共查询到19条相似文献,搜索用时 218 毫秒
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面向服务软件中服务间消息的变量值可能存在无穷域的情况,从而导致模型检测时产生状态空间爆炸问题。为了使终止性验证在实践上可行,需要约减模型状态空间的大小,使得计算时间和空间需求合理。为此,基于抽象解释的区间抽象理论扩展了经典区间抽象域方法,并在统一的区间抽象域方法上借助异常控制流图对变量进行区间分析,在此基础上逆向分析得到服务间消息的变量区间集。变量区间上任意值相对于终止性验证是等价性,因此从每一个变量区间集中选取一个代表值,可组成服务间消息变量的约减值,从而为异常处理的终止性验证提供了约减的初始配置,有效避免了状态空间爆炸。 相似文献
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通过对近年来软件模型检测领域流行的几种技术进行综述,提出了一种基于层次单元划分,使用引导式搜索方式的软件模型检测方案。本方案分为预处理、单元划分、状态空间搜索三个阶段,其中使用on-the-fly技术提高了搜索性能。实验证明,该方案在解决状态爆炸问题上有较好的效果。 相似文献
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隐蔽信息流分析是开发高等级可信计算机系统必须面对的问题.以Petri网作为开发安全系统的形式化建模工具,给出Petri网中隐蔽信息流存在的判定条件.提出该条件成立的两种网结构,进而可以在语法层次上预先判断隐蔽信息流的存在性,并使由此类结构引起的隐蔽信息流在系统的设计阶段得以避免.开发了一种基于Petri网可达图的隐蔽信息流存在性判定算法,算法遵循无干扰方法的思想,但是避免了无干扰方法中等价状态的区分和展开定理的使用.另外,算法采用深度优先搜索的策略,避免了Petri网全局可达图的构造.对复杂的安全系统,分析了子系统的各种组合运算对隐蔽信息流存在性的影响,降低了大规模系统分析的复杂度. 相似文献
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动态调整安全级是目前提高强制访问控制模型可用性的主要途径,它大致包括两类方法.其中,安全级范围方法对主体权限最小化的支持不够,而污点传播方法存在已知隐蔽通道.提出了保护操作系统保密性和完整性的广义污点传播模型(generalized taint propagation model,简称GTPM),它继承了污点传播在最小权限方面的特点,拓展了污点传播语义,以试图关闭已知隐蔽通道,引入了主体的降密和去污能力以应对污点积累;还利用通信顺序进程(CSP)语言描述了模型的规格,以明确基于GTPM的操作系统的信息流控制行为的形式化语义;基于CSP的进程等价验证模型定义了可降密无干扰,并借助FDR工具证明形式化构建的抽象GTPM系统具有可降密无干扰安全性质.最后,通过一个示例分析了模型的可用性提升. 相似文献
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抽象技术是解决模型检测状态空间爆炸的一种有效方法,但其中一个重大的障碍是对系统的抽象会引入原始系统中本来不存在的行为,即可能会引入虚假反例。因此,需要根据反例对抽象模型进行精化。如何判定一个反例是虚假反例还是真实反例,在抽象精化过程中相当重要。本文根据状态的前驱和后继定义失效状态,给出虚假反例的定义,并基于此提出检测虚假反例的并行算法。 相似文献
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分布式模型检测是一种缓解状态空间爆炸的有效途径,已有文献提出了定性的分布式模型验证算法,然而定量LTL验证算法并行化问题还未得到有效解决。对此,展开两个方面的工作:提出一种新的动态系统状态空间划分方法;在定性LTL分布式验证算法的基础上给出了定量模型检测并行化验证算法。首先,将系统模型转化为可能的Kripke结构并选取一个并发分量,依据状态之间的关系完成系统状态的分割,使得关系紧密的状态尽可能分布在同一个计算节点上;其次,调整划分结果以使得计算负载平衡;然后,将划分结果与其他并发分量的状态进行叉乘,以完成系统状态空间的划分;最后,将待检测性质用自动机表示,在两者的乘积上,利用扩展的基于嵌套DFS的分布式验证算法完成系统的定量验证。 相似文献
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The sh-verification tool comprises computing abstractions of finite-state behaviour representations as well as automata and
temporal logic based verification approaches. To be suitable for the verification of so called co-operating systems, a modified
type of satisfaction relation (approximate satisfaction) is considered. Regarding abstraction, alphabetic language homomorphisms
are used to compute abstract behaviours. To avoid loss of important information when moving to the abstract level, abstracting
homomorphisms have to satisfy a certain property called simplicity on the concrete (i.e. not abstracted) behaviour. The well
known state space explosion problem is tackled by a compositional method combined with a partial order method.
Received March 1997 / Accepted in revised form July 1998 相似文献
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Behaviour of systems is described by formal languages: the sets of all sequences of actions. Regarding abstraction, alphabetic language homomorphisms are used to compute abstract behaviours. To avoid loss of important information when moving to the abstract level, abstracting homomorphisms have to satisfy a certain property called simplicity on the concrete (i.e. not abstracted) behaviour. To be suitable for verification of so called co-operating systems, a modified type of satisfaction relation for system properties (approximate satisfaction) is considered. The well known state space explosion problem is tackled by a compositional method formalized by so called co-operation products of formal languages. 相似文献
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Data in business processes becomes more and more important. Current standard languages for process modeling like BPMN 2.0 which include the data flow reflect this. Ensuring the correctness of the data flow in processes is challenging. Model checking, i.e., verifying properties of process models, is a well-known technique to this end. An important part of model checking is the construction of the state space of the model. However, state-space explosion typically is in the way of an effective verification. We study how to overcome this problem in our context by means of reduction. More specifically, we propose a reduction on the level of the process model. To our knowledge, this is new for the data-flow analysis of processes. The core of our approach are so-called regions of the process model that are relevant for the verification of properties describing the data flow. Non-relevant regions are candidates for reduction of the process model, yielding a smaller state space. Our evaluation shows that our approach works well on industrial process models. 相似文献
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Verification of real-time systems is a complex problem, requiring construction of aregion automaton with a state space growing exponentially in the number of timing constraints and the sizes of constants in those constraints. However, some properties can be verified even when some quantitative timing information is abstracted. We propose a new verification procedure, where increasingly more complex abstractions of the region automaton are iteratively constructed. In many cases, the procedure can be stopped early, and thus can avoid the state space explosion problem. 相似文献
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Automated formal verification becomes a significant part of an industrial design process. Favourite formal verification method model checking is strongly limited by the size of the model of the verified system. It suffers from the so called state explosion problem. We propose to fight this problem by applying the idea of bounding the examined state space in explicit model checking. Moreover, we combine this approach with the distribution of the computation among the network of workstations. We consider several distributed bounded LTL model checking algorithms and carry out a series of experiments to evaluate them and to compare their behaviour. 相似文献
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Uppaal是一种对实时系统模型进行建模和验证的工具,PVS(Prototype Verification System)是开发和分析形式化规格说明的原型证明系统。介绍了Uppaal2PVS翻译器的设计与实现,给出了一种将用Uppaal生成的时间自动机规格说明翻译成PVS文件的方法,从而将模型检查问题转换成了定理证明问题,解决了潜在的状态空间爆炸问题。最后给出了一个实例。 相似文献