A unification-based approach for knowledge base verification

Abstract: Knowledge base verification, a part of the validation process in expert system development, includes checking the knowledge base for completeness and consistency to guard against a variety of errors that can arise during the process of transferring expertise from a human expert to a computer system. Regardless of how an expert system is developed, its developers can profit from a systematic check of the knowledge base without gathering extensive data for test runs, even before the full reasoning mechanism is functioning. Until recently knowledge base verification has been largely ignored, which has led to expert systems with knowledge base errors and no safety factors for correctness. We propose a unification-based approach for verification of a knowledge base represented in the form of production rules and facts. This approach can determine conflicting, redundant, subsumed and circular rules; redundant if-conditions in rules; dead-end rules; and cycles and contradiction in rules.     

基于Petri网的知识库维护方法的研究

Ｐｅｔｒｉ网作为建立系统模型，性能分析，模拟，系统调度，控制等方面的工具已在计算机各方面得到了很好的应用。本文主要探讨了Ｐｅｔｒｉ网在知识库维护方面的应用，包括知识库的正确性、一致性及完备性的检查。对大型知识库的建立及其维护具有重要意义。     

工艺设计知识库的建造与维护

文中根据工艺设计知识的特点,构造了层次化的知识表达、组织与知识库模型,分析了工艺知识库不一致的表现形式,并给出了相应的一致性验证算法,提出了基于广义决策表的知识库完备性检查方法。     

用于一致性检查的知识库Petri网模型

知识库是一致性是决定专家系统效率及求解正确性的关键因素。本文以Ｐｅｔｒｉ网为工具对知识库进行模拟分析，把知识库一致性的检查化简为线性代数问题，把这一方法应用于分布式知识库系统，首次得到了检查其一致性的形式方法。本文最后给出了一致性检查的充分必要条件，为建立（分布式）知识库的自动维护系统打下了基础。     

井下调度运输的自动调度策略研究

为了提高煤矿井下机车调度效率和实现井下调度系统自动化,基于Petri网理论知识结合实际井下矿场路况建立机车调度Petri网模型,然后对Petri网模型添加限制库所和变迁使其调度过程无死锁,并通过理论证明了该调度模型是无死锁和冲突的,可以指导机车井下运输调度.然后在机车调度规则下针对不同的井下机车调度相关参数,提出了3种...     

On Correctness of the Production Decision Model Based on the Decision Tables

Consideration was given to correctness (completeness and consistency) of the production decision model based on the decision tables and intended for the intelligent decision support systems used in the real-time control of complex plants and processes.     

无线传感器网络中一种能量高效的分布式分簇算法

提出了一种适用于无线传感器网络的能量高效的分布式分簇算法（ＥＥＤＣ）,该算法使具有较高剩余能量及距离基站较近的节点有更大的机会成为簇头．理论分析表明该算法通信开销较小,而且有效地均衡了节点的能量消耗．为了确保ＥＥＤＣ 的正确性、完整性和可靠性,利用形式化方法———着色网对其关键属性进行建模和分析．仿真结果表明,ＥＥＤＣ 有效地延长了网络生命周期,提高了网络的能耗效率．     

mwKAT: A meta-tool-generated knowledge acquisition tool for multimedia workstations development

mwKAT is an interactive knowledge acquisition tool for acquiring domain knowledge about multimedia components. It constructs knowledge bases for a consulting system that produces the design specification for a multimedia workstation according to the user requirements.mwKAT is generated from and executed inGAS, a primitives-based generic knowledge acquisition meta-tool. It contains three acquisition primitives, namely, parameter proposing, constraint proposing, and fix proposing to construct an intermediate knowledge base represented by a dependency model. These primitives identify necessary domain knowledge and guide users to propose significant components, constraints, and fix methods into the dependency model.mwKAT also invokes knowledge verification and validation primitives to verify the completeness, consistency, compilability, and correctness of the intermediate knowledge base.     

On generating FC3 fuzzy rule systems from data usingevolution strategies

Sophisticated fuzzy rule systems are supposed to be flexible, complete, consistent and compact (FC(3)). Flexibility, and consistency are essential for fuzzy systems to exhibit an excellent performance and to have a clear physical meaning, while compactness is crucial when the number of the input variables increases. However, the completeness and consistency conditions are often violated if a fuzzy system is generated from data collected from real world applications. A systematic design paradigm is proposed using evolution strategies. The structure of the fuzzy rules, which determines the compactness of the fuzzy systems, is evolved along with the parameters of the fuzzy systems. Special attention has been paid to the completeness and consistency of the rule base. The completeness is guaranteed by checking the completeness of the fuzzy partitioning of input variables and the completeness of the rule structure. An index of inconsistency is suggested with the help of a fuzzy similarity which can prevent the algorithm from generating rules that seriously contradict with each other or with the heuristic knowledge. In addition, soft T-norm and BADD defuzzification are introduced and optimized to increase the flexibility of the fuzzy system. The proposed approach is applied to the design of a distance controller for cars. It is verified that a FC(3) fuzzy system works very well both, for training and test driving situations, especially when the training data are insufficient.     

An algebraic approach to revising propositional rule-based knowledge bases

One of the important topics in knowledge base revision is to introduce an efficient implementation algorithm. Algebraic approaches have good characteristics and implementation method; they may be a choice to solve the problem. An algebraic approach is presented to revise propositional rule-based knowledge bases in this paper. A way is firstly introduced to transform a propositional rule-based knowledge base into a Petri net. A knowledge base is represented by a Petri net, and facts are represented by the initial marking. Thus, the consistency check of a knowledge base is equivalent to the reachability problem of Petri nets. The reachability of Petri nets can be decided by whether the state equation has a solution; hence the consistency check can also be implemented by algebraic approach. Furthermore, algorithms are introduced to revise a propositional rule-based knowledge base, as well as extended logic programming. Compared with related works, the algorithms presented in the paper are efficient, and the time complexities of these algorithms are polynomial.     

On correctness of information models

During the last decade a number of approaches to information modelling, or conceptual modelling, have been presented. In most approaches it is assumed that the correctness of an information model is decided from intuitive considerations, though formal methods may be applied.In this report we discuss three correctness criteria of information models, namely: consistency, satisfiability and completeness. The satisfiability of an information model in a universe of discourse can be formally checked by complementing the information model with a representation of concrete knowledge which is assumed to be complete. A formal basis for such correctness checking is presented. Further, the relationship between an information model and a conceptual schema is discussed, and an observed transformation problem is presented.     

自由选择工作流网的可靠完备化简规则集

流程化简技术是一种重要的商业流程模型分析方法.已有的非形式化化简方法因缺乏理论基础而无法保证完备性.基于Petri 网的化简方法应用范围不针对流程模型因而不能保证可靠性.提出了针对自由选择工作流网的一个可靠完备化简规则集,可靠性保证化简过程中这类模型的行为正确性被保持,完备性保证任意一个正确的此类工作流网最终都能被化简为最简形式.基于化简规则集给出可靠完备的合成规则集,用于流程模型的设计与精化.     

Learning transformation rules for semantic query optimization: adata-driven approach

An approach to learning query-transformation rules based on analyzing the existing data in the database is proposed. A framework and a closure algorithm for learning rules from a given data distribution are described. The correctness, completeness, and complexity of the proposed algorithm are characterized and a detailed example is provided to illustrate the framework     

新闻知识图谱中知识融合量化评估研究

现阶段检验知识图谱融合程度的方法大多是基于句法检查和实例检验的人工方法,或对知识库中的逻辑规则进行推理,以此判断图谱是否具有完备性和一致性,但缺少对知识融合量化评估的具体方法。提出了一种基于幂律定律的量化评估方法,并用融合后的长江大保护新闻知识图谱节点数进行验证,发现随着节点相似度的升高,当前图谱节点的融合度增加,融合后节点数急剧下降,幂律模型拟合优度良好,调整决定系数均大于0.98。这一检验方法可为新闻知识图谱的融合度检验提供新的标准。     

SEMANTICAL AND ONTOLOGICAL CONSIDERATIONS IN TELOS: A LANGUAGE FOR KNOWLEDGE REPRESENTATION DIMITRIS PLEXOUSAKIS

This paper focuses on the semantics of Telos, a language for representing knowledge about information systems. Telos is intended to support the development of information systems, especially in the requirements modeling phase. An object-oriented representational framework is supported by Telos. Its features include aggregation, generalization, and classification, the treatment of attributes as first-class objects and the explicit representation of time. Telos also provides an assertion sublanguage for expressing deductive rules and integrity constraints. A possible-worlds semantics is defined for Telos knowledge bases. This semantics is intended to capture the peculiarities involved in the interpretation of temporal expressions. The integration of time has also inspired the treatment of existence in Telos. An ontology of objects based on the property of existence is proposed. In the spirit of KRYPTON, Telos knowledge bases are specified functionally, in terms of the operations provided for querying and updating them. This knowledge-level analysis will allow us to specify exactly what a knowledge base can be ASK-ed or TELL-ed about the domain of discourse. Soundness, consistency, and completeness results have also been proven to complete the specification of Telos knowledge bases. This formal account of the language provides a logical framework that can be used to verify the correctness of any proposed implementation of the system.     

基于Petri网的服务组合故障诊断与处理

通过分析服务组合的故障需求,给出服务组合故障处理的框架.该框架采用Petri网来解决服务组合的错误发现及其处理问题.重点讨论了可用服务失败、组件失败及网络故障的情况,并相应地给出了服务组合故障模型.在此基础上对故障处理模型进行分析,给出服务组合故障处理正确性准则,并证明了其正确性.最后,采用CTL (computational tree logic)描述相关性质并提出验证服务组合故障分析的实施算法.仿真结果表明,该方法在处理服务组合故障时具有一定的优越性.     

A reasoning algorithm for high-level fuzzy Petri nets

We introduce an automated procedure for extracting information from knowledge bases that contain fuzzy production rules. The knowledge bases considered here are modeled using the high-level fuzzy Petri nets proposed by the authors in the past. Extensions to the high-level fuzzy Petri net model are given to include the representation of partial sources of information. The case of rules with more than one variable in the consequent is also discussed. A reasoning algorithm based on the high-level fuzzy Petri net model is presented. The algorithm consists of the extraction of a subnet and an evaluation process. In the evaluation process, several fuzzy inference methods can be applied. The proposed algorithm is similar to another procedure suggested by Yager (1983), with advantages concerning the knowledge-base searching when gathering the relevant information to answer a particular kind of query     

Calculating sharp adaptation rules

Adaptation rules adapt the pre-post specification of a procedure to contexts where it is called. Such rules are important for practical reasons and necessary for completeness for languages with recursive procedures. A sharp rule is one that gives the weakest precondition with respect to a given postcondition. A number of rules have been proposed, most unsound or incomplete or non-sharp. Using refinement algebra, we clarify and extend the applicability of previously proposed sharp rules for total correctness and show how further rules may be found.