about more program properties easily.     

Life-cycle of a dual object-oriented specification model for real-time systems

Dual approaches for real-time systems specification try to integrate in a unique model/language the most interesting features of both operational and denotational approaches. In some cases, the object-oriented paradigm has been used for integrating the above aspects and as a support for covering with a uniform approach the development life-cycle from requirements analysis to application coding, by presenting initially a mainly denotational semantics which changes in operational semantics with the increase of implementation details. For these reasons, traditional development life-cycles are unsuitable, and more specific phases are needed to exploit the potentiality of the approach. In this paper, the authors present the life-cycle defined for a dual approach proposed in the literature—i.e., TOOMS/TROL.     

Semantic theories of programs with nested interrupts

In the design of dependable software for embedded and real-time operating systems, time analysis is a crucial but extremely difficult issue, the challenge of which is exacerbated due to the randomness and nondeterminism of interrupt handling behaviors. Thus research into a theory that integrates interrupt behaviors and time analysis seems to be important and challenging. In this paper, we present a programming language to describe programs with interrupts that is comprised of two essential parts: main program and interrupt handling programs. We also explore a timed operational semantics and a denotational semantics to specify the meanings of our language. Furthermore, a strategy of deriving denotational semantics from the timed operational semantics is provided to demonstrate the soundness of our operational semantics by showing the consistency between the derived denotational semantics and the original denotational semantics.     

The semantics of the combination of atomized statements and parallel choice

In this paper we define a uniform language that is an extension of the language underlying the process algebraPA. One of the main extensions of this language overPA is given by so-called atomizing brackets. If we place these brackets around a statement then we treat this statement as an atomic action. Put differently, these brackets remove all interleaving points. We present a transition system for the language and derive its operational semantics. We show that there are several options for defining a transition system such that the resulting operational semantics is a conservative extension of the semantics forPA. We define a semantic domain and a denotational model for the language. Next we define a closure operator on the semantic domain and show how to use this closure operator to derive a fully abstract denotational semantics. Then the algebraic theory of the language is considered. We define a collection of axioms and a term rewrite system based on these axioms. Using this term rewrite system we are able to identify normal forms for the language. It is shown that these axioms capture the denotational equality. It follows that if two terms are provably equal then they have the same operational semantics. Finally, we show how to extend the axiomatization in order to axiomatize its operational equivalence.     

Semantics of plan revision in intelligent agents

In this paper, we give an operational and denotational semantics for a meta-language of the 3APL agent programming language. With this meta-language, various 3APL interpreters can be programmed. We prove equivalence of the operational and denotational semantics. Furthermore, we give an operational semantics for object-level 3APL. Using this semantics, we relate the 3APL meta-language to object-level 3APL by providing a specific interpreter, the semantics of which will prove to be equivalent to object-level 3APL.     

Event-based operational semantics and a consistency result for real-time concurrent processes with action refinement

In this paper an event-based operational interleaving semantics is proposed for real-time processes,for which action refinement and a denotational true concurrency semantics are developed and defined in terms of timed event structures. The authors characterize the timed event traces that are generated by the operational semantics in a denotational way, and show that this operational semantics is consistent with the denotational semantics in the sense that they generate the same set of timed event traces, thereby eliminating the gap between the true concurrency and interleaving semantics.     

Operational and goal-independent denotational semantics for Prolog with cut

In this paper we propose an operational and a denotational semantics for Prolog. We deal with the control rules of Prolog and the cut operator. Our denotational semantics provides a goal-independent semantics. This means that the behaviour of a goal in a program is defined as the evaluation of the goal in the denotation (semantics) of the program. We show how our denotational semantics can be specialised into a computed answer semantics and into a call pattern semantics. Our work provides a basis for a precise abstract interpretation of Prolog programs.