Datalog逻辑程序调用语义及其应用研究

提出Datalog逻辑程序调用语义和调用谓词,说明包含程序调用谓词的可更新U-Datalog程序的操作语义及其固定点语义。提出在有限分层调用情况下U-Datalog程序的通用评价(evaluation)算法。最后对Datalog程序调用语义在数字版权语言中的应用做了说明并给出示例。     

具有过去时态算子的计算树逻辑模型检测

在计算树逻辑(CTL)中引入过去时态算子,得到了表达力更强的属性规约语言CTLP,给出了CTLP 的模型检测算法及其固定点刻画.该算法的复杂性和CTL一样.固定点刻画使得CTLP的符号模型检测过程能够实现,从而有效克服了模型检测中的状态爆炸问题.     

具有过去时态算予的计算树逻辑模型检测

在计算树逻辑（CTL）中引入过去时态算子，得到了表达力更强的属性规约语言CTLP，给出了CTLP的模型检测算法及其固定点刻画。该算法的复杂性和CTL一样。固定点刻画使得CTLP的符号模型检测过程能够实现，从而有效克服了模型检测中的状态爆炸问题。     

一种面向DRM的责任授权模型及其实施框架

针对现有的DRM(digital rights management)机制缺乏真正的责任描述和实施能力问题,提出一种应用于DRM的责任授权模型及其实施框架.该模型基于分布式时态逻辑和Active-U-Datalog语法规则,具有表达事件驱动、时间驱动和责任补偿等各类责任授权的语义能力,并具有良好的可实施性.对该模型的语法语义进行了分析和说明,描述了责任实施机制,并对该模型的实现、应用和表达力进行了说明和示例.该模型提高了DRM系统对数据使用控制的灵活性和能力.     

程序推理

前文“结构式时态语义”中定义了程序语言的一种时态语义,这种语义是语法引导的(Syntax Directed),保持语言的结构。本文中讨论在这种语义基础上的程序推理问题。因为这是时态语义,故在程序描述中可使用时态逻辑的丰富的表达力;又因为它是结构式的,故关于各种语句已有的推理方法,都可以翻译为时态逻辑中的定理,随意应用。     

DTL-Real-Time Object-Z形式化规格说明语言及其责任授权模型描述

Object-Z语言缺乏完整的时态描述能力,如无法表达操作在特定时间之后执行或按某种周期执行等,也不具有操作补偿等概念。针对这些问题,在Object-Z中集成实时概念和分布式时态逻辑,提出DTL-Real-Time Object-Z规格语言,该语言能有效地描述操作的时态驱动、事件驱动、操作补偿等因素,分析和说明了该语言的语法和语义,最后通过对责任授权模型的形式化描述说明了该语言的表达能力和应用。     

语义Web规则标记语言OWLRule+的设计与实现

语义Web是对未来Web体系结构的一个伟大设想，其研究分层次进行．目前足够成熟的最高层是以OWL语言为代表的ontology．但它的语义仅限于描述逻辑，该逻辑主要表示对象和类的层次结构，而规则的表达能力弱，因此在其之上需要一种表达力更丰富的逻辑语言．设计了一种新的语义Web规则标记语言OWLRule ：其语法扩展了OWL；语义基于CARIN，一种结合描述逻辑和Horn规则的表示语言；实现基于Jess规则推理机．实例学习展示了它对目前的Web ontology语言在规则表示和推理能力上的扩展．     

一种基于逻辑框架的数字版权管理机制和实现

权利描述语言用来构造许可证,描述数字内容的使用权利.鉴于现存的权利描述语言存在表达力不足、缺乏正式语义等问题,提出一种基于逻辑框架的数字版权管理语言LucScript.对该语言框架的逻辑语义、语法和触发运行机制进行了分析和说明,描述了该语言的实现方法,并对该语言的应用和使用控制过程进行了示例.该语言基于统一的具有单一稳态结构的Active-U-Datalog语义,具有比现存权限描述语言更强的表达力和灵活性.LucScript语言可有效地提高DRM系统对数据内容使用的灵活性和实时控制能力.     

时态RDF扩展及其SPARQL查询语言

随着语义网的快速发展以及RDF框架（资源描述框架）的普遍应用,对含有时间信息的数据处理的需求越来越多,经典RDF模型由其本身结构特点缺乏表示和处理时间信息的能力,而且针对时态RDF的研究罕有得见。通过对经典RDF模型添加时间戳表示其时间维度,并对时态RDF图中的蕴含问题进行了讨论,根据SPARQL查询语言提出了完备的时态RDF查询语言Tsparql,并对提出的查询语言进行可行性以及性能进行了实验仿真。利用该时态RDF模型表示如股票、天气、新闻等具有时态特性的资源有优势,Tsparql对时态RDF进行查询具有良好的表达力和兼容性。     

带权重谓词的可选事务逻辑及其访问控制应用

逻辑语言由于其表达力和灵活性,是访问控制中授权语言的基础之一。针对Datalog语言缺乏表达事务和多方决策模型的能力,对Datalog进行了扩展,提出了一种带权重谓词的可选事务逻辑WT-Logic。首先对WT-Logic的语法、语义进行了说明;然后解释了其评价方法;最后对WT-Logic语言在工作流授权和多方投票机制中的应用进行了描述和示例,说明了WT-Logic的表达力和可应用性。     

Contributions to the semantics of logic perpetual processes

Summary Logic perpetual processes (logic programs with infinite data structures) have been given several formal (operational and fixpoint) semantics. In this paper, we compare the various semantics and define a formal characterization of a least fixpoint semantics, which is based on a modified version of the logic programs and which is satisfactory for a large class of logical perpetual processes. Our results show that all the proposed fixpoint semantics are not equivalent to the operational semantics and suggest an improvement of the least fixpoint approach.     

Static analysis of logical languages with deferred update semantics

Static analysis of declarative languages deals with the detection, at compile time, of program properties that can be used to better understand the program semantics and to improve the efficiency of program evaluation. In logical update languages, an interesting problem is the detection of conflicting updates, inserting and deleting the same fact, for transactions based on set-oriented updates and active rules. In this paper, we investigate this topic in the context of the U-Datalog language, a set-oriented update language for deductive databases, based on a deferred semantics. We first formally define relevant properties of U-Datalog programs, mainly related to update conflicts. Then, we prove that the defined properties are decidable and we propose an algorithm to detect such conditions. Finally, we show how the proposed techniques can be applied to other logical update languages. Our results are based on the concept of labeling and query-tree.     

Formal timing analysis of distributed systems

Although a large number of formal methods have been reported in the literature, most of them are applicable only at the initial stages of software development. A major reason for this situation is that those formalisms lack expressiveness to describe the behavior of systems with respect to their underlying configurations. On the other hand, recent experience has shown that the complex nature of distributed systems is conveniently described, constructed and managed in terms of their configuration. In this context, with the twin objectives of accurately modelling the real-timed behavior of distributed systems and supporting the analysis of timing behavior with respect to their underlying configurations, we formulate a logic language called distributed logic (DL). DL is a first-order logic augmented with temporal and spatial modalities. The semantics of DL are based on ideas drawn from both the interleaving and partial order models. In addition to the syntax and semantics of the logic, a formal proof scheme for a distributed programming model is also presented. Finally, use of the proof method is illustrated through the analysis of the real-time properties of a sample problem.     

Operational semantics of Framed Tempura

This paper investigates the operational semantics of temporal logic programs. To this end, a temporal logic programming language called Framed Tempura is employed. The evaluation rules for both the arithmetic and boolean expressions are defined. The semantic equivalence rules for the reduction of a program within a state is formalized. Furthermore, the transition rules within a state and transition rules over an interval between configurations are also specified. Moreover, some examples are given to illustrate how these rules work. Thus, the executable behavior of framed programs can be captured in an operational way. In addition, the consistency between the operational semantics and the minimal model semantics based on model theory is proved in detail.     

Bottom-up Evaluation of Datalog with Negation

Declarative semantics gives the meaning of a logic program in terms of properties,while the procedural semantics gives the meaning in terms of the execution or evaluation of the program.From the database point of view,the procedural semantics of the program is equally important.This paper focuses on the study of the bottom-up evaluation of the WFM semantics of datalog‘ programs.To compute the WFM,first,the stability transformation is revisited,and a new operator Op and its fixpoint are defined. Based on this,a fixpoint semantics,called oscillating fixpoint model semantics,is defined.Then,it is shown that for any datalog‘ program the oscillating fixpoint model is identical to its WFM.So,the oscillating fixpoint model can be viewed as an alternative (constructive) definition of WFM.The underlying operation (or transformation) for reaching the oscillating fixpoint provides a potential of bottom-up evaluation.For the sake of computational feasibility,the strongly range-restricted program is considered,and an algorithm used to compute the oscillating fixpoint is described.     

容错的网络声明式程序

介绍了基于递归规则的网络声明式语言Netlog的语法和分布式不动点语义,定义了强良好的程序,并证明了强良好的程序的计算结果对有限的消息丢失不敏感.