A Goal-Type Driven Method of Solving Horn Logic with Equality

A new method of solving Horn logic with equality,the goal-type driven method,is presented,which considers explicitly the unification operator as a gloal and merged it into the resolution process,The metho has the following advantages.The resolution and the unification have been integrated in a uniform way.The architectures of the inference engines based on Horn logic with equality are simplified,Any techniques of exploiting AND/OR parallelism to solve goals can also be applied to unification at the same time.The method can be used to integrate the styles of functional language and logic language by a uniform framework.It can also deal with infinite data structures.     

Program Constructionby Verifying Specification

A program construction method based on Gamma language is proposed.The problem to be solved is specified by first-order predicate logic and a semantic verification program is constructed directly from the specification.Ways for improving efficiency of the program are also studied.The method differs from the one proposed by Manna and Waldinger,where a program is extracted from the proof of the existence of an object meeting the given specification.On the other hand,it also differs from the classical one used for deriving Gamma programs of Banatre and Le metayes,which consists in decomposing the specification into an invariant and a termination conditon.     

A Fixpoint Semantics for Stratified Databases

Przmusinski extended the notion of stratified logic programs,developed by Apt,Blair and Walker,and by van Gelder,to stratified databases that allow both negative premises and disjunctive consequents.However,he did not provide a fixpoint theory for such class of databases.On the other hand,although a fixpoint semantics has been developed by Minker and Rajasekar for non-Horn logic programs,it is tantamount to traditional minimal model semantics which is not sufficient to capture the intended meaning of negation in the premises of clauses in stratified databases.In this paper,a fixpoint approach to stratified databases is developed,which corresponds with the perfect model semantics.Moreover,algorithms are proposed for computing the set of perfect models of a stratified database.     

Abstract Implementation of Algebraic Specifications in a Temporal Logic Language

A formal technique for incorporating two specification paradigms is presented,in which an algebraic specification is implemented by a set of abstract procedures specified in pre and post-condition style.The link between the two level specifications is provided via a translation from terms of algebraic specifications into temporal logic formulae representing abstract programs.In terms of translation,a criterion for an abstract implementation satisfying its specification is given,which allows one to check the consistency between the two levels of specifications.The abstract implementations can be refined into executable code by refining each abstract procedure in it.It is proved that the satisfication relation between a specification and its implementations is preserved by such refinement steps.     

Type-2 fuzzy control for a flexible-joint robot using voltage control strategy

Type-1 fuzzy sets cannot fully handle the uncertainties. To overcome the problem, type-2 fuzzy sets have been proposed. The novelty of this paper is using interval type-2 fuzzy logic controller (IT2FLC) to control a flexible-joint robot with voltage control strategy. In order to take into account the whole robotic system including the dynamics of actuators and the robot manipulator, the voltages of motors are used as inputs of the system. To highlight the capabilities of the control system, a flexible joint robot which is highly nonlinear, heavily coupled and uncertain is used. In addition, to improve the control performance, the parameters of the primary membership functions of IT2FLC are optimized using particle swarm optimization (PSO). A comparative study between the proposed IT2FLC and type-1 fuzzy logic controller (T1FLC) is presented to better assess their respective performance in presence of external disturbance and unmodelled dynamics. Stability analysis is presented and the effectiveness of the proposed control approach is demonstrated by simulations using a two-link flexible-joint robot driven by permanent magnet direct current motors. Simulation results show the superiority of the IT2FLC over the T1FLC in terms of accuracy, robustness and interpretability.     

Improved method to generate path-wise test data

Gupta et al.,propsed a method ,which is referred to as the Iterative Relaxation Method ,to generate test data for a given path in a program by linearizing the predicate functions.In this paper,a model language is presented and the properties of static and dynamic data depen-dencies are investigated ,The notions in the Interative Relaxation Method are defined formally.The predicate slice proposed by Gupta et al.is extended to path-wise static slice.The correctness of the constructional algorithm is proved afterward The improvement shows that the constructions of predicate slice and input dependency set can be omitted .The equivalence of systems of constraints generated by both methods is proved ,The prototype of path-wise test data generator is presented in this paper,The experiments show shat our method is practical ,and fits the path-wise automatic generation of test data for both whicte -bos testing and black-blx testing.     

2-D EAG Method for the Recognition of Hand-Printed Chinese Characters

A method, called Two-Dimensional Extended Attribute Grammars (2-DEAGs). for the recognition ofhand-printed Chinese characters is presented. This method uses directly two dimensional information, and pro-vides a scheme for dealing with various kinds of specific cases in a uniform way. In this method, componentsare drawn in guided and redundant way and reductions are made level by level just in accordance with the com-ponent combination relations of Chinese characters. The method provides also polysemous grammars,coexisting grammars and structure inferrings which constrain redundant recognition by comparison among similarcharacters or components and greatly increase the tolerance ability to distortion.     

2-D EAG Method for the Recognition of Hand-Printed Chinese Characters

A method,called Two-Dimensional Extended Attribute Grammars(2-D EAGs) for the recognition of hand-printed Chinese characters is presented.This method uses directly two dimensional information,and provides a scheme for dealing with various kinds of specific cases in a uniform way.In this method,components are drawn in guided and redundant way and reductions are made level by leve just in accordance with the component combination relations of Chinese characters.The method provids also polysemous grammars,coexisting grammars and structure inferrings whih constrain redundant recognition by comparison among similar characters of components and greatly increase the tolerance ability to distortion.     

Low-power design and application based on CSD optimization for a fixed coefficient multiplier

This paper presents a low-power design for a fixed coefficient multiplier,based on the canonic signed digit (CSD) method.The proposed technology overcomes the defects of the general CSD method by reducing system power and area substantially without additional logic.The theoretical basis and a design method are explained in detail in this paper.Our design technology was used to optimize a radio-frequency module.FPGA test results show that logic utilization is reduced by 25%,the total number of registers used is reduced by 23.02%,and the total block memory bits utilization is reduced by 20%.These results show that the proposed low-power design is an effective method.     

HORNLOG: A graph-based interpreter for general Horn clauses

This paper presents hornlog, a general Horn-clause proof procedure that can be used to interpret logic programs. The system is based on a form of graph rewriting, and on the linear-time algorithm for testing the unsatisfiability of propositional Horn formulae given by Dowling and Gallier [8]. hornlog applies to a class of logic programs which is a proper superset of the class of logic programs handled by PROLOG systems. In particular, negative Horn clauses used as assertions and queries consisting of disjunctions of negations of Horn clauses are allowed. This class of logic programs admits answers which are indefinite, in the sense that an answer can consist of a disjunction of substitutions. The method does not use the negation-by- failure semantics [6] in handling these extensions and appears to have an immediate parallel interpretation.     

On computability by logic programs

The problem of computational completeness of Horn clause logic programs is revisited. The standard results on representability of all computable predicates by Horn clause logic programs are not related to the real universe on which logic programs operate. SLD-resolution, which is the main mechanism to execute logic programs, may give answer substitutions with variables. As the main result we prove that computability by Horn clause logic programs is equivalent to standard computability over the Herbrand universe with variables. The semantics we use isS-semantics introduced by Falaschi et al. [3]. As an application of the main result we prove the existence of a metainterpreter for a sublanguage of real Prolog, written in the language of Horn clauses with the S-semantics. We also show that the traditional semantics of Prolog do not reflect its computational behavior from the viewpoint of recursion theory.This article is a revised version of [13]. The work was essentially done during author's visit to ECRC.     

A predicate-transition net model for parallel interpretation of logic programs

A predicate/transition net model for a subset of Horn clause logic programs is presented. The syntax, transformation procedure, semantics, and deduction process for the net model are discussed. A possible parallel implementation for the net model is described, which is based on the concepts of communicating processes and relations. The proposed net model offers a syntactical variant of Horn clause logic and has two distinctions from other existing schemes for the logic programs: representation formalism and the deduction method. The net model provides an approach towards the solutions of the separation of logic from control and the improvement of the execution efficiency through parallel processing for the logic programs. The abstract nature of the net model also lends itself to different implementation strategies.<>     

NKI中的本体、框架和逻辑理论

NKI(国家知识基础设施)是一个大规模知识库,它用框架来表示本体中的概念,用Hom逻辑程序作为自动推理.给出NKI中的本体、框架和逻辑理论的形式表示以及形式表示之间的转换,并证明如果将本体、框架和逻辑理论看作是3个范畴,则这些转换是这3个范畴之间的函子.这个结果保证了在NKI中,基于Horn逻辑程序的推理关于用本体和框架表示的知识库是正确的.     

优先归纳逻辑程序的极限行为

虽然对归纳逻辑程序的极限行为至今并没有深入的研究，但是通常在分析正在执行的增量式或在线归纳学习算法时，必须考虑这种程序的极限行为．某些归纳学习算法如果不考虑极限行为可能运行到最后会发生错误．如果给定一个递增的例子集合序列，一个归纳逻辑程序会产生一个相应的具有集合论极限的Horn逻辑程序序列，则此归纳逻辑程序是收敛的，并且如果该Horn逻辑程序序列关于例子集合序列的极限是极限正确的，则此归纳逻辑程序是极限正确的，还说明GOLEM系统不是极限正确的．为了解决这个问题，提出了一个极限正确的称为优先GOLEM系统的归纳逻辑系统，并证明了在一定的限制下，优先GOLEM系统的算法是极限正确的．     

Proof procedure and answer extraction in Petri net model of logicprograms

A proof procedure and answer extraction in a high-level Petri net model of logic programs is discussed. The logic programs are restricted to the Horn clause subset of first-order predicate logic and finite problems. The logic program is modeled by a high-level Petri net and the execution of the logic program or the answer extraction process in predicate calculus corresponds to a firing sequence which fires the goal transition in the net. For the class of the programs described above, the goal transition is potentially firable if an only if there exists a nonnegative T-invariant which includes the goal transition in its support. This is the main result proved. Three examples are given to illustrate in detail the above results     

Prological Language Processing

We describe a Prolog-based approach to the development of language processors (such as preprocessors, frontends, evaluators, tools for software modification and analysis). The design of the corresponding environment Laptob for prological language processing is outlined. Language processor definitions in Laptob are basically Prolog programs. The programs might contain grammars, that is, we consider logic grammars. The programs can be typed, and they can be higher-order. The adaptation and composition of the logic programs themselves is supported by meta-programming. The environment offers tool support for efficient scanning, testing, and application development based on a make-system. We report on recent and ongoing applications of the Prolog-based approach.     

SYGRAF: implementing logic programs in a database style

It is shown how Horn logic programs can be implemented using database techniques, namely, mostly bottom-up in combination with certain top-down elements (as opposed to the top-down implementations of logic programs prevailing so far). The proposed method is sound and complete. It easily lends itself to a parallel implementation and is free of nonlogical features like backtracking. As an extension to the common approach to deductive databases, function symbols are allowed to appear in programs, and it is shown that much of database query optimization can be applied to optimize logic programs. An important advantage of present approach is its ability to evaluate successfully many programs that terminate under neither pure top-down nor bottom-up evaluation strategies     

基于二型模糊逻辑的多线程数据竞争检测方法研究

多线程机制以其诸多优势在程序开发中被广泛使用,然而随着多线程软件规模的增长,程序中潜存着许多并发缺陷,最常见的并发缺陷是数据竞争和死锁。目前,针对这些并发缺陷的检测手段都无法处理线程时序的不确定性,无法处理运行时环境对线程时序的影响,同时也不能计算这些并发缺陷发生的概率并根据概率生成其处理优先级。针对以上问题,提出了一种基于二型模糊逻辑的多线程数据竞争检测方法。该方法将传统的多线程时序分析和缺陷检测方法作为预处理,考虑程序运行时环境因素对线程时序的影响,利用二型模糊逻辑和隐马尔科夫模型对待检测程序建模,计算待检测程序在某一系统负载下的时序概率,并根据时序概率生成时序缺陷处理优先级列表供软件开发人员参考。     

基于模型的Fuzzing测试脚本自动化生成

针对基于知识的Fuzzing测试技术存在脚本编写工作量大的问题,提出一种基于模型的Fuzzing测试脚本自 动生成方法。方法首先以高阶属性文法形式化地描述数据模型,获取统一的、与测试环境无关的数据格式描述;然后 依据文法模型,将样本解析为带格式知识的文法分析树;最后建立文法分析树与测试逻辑的关联关系,实现自动化的 测试脚本生成。实验结果表明,所提出的方法能够自动生成有效的测试脚本,并发现软件中潜在的安全漏洞。