Syntax and semantics of the compositional interchange format for hybrid systems

Different modeling formalisms for timed and hybrid systems exist, each of which addresses a specific set of problems, and has its own set of features. These formalisms and tools can be used in each stage of the embedded systems development, to verify and validate various requirements.The Compositional Interchange Format (CIF), is a formalism based on hybrid automata, which are composed using process algebraic operators. CIF aims to establish interoperability among a wide range of formalisms and tools by means of model transformations and co-simulation, which avoids the need for implementing many bilateral translators.This work presents the syntax and formal semantics of CIF. The semantics is shown to be compositional, and proven to preserve certain algebraic properties, which express our intuition about the behavior of the language operators. In addition we show how CIF operators can be combined to implement widely used constructs present in other timed and hybrid formalisms, and we illustrate the applicability of the formalism by developing several examples.Based on the formal specification of CIF, an Eclipse based simulation environment has been developed. We expect this work to serve as the basis for the formal definition of semantic preserving transformations between various languages for the specification of timed and hybrid systems.     

A layered semantics for a parallel object-oriented language

We develop a denotational semantics for POOL, a parallel object-oriented programming language. The main contribution of this semantics is an accurate mathematical model of the most important concept in object-oriented programming: the object. This is achieved by structuring the semantics in layers working at three different levels: for statements, objects and programs. For each of these levels we define a specialized mathematical domain of processes, which we use to assign a meaning to each language construct. This is done in the mathematical framework of complete metric spaces. We also define operators that translate between these domains. At the program level we give a precise definition of the observable input/output behaviour of a particular program, which could be used at a later stage to decide the issue of full abstractness. We illustrate our semantic techniques by first applying them to a toy language similar to CSP.This paper describes work done in ESPRIT Basic Research Action 3020,Integration.     

The formal definition of a real-time language

Summary This paper presents the formal definition of TOMAL (Task-Oriented Microprocessor Applications Language), a programming language intended for real-time systems running on small processors. The formal definition addresses all aspects of the language. Because some modes of semantic definition seem particularly well-suited to certain aspects of a language, and not as suitable for others, the formal definition employs several complementary modes of definition.The primary definition is axiomatic and is employed to define most statements of the language. Simple, denotational (but not lattice-theoretic) semantics complement the axiomatic semantics to define type-related features, such as binding of names to types, data type coercions, and evaluation of expressions. Together, the axiomatic and denotational semantics define all features of the sequential language. An operational definition is used to define real-time execution, and to extend the axiomatic definition to account for all aspects of concurrent execution. Semantic constraints, sufficient to guarantee conformity of a program with the axiomatic definition, can be checked by analysis of a TOMAL program at compilation.     

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。     

Equivalence of formal semantics definition methods

There are numerous methods of formally defining the semantics of computer languages. Each method has been designed to fulfil a different purpose. For example, some have been designed to make reasoning about languages as easy as possible; others have been designed to be accessible to a large audience and some have been designed to ease implementation of languages. Given two semantics definitions of a language written using two separate semantics definition methods, we must be able to show that the two are in fact equivalent. If we cannot do this then we either have an error in one of the semantics definitions, or more seriously we have a problem with the semantics definition methods themselves.Three methods of defining the semantics of computer languages have been considered, i.e. Denotational Semantics, Structural Operational Semantics and Action Semantics. An equivalence between these three is shown for a specific example language by first defining its semantics using each of the three definition methods. The proof of the equivalence is then constructed by selecting pairs of the semantics definitions and showing that they define the same language.A full version of this paper can be accessed via our web page http://www.cs.man.ac.uk/fmethods/ facj.html     

Extending the ODMG object model with triggers

We extend the standard for object-oriented databases, ODMG, with reactive features, by proposing a language for specifying triggers and defining its semantics. This extension has several implications, thus we make three different specific contributions. First, the definition of a declarative data manipulation language for ODMG, which is missing in the current version of the standard; such a definition requires revisiting data manipulation in ODMG and also addressing issues related to set-oriented versus instance-oriented computation. Then, the definition of a trigger language for ODMG, unifying also the SQL:1999 proposal and providing support for trigger inheritance and overriding. Finally, the development of a formal semantics for the proposed data manipulation and trigger languages.     

Reduction Semantics and Formal Analysis of Orc Programs

Orc is a language for orchestration of web services developed by J. Misra that offers simple, yet powerful and elegant, constructs to program sophisticated web orchestration applications. The formal semantics of Orc poses interesting challenges, because of its real-time nature and the different priorities of external and internal actions. In this paper, building upon our previous SOS semantics of Orc in rewriting logic, we present a much more efficient reduction semantics of Orc, which is provably equivalent to the SOS semantics thanks to a strong bisimulation. We view this reduction semantics as a key intermediate stage towards a future, provably correct distributed implementation of Orc, and show how it can naturally be extended to a distributed actor-like semantics. We show experiments demonstrating the much better performance of the reduction semantics when compared to the SOS semantics. Using the Maude rewriting logic language, we also illustrate how the reduction semantics can be used to endow Orc with useful formal analysis capabilities, including an LTL model checker. We illustrate these formal analysis features by means of an online auction system, which is modeled as a distributed system of actors that perform Orc computations.     

SEMANOL (73) a metalanguage for programming the semantics of programming languages

Summary SEMANOL is a practical programming system for writing readable formal specifications of the syntax and semantics of programming languages. SEMANOL is based on a theory of semantics which embraces algorithmic (operational) and extensional (input/output) semantics. Specifications for large contemporary languages have been constructed in the formal language, SEMANOL (73), which is a readable high-level notation. A SEMANOL (73) specification can be executed (by an existing interpreter program); when given a program from the specified language, and its input, the execution of the SEMANOL (73) specification produces the program's output. The demonstrated executability of SEMANOL (73) provides important practical advantages. This paper includes discussions of the theory of semantics underlying SEMANOL, the syntax and semantics of the SEMANOL (73) language, the use of the SEMANOL (73) language in the SEMANOL method for describing programming languages, and the contrast between the Vienna definition method (VDL) and SEMANOL.     

ICSL:一种用于仿真实体智能化控制的脚本语言

研究一种用于仿真实体智能化控制的脚本语言ICSL(Intelligent Control Scripting Language)．分析领域特征,将语言的语义划分为领域相关语义和领域无关语义;对领域相关语义进行编码,结合形式化描述方法和构造工具,定义ICSL并实现其解释器;通过解释器将ICSL,语言描述的智能化控制策略翻译为仿真系统中实体的行为序列,为用户提供了一种灵活表达控制策略的手段．此外,ICSL还采用元数据控制策略实现了多个侧面的扩充机制,从而解决了语言系统难以定制和演化的问题．     

An executable object-oriented semantics and its application to firewall verification

This paper presents a formal executable semantics of object-oriented models. We made it possible to conduct both simulation and theorem proving on the semantics by implementing it within the expressive intersection of the functional programming language ML and the theorem prover HOL. In this paper, we present the definition and implementation of the semantics. We also present a prototype verification tool ObjectLogic which supports simulation and theorem proving on the semantics. As a case study, we show the verification of a practical firewall system.     

Web服务编排描述语言WS—CDL的形式化模型框架

Web服务编排描述语言WS-CDL从全局的角度定义了一组Web服务之间的协作和交互必须遵守的规则。作为一个基于XML的描述性规范语言，WS-CDL缺乏形式化的模型和验证机制，难以保证协作和交互的正确性。本文针对WS-CDL规范提出了一个基于全局的形式化模型框架Abstract WS-CDL，包括语法、同构关系和操作语义，同时定义了一套从该模型框架到基于Pi-演算描述的局部模型的映射规则，最后通过案例分析给出了全局和局部2个层次的模型验证方法。     

基于参照的对词结构操作语义的归纳学习

心理语言学的研究和认知发展过程证明在语言获得的早期经历了一个自主的归纳学习过程,本文的出发点是语言发展的规律,并将词结构形式语义的获得过程和表示基础放在一个具有统一的语言理解和语言产生机制的语言信息加工模型中来考虑。本文讨论了一个基于实例的机器学习系统,为了获得词结构的形式语义,采用了操作语义的定义,并设计了一个基于参照的发现学习算法,其目的是使语义能伴随例句样本的丰富而精密化。     

Failure-based equivalence of constraint automata

Constraint automata are the first-proposed operational semantics of Reo coordination language. They can be composed not only by all well-defined composition operators of labeled transition systems but also by two new operators. The new operators are joining of constraint automata with respect to their common port names and hiding a port name in all transition labels. The operations of these two extra operators depend on the internal structures of the transition labels, while in the others each transition label is considered as a simple entity. An equivalence relation between transition systems is a congruence relation if the replacement of the components of a model by the equivalent ones always yields a model that is equivalent with the original one. Obviously, this definition of the congruency depends on the operators which are used to compose the components of models. This paper introduces four congruency results: we prove that failure-based equivalence relation CFFD (chaos-free failures divergences relation) is a congruence relation with respect to joining of constraint automata and also with respect to hiding port names in a constraint automaton. We also show that these are cases for equivalence relation NDFD (non-divergent failures divergences).     

A semantics for Behavior Trees using CSP with specification commands

In this paper we give a formal definition of the requirements translation language Behavior Trees. This language has been used with success in industry to systematically translate large, complex, and often erroneous requirements documents into a structured model of the system. It contains a mixture of state-based manipulations, synchronisation, message passing, and parallel, conditional, and iterative control structures. The formal semantics of a Behavior Tree is given via a translation to a version of Hoare’s process algebra CSP, extended with state-based constructs such as guards and updates, and a message passing facility similar to that used in publish/subscribe protocols. We first provide the extension of CSP and its operational semantics, which preserves the meaning of the original CSP operators, and then the Behavior Tree notation and its translation into the extended version of CSP.     

An institution theory of formal meta-modelling in graphically extended BNF

Meta-modelling plays an important role in model driven software development.In this paper,a graphic extension of BNF (GEBNF) is proposed to define the abstract syntax of graphic modelling languages.Fro...     

短语结构制导的范畴表达式演算

对于语言表达式的组成成分及它们间的关系的刻画,目前大多数语法研究都着重在句法层面,而本文的范畴表达式演算理论则着重在语义层面。我们首先考察了完全表达式与不完全表达式、句法类型与语义类型、继承、顺序、提取、并列等若干重要的语言现象以及各种语法理论对这些现象的解释,然后提出范畴表达式的形式化定义,分析了句法层面的形式约束对语义层面的内容组织的制导作用,并且用典型的语言例子直观的说明了如何利用短语结构制导,进行范畴表达式的演算。这种机制可形式化、可验证,能很好的捕捉语言的组成成分及它们间的相互关系,揭示一个句子所说的内容。