Properties of a predicate transformer of the VRS system

Models specified in the language of basic protocols are considered. These models are attribute transition systems, and their states are defined by formulas of multisort first-order predicate calculus over system attributes. Attributes of simple numeric and symbolic types, functional types, and queues are allowed. Assignment operators, queue update operators, and arbitrary formulas are used in postconditions of basic protocols. To pass from one state to another, a predicate transformer is constructed as a function of formula transformation. The following main property of the predicate transformer is proved: it calculates the strongest postcondition for symbolic states.     

一种基于关系矩阵的信息系统属性约简算法

提出了一种新的信息系统属性约简算法。为此,首先建立了信息系统与关系矩阵之间的联系;其次,从关系矩阵的角度研究了合理刻画属性重要性的新指标;然后利用新指标作为启发式信息设计了一种新的属性约简算法。与现有算法相比,该算法具有较大的灵活性,它能从搜索空间中逐次删除不重要属性,避免对其重要性的重复计算。此外,对该算法的时间复杂度进行了详细的分析,并通过实例和实验验证它的可行性与有效性。     

Refinement is complete for implementations

Modal transition systems specify sets of implementations, their refining labelled transition systems, through Larsen & Thomsen’s co-inductive notion of refinement. We demonstrate that refinement precisely captures the identification of a modal transition system with its set of implementations: refinement is reverse containment of sets of implementations. This result extends to models that combine state and event observables and is drawn from a SFP-domain whose elements are equivalence classes of modal transition systems under refinement [HJS04], and abstraction-based finite-model properties proved in this paper. As a corollary, validity checking is model checking for Hennessy-Milner formulas that characterize modal transition systems with bounded computation paths. We finally sketch how techniques developed in this paper can be used to detect inconsistencies between multiple modal transition systems and, if consistent, to verify properties of all common implementations.Received January 2004Revised August 2004Accepted December 2004 by M. Leuschel and D. J. Cooke     

生成诊断公式的有限状态进程等价验证

分析有限状态进程互模拟等价判定技术,探讨了诊断公式的生成问题.给出了将有限状态进程转化为带标号的迁移系统,修改了Paige和Trajan求解最粗划分的算法,使其适用于带标号的迁移系统.给出生成Hennessy-Milner逻辑描述的诊断公式的算法,当两个进程不能互模拟时,产生两个诊断公式.算法的时间复杂度为O(m log n),空间复杂度为O(m+n).     

Compiling and verifying SC-SystemJ programs for safety-critical reactive systems

Most of today's embedded systems are very complex. These systems, controlled by computer programs, continuously interact with their physical environments through network of sensory input and output devices. Consequently, the operations of such embedded systems are highly reactive and concurrent. Since embedded systems are deployed in many safety-critical applications, where failures can lead to catastrophic events, an approach that combines mathematical logic and formal verification is employed in order to ensure correct behavior of the control algorithm. This paper presents What You Prove Is What You Execute (WYPIWYE) compilation strategy for a Globally Asynchronous Locally Synchronous (GALS) programming language called Safey-Critical SystemJ. SC-SystemJ is a safety-critical subset of the SystemJ language. A formal big-step transition semantics of SC-SystemJ is developed for compiling SC-SystemJ programs into propositional Linear Temporal Logic formulas. These LTL formulas are then converted into a network of Mealy automata using a novel and efficient compilation algorithm. The resultant Mealy automata have a straightforward syntactic translation into Promela code. The resultant Promela models can be used for verifying correctness properties via the SPIN model-checker. Finally there is a single translation procedure to compile both: Promela and C/Java code for execution, which satisfies the De-Bruijn index, i.e. this final translation step is simple enough that is can be manually verified.     

The order of merging operations for queries in inverted file systems

In inverted file systems, queries can be written as Boolean expressions of inverted attributes. In response to a query, the system accesses address lists associated with the attributes in the query, merges them, and selects those records that satisfy the search logic. In this paper we consider the minimization of the CPU time needed for the merging operation. The time can possibly be reduced by taking address lists that occur in several product terms as a common factor of these products. This means that the union operation must be performed before the intersection operation. We present formulas which can be used to decide whether the above method is advantageous. The time can also be reduced by choosing the order of intersection operations so that it takes into consideration the occurrences of the address lists in the products and the lengths of the address lists. For choosing the order of intersection operations we give a heuristic algorithm that minimizes the total time needed for intersections.     

Quantifier-free encoding of invariants for hybrid systems

Hybrid systems are a clean modeling framework for embedded systems, which feature integrated discrete and continuous dynamics. A well-known source of complexity comes from the time invariants, which represent an implicit quantification of a constraint over all time points of a continuous transition. Emerging techniques based on Satisfiability Modulo Theory (SMT) have been found promising for the verification and validation of hybrid systems because they combine discrete reasoning with solvers for first-order theories. However, these techniques are efficient for quantifier-free theories and the current approaches have so far either ignored time invariants or have been limited to hybrid systems with linear constraints. In this paper, we propose a new method that encodes a class of hybrid systems into transition systems with quantifier-free formulas. The method does not rely on expensive quantifier elimination procedures. Rather, it exploits the sequential nature of the transition system to split the continuous evolution enforcing the invariants on the discrete time points. This way, we can encode all hybrid systems whose invariants can be expressed in terms of polynomial constraints. This pushes the application of SMT-based techniques beyond the standard linear case.     

Similarity computing model of high dimension data for symptom classification of Chinese traditional medicine

In recent years, researchers have paid more and more attention on data mining of practical applications. Aimed to the problem of symptom classification of Chinese traditional medicine, this paper proposes a novel computing model based on the similarities among attributes of high dimension data to compute the similarity between any tuples. This model assumes data attributes as basic vectors of m dimensions and each tuple as a sum vector of all the attribute-vectors. Based on the transcendental concept similarity information among attributes, it suggests a novel distance algorithm to compute the similarity distance of any pair of attribute-vectors. In this method, the computing of similarity between any tuples are turned to the formulas of attribute-vectors and their projections of each other, and the similarity between any pair of tuples can be worked out by computing these vectors and formulas. This paper also presents a novel classification algorithm based on the similarity computing model and successfully applies the algorithm into the symptom classification of Chinese traditional medicine. The efficiency of the algorithm is proved by extensive experiments.     

反应系统的连续时序逻辑表示和验证

引进一个称为LTLC的连续时间时序逻辑，用来对反应系统进行规范与验证．LTLC的一个重要特点是它能在统一的逻辑框架下表示反应系统及其性质，这样就可将系统与性质问的满足关系转化为逻辑公式间的蕴涵关系．同时，采用非负实数集作为时间域还使我们可以利用标准的存在量词来表示变量隐藏，并可用逻辑蕴涵来表示反应系统间的求精关系．该文首先给出了LTLC的一个简单介绍，然后讨论了如何使用LTLC对反应系统进行表示与推理，最后证明了一个关于LTLC的可判定性结果．此结果可用于有穷状态反应系统的自动验证．     

A method for the synthesis of controllers to handle safety,liveness, and real-time constraints

Describes a synthesis method that automatically derives controllers for timed discrete-event systems with nonterminating behavior modeled by timed transition graphs and specifications of control requirements expressed by metric temporal logic (MTL) formulas. Synthesis is performed by using: 1) a forward-chaining search that evaluates the satisfiability of MTL formulas over sequences of states generated by occurrences of actions and 2) a control-directed backtracking technique that takes into consideration the controllability of actions. This method has several interesting features. First, the issues of controllability, safety, liveness, and real time are integrated in a single framework. Second, the synthesis process does not require explicit storage of an entire transition structure over which formulas are checked and can be stopped at any moment, giving an approximate but useful result. Third, search and control mechanisms allow circumvention of the state explosion problem     

Information systems in modeling interactive computations on granules

In this paper, we discuss the importance of information systems in modeling interactive computations performed on (complex) granules and we propose a formal approach to interactive computations based on generalized information systems and rough sets which can be combined with other soft computing paradigms such as fuzzy sets or evolutionary computing, but also with machine learning and data mining techniques. Information systems are treated as dynamic granules used for representing the results of the interaction of attributes with the environment. Two kinds of attributes are distinguished, namely, the perception attributes, including sensory attributes, and the action attributes. Sensory attributes are the basic perception attributes, other perception attributes are constructed on the basis of the sensory ones. Actions are activated when their guards, being often complex and vague concepts, are satisfied to a satisfactory degree. The guards can be approximated on the basis of measurements performed by sensory attributes rather than defined exactly. Satisfiability degrees for guards are results of reasoning called the adaptive judgment. The approximations are induced using hierarchical modeling. We show that information systems can be used for modeling more advanced forms of interactions in hierarchical modeling. The role of hierarchical interactions is emphasized in the modeling of interactive computations. Some illustrative examples of interactions used in the ACT-R 6.0 system are reported. ACT-R 6.0 is based on a cognitive architecture and can be treated as an example of a highly interactive complex granule which can be involved in hierarchical interactions. For modeling of interactive computations, we propose much more general information systems than the studied dynamic information systems (see, e.g., Ciucci (2010) [8] and Pa?asiński and Pancerz (2010) [32]). For example, the dynamic information systems are making it possible to consider incremental changes in information systems. However, they do not contain the perception and action attributes necessary for modeling interactive computations, in particular for modeling intrastep interactions.     

基于邻域粒化的混合信息系统动态规则提取

现有的混合信息系统知识发现模型涵盖的数据类型大多为符号型、数值型条件属性及符号型决策属性,且大多数模型的关注点是属性约简或特征选择,针对规则提取的研究相对较少。针对涵盖更多数据类型的混合信息系统构建一个动态规则提取模型。首先修正了现有的属性值距离的计算公式,对错层型属性值的距离给出了一种定义形式,从而定义了一个新的混合距离。其次提出了针对数值型决策属性诱导决策类的3种方法。其后构造了广义邻域粗糙集模型,提出了动态粒度下的上下近似及规则提取算法,构建了基于邻域粒化的动态规则提取模型。该模型可用于具有以下特点的信息系统的规则提取： （1）条件属性集可包括单层符号型、错层符号型、数值型、区间型、集值型、未知型等; （2）决策属性集可包括符号型、数值型。利用UCI数据库中的数据集进行了对比实验,分类精度表明了规则提取算法的有效性。     

Clustering factor estimation for totally clustered attributes

Cost models based on the clustering factor (CF) of the attributes have been proposed and shown to be attractive for block access estimation in databases, thanks to their accuracy and economy of use. While query optimizers can use the actual CFs, measured from the data, physical design methods and tools must rely on estimates before the data are stored.

In this paper we present a CF estimation procedure which can be applied to totally clustered attributes (e.g. ordered attributes). Simple and accurate approximations of the derived formulas are also introduced.

Simulations show the accuracy of the proposed CF estimates and the improvment in their behaviour compared to previously published estimates. Reliability for physical design of cost models based on the CF in the presence of a skewed data distribution is also discussed.     

基于IOWA-DEA方法的理想软件产品方案选择研究

针对理想软件产品方案选择研究中的不足,文章将单个顾客用多粒度语言来描述的软件产品功能需求属性重要度进行基本语言术语(BLTS)转换,在此基础上引进诱导有序加权平均(IOWA)算子来确定某类顾客对于软件产品所有的产品功能需求属性重要度的评价值;根据各软件产品方案的工程属性特征值运用数据包络分析(DEA)方法来确定各软件产品方案的排名权值;运用效用值法将基于不同需求因素的软件产品方案排名决策信息进行转换,再采用互补判断矩阵中的排序公式来选择最贴近某类顾客需求的理想软件产品方案。最后给出了算法释例。     

On the specification of modal systems: A comparison of three frameworks

This paper studies the relationships between three notions of behavioural preorder that have been proposed in the literature: refinement over modal transition systems, and the covariant–contravariant simulation and the partial bisimulation preorders over labelled transition systems. It is shown that there are mutual translations between modal transition systems and labelled transition systems that preserve, and reflect, refinement and the covariant–contravariant simulation preorder. The translations are also shown to preserve the modal properties that can be expressed in the logics that characterize those preorders. A translation from labelled transition systems modulo the partial bisimulation preorder into the same model modulo the covariant–contravariant simulation preorder is also offered, together with some evidence that the former model is less expressive than the latter. In order to gain more insight into the relationships between modal transition systems modulo refinement and labelled transition systems modulo the covariant–contravariant simulation preorder, their connections are also phrased and studied in the context of institutions.     

A statistical approach to knowledge acquisition for expert systems

Classical expert systems are rule based, depending on predicates expressed over attributes and their values. In the process of building expert systems, the attributes and constants used to interpret their values need to be specified. Standard techniques for doing this are drawn from psychology, for instance, interviewing and protocol analysis. This paper describes a statistical approach to deriving interpreting constants for given attributes. It is also possible to suggest the need for attributes beyond those given.The approach for selecting an interpreting constant is demonstrated by an example. The data to be fitted are first generated by selecting a representative collection of instances of the narrow decision addressed by a rule, then making a judgement for each instance, and defining an initial set of potentially explanatory attributes. A decision rule graph plots the judgements made against pairs of attributes. It reveals rules and key instances directly. It also shows when no rule is possible, thus suggesting the need for additional attributes. A study of a collection of seven rule based models shows that the attributes defined during the fitting process improved the fit of the final models to the judgements by twenty percent over models built with only the initial attributes.     

唇同步的自动识别与验证研究

唇同步效果影响人类对语言的理解。着重研究汉语语音和口型的唇同步，将汉语对应口型划分为4类、两种状态(极点态与过渡态)，得出汉语唇同步验证是对极点态音频和极点态视频的同步验证，提出基于极点态音频／视频知识库的唇同步识别与验证模型，分别阐述了模型中音频／视频特征分析子系统，提出了可以将基于运动对象识别的帧间差法与嘴唇形状、颜色和运动特征结合，实现嘴唇精确定位，最后给出唇同步验证过程。     

特征加权的模糊C聚类算法

参照文献[5]中将K-means聚类算法与特征权重优化相结合的方法,推导出FCM聚类算法与特征权重优化相结合的优化迭代公式,形成加权FCM算法.将加权FCM算法中计算聚类均值项的公式代入到计算隶属度的更新公式和特征权重的更新公式中,得到加权FCM扩展算法.由于这个扩展算法消去了均值项,它对于有序属性和无序类别属性的隶属度和特征权重的更新公式具有统一的形式,因此可以很方便地应用到混合属性数据集的加权聚类分析中来.该算法的收敛性分析与FCM类似,算法迭代结束后能给出一组优化的特征权重值.仿真实验结果与WKMeans算法的结果基本一致,说明该方法在优化混合属性数据集的特征权重时是有效的.     

Developmental systems with locally catenative formulas

Summary A locally catenative sequence of strings of letters is such that each string in the sequence, after an initial stretch, is formed by concatenating strings which occurred at some specified distances previously in the sequence. These kinds of structures are frequently encountered in biological development, particularly in the case of compound branching structures or compound leaves. Developmental systems have been formally defined in previous publications. One of the present results is that dependent PDOL systems can produce sequences for every locally catenative formula (PDOL systems are propagating, deterministic developmental systems without interactions). Every dependent PDOL system produces a sequence which satisfies an infinite class of locally catenative formulas. Some of these formulas can be derived from a minimum formula, but a sequence may satisfy more than one minimum formulas.