一个命题投影时序逻辑符号模型检测器

现有模型检测工具的形式化规范语言,如计算树逻辑(computation tree logic,简称CTL)和线性时序逻辑(linear temporal logic,简称LTL)等的描述能力不足,无法验证ω正则性质.提出了一个命题投影时序逻辑(propositional projection temporal logic,简称PPTL)符号模型检测工具——PLSMC(PPTL symbolic model checker)的设计与实现过程.该工具基于著名的符号模型检测系统NuSMV,实现了PPTL的符号模型检测算法.PLSMC的规范语言PPTL具有完全正则表达能力,这使得定性性质和定量性质均可被验证.此外,PLSMC可以有效地缓解模型检测工具中容易发生的状态空间爆炸问题.最后,利用PLSMC对铁路公路交叉道口护栏控制系统的安全性质和周期性性质进行验证.实验结果表明,PPTL符号模型检测工具扩充了NuSMV系统的验证能力,使得时间敏感、并发性和周期性等实时性质可以被描述和验证.     

支持索引式的PPTL定理证明器的实现

定理证明是目前主流的形式化验证方法,拥有强大的抽象和逻辑表达能力,且不存在状态空间爆炸问题,可用于有穷和无穷状态系统,但其不能完全自动化,并且要求用户掌握较强的数学知识.含索引式的命题投影时序逻辑(PPTL)是一种具有完全正则表达能力,并且包含LTL的时序逻辑,具有较强的建模和性质描述能力.目前,一个可靠完备的含索引式的PPTL公理系统已被构建,然而基于该公理系统的定理证明尚未得到良好工具的支持,存在证明自动化程度较低以及证明冗长易错的问题.鉴于此,首先设计了支持索引式的PPTL定理证明器的实现框架,包括公理系统的形式化与交互式定理证明;然后,在Coq中形式化定义了含索引式的PPTL公式、公理与推理规则,完成了框架中公理系统的实现;最后,通过两个实例的交互式证明验证了该定理证明器的可用性.     

时序逻辑语言XYZ/E中指针的形式化表示与验证

指针是一种重要的数据类型,使用指针能使程序更加有效和优美.可是指针却以不易驾御而闻名,至今在时序逻辑语言中未见到对它的形式化工作.XYZ/E既是一个时序逻辑系统也是一个程序设计语言,它能表示普通高级语言中几乎所有的重要机制.本文主要讨论在时序逻辑语言XYZ/E中指针的形式化表示问题以及在结构化XYZ/SE程序中指针的验证问题.     

基于事件确定有限自动机的UML2.0 序列图描述与验证

为了确保软件分析与设计阶段UML2.0序列图模型的可靠性,采用命题投影时序逻辑(propositional projection temporal logic,简称PPTL)模型检测方法对该模型进行分析和验证.提出了事件确定有限自动机(event deterministic finite automata,简称ETDFA),并使用该自动机为序列图建立形式化模型,通过给出的基于ETDFA的PPTL模型检测算法得到验证结果.该方法可以在基于Spin的PPTL模型检测器的支持下实现.实例结果表明,该方法可以验证序列图的性质并保证其可靠性.     

基于命题投影时序逻辑的单调速率调度算法模型检测

提出了基于命题投影时序逻辑(propositional projection temporal logic,简称PPTL)的单调速率调度(rate monotonic scheduling,简称RMS)模型检测方法.该方法使用SPIN模型检测器的系统建模语言PROMELA为任务调度系统建模,使用PPTL描述系统期望的性质,通过SPIN验证系统模型是否满足性质,从而得知一个任务组在RMS下是否可调度.同时,RMS算法控制下的任务调度系统的其他性质也可以得到验证.     

一种汇编语言指针逻辑的设计与实现

软件的安全性日益重要,软件满足安全策略的证明方法成为一个研究热点.而指针程序的安全性质证明是难点之一.根据已经提出的安全程序设计与证明的框架以及PointerC指针逻辑,提出一种汇编语言指针逻辑.该逻辑解决了Hoare逻辑处理别名问题面临的困难,保证通过验证的汇编指针程序不存在空指针引用和内存泄露等安全问题.此逻辑的可靠性证明已在证明辅助工具Coq中完成.此外,本文还实现一个原型系统,并使用该系统对链表、二叉树等非平凡的指针程序的进行了自动的安全验证.     

程序性质的描述与证明

XYZ/E是一种基于Manna-Pnueli线性时序逻辑的线性时序逻辑语青(LTLL),其主要特征为它在统一的时序逻辑框架下既能表示程序的静态规范(XYZ/AE)也能表示可执行代码(XYZ/EE),因此程序规范和程序可执行代码的语义一致性也就得以在时序逻辑框架下验证。对于顺序程序,XYZ系统提供了一套基于Hoare逻辑规则的验证工具XYZ/VERI。此工具通过读取程序及其前后断     

编译执行在可编程逻辑控制器上的实现

传统的可编程逻辑控制器(PLC)采用解释执行方式执行梯形图,执行效率低下.对此该文提出以编译执行方式代替解释执行方式来提高执行效率.但通常的编译执行方式实现难度巨大,因此本文提出利用GNU编译器集(GCC)实现编译执行的解决方法.即先将梯形图转换为C语言程序,然后通过GCC的开放平台得到编译执行所需的各工具,并运用这些工具编译C语言程序从而实现PLC的编译执行方式.测试表明编译执行的PLC执行效率大幅提升.     

安全语言PointerC的设计及形式证明

程序设计语言本身的安全性在高安全需求软件的设计和实现中起着基础作用.该文在用于系统级编程的安全语言的设计和性质证明方面,做了有益的尝试.作者设计了一个类C的命令式语言PointerC,其主要特点在于其类型系统中包含显式的副条件(side conditions),这些副条件本质上是约束程序语法表达式值的逻辑公式.该文证明了PointerC语言的安全性定理,即满足这些副条件的程序,在执行时不会违反语言的安全策略.为静态推理副条件中涉及指针的命题,作者已经提出了一种指针逻辑(pointer logic),文中证明了指针逻辑对操作语义是可靠的.     

基于CCS执行模型的逻辑式语言POLYLOG的设计与实现

本文解决了逻辑式程序设计语言中的二个问题:并行执行模型的选择、语言的执行功效与其使用方便灵活之间的权衡,我们提出了对Algorithm=Logic+Control的新理解, 设计并实现了新型逻辑式语言POLYLOG,在POLYLOG中,我们引进了元级控制的概念,CCS执行模型作为内部隐含的元级控制机制,关系类型作为外部显式的元级控制设施,程序的并行性分析在编译阶段完成。     

Closure via functional dependence simplification

In this paper, a method for computing the closure of a set of attributes according to a specification of functional dependencies of the relational model is described. The main feature of this method is that it computes the closure using solely the inference system of the SL _FD logic. For the first time, logic is used in the design of automated deduction methods to solve the closure problem. The strong link between the SL _FD logic and the closure algorithm is presented and an SL _FD simplification paradigm emerges as the key element of our method. In addition, the soundness and completeness of the closure algorithm are shown. Our method has linear complexity, as the classical closure algorithms, and it has all the advantages provided by the use of logic. We have empirically compared our algorithm with the Diederich and Milton classical algorithm. This experiment reveals the best behaviour of our method which shows a significant improvement in the average speed.     

Expressiveness of propositional projection temporal logic with star

This paper investigates the expressiveness of Propositional Projection Temporal Logic with Star (PPTL*). To this end, Büchi automata and ω-regular expressions are first extended as Stutter Büchi Automata (SBA) and Extended Regular Expressions (ERE) to include both finite and infinite strings. Further, by equivalent transformations among PPTL* formulas, SBAs and EREs, PPTL* is proved to represent exactly the full regular language. Moreover, some fragments of PPTL* are characterized, and finally, PPTL* and its fragments are classified into five different language classes.     

Adding a temporal dimension to a logic system

We introduce a methodology whereby an arbitrary logic system L can be enriched with temporal features to create a new system T(L). The new system is constructed by combining L with a pure propositional temporal logic T (such as linear temporal logic with Since and Until) in a special way. We refer to this method as adding a temporal dimension to L or just temporalising L. We show that the logic system T(L) preserves several properties of the original temporal logic like soundness, completeness, decidability, conservativeness and separation over linear flows of time. We then focus on the temporalisation of first-order logic, and a comparison is make with other first-order approaches to the handling of time.     

Completeness of a combination of neighbourhood logic and temporal logic

This paper presents a completeness result, with respect to a possible world semantics, for a combination of a first-order temporal logic and neighbourhood logic. This logic was considered by Qiu and Zhou (1998, Proceedings of the PROCOMET 98, pp 444–461) to define semantics of a real-time OCCAM-like programming language.Received June 1999Accepted in revised form September 2003 by M. R. Hansen and C. B. Jones     

Programming in temporal-nonmonotonic reasoning

Nonmonotonic reasoning has been proposed as an extension to classical first-order logic. Now people are interested in temporal reasoning with nonmonotonic logic [6]. We combine the monotonic logic [7] with a temporal logic to get a more general reasoning language. We discuss a monotonic logic TML which has predicate formulas, temporal formulas and a special modal formula, and give a completeness theorem of it. We use TH() to designate the set of theorems of a temporal-nonmonotonic theory which has the same language with TML. The completeness theorem of the temporal-nonmonotonic logic naturally arises. Like the relationship between predicate logic with a practical logic programming language PROLOG, we propose a useful temporal-nonmonotonic reasoning language TN for the temporal-nonmonotonic logic. As an appendix we supply an algorithm for the programming language TN.     

面向MSVL的智能合约形式化验证

智能合约是运行在区块链上的计算机协议,被广泛应用在各个领域中,但是其安全问题层出不穷,因此在智能合约部署到区块链上之前需要对其进行安全审计,然而,传统的测试方法无法保证智能合约所需的高可靠性和正确性.说明了如何使用建模、仿真与验证语言（MSVL）和命题投影时序逻辑（PPTL）对智能合约进行建模和验证,首先介绍了MSVL与PPTL的理论基础;之后通过分析和对比了Solidity与MSVL语言的特性,开发了能够将Solidity程序转换为MSVL程序的SOL2M转换器,并详细介绍了SOL2M转换器的设计思路;最终通过投票智能合约和银行转账智能合约两个实例,给出了SOL2M转换器的执行结果,使用PPTL从功能一致性、逻辑正确性以及合约完备性三个方面描述了合约的性质,给出了使用统一模型检测器（UMC4M）对合约进行验证的过程.     

Weak Updates and Separation Logic

Separation logic provides a simple but powerful technique for reasoning about low-level imperative programs that use shared data structures. Unfortunately, separation logic supports only “strong updates,” in which mutation to a heap location is safe only if a unique reference is owned. This limits the applicability of separation logic when reasoning about the interaction between many high-level languages (e.g., ML, Java, C#) and low-level ones since the high-level languages do not support strong updates. Instead, they adopt the discipline of “weak updates,” in which there is a global “heap type” to enforce the invariant of type-preserving heap updates. We present SL ^w , a logic that extends separation logic with reference types and elegantly reasons about the interaction between strong and weak updates. We describe a semantic framework for reference types, which is used to prove the soundness of SL ^w . Finally, we show how to extend SL ^w with concurrency.