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ISSN 1000-9000(Print)
CN 11-2296/TP
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Edited by: Editorial Board of Journal Of Computer Science and Technology
P.O. Box 2704, Beijing 100190, P.R. China
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  • Table of Content
      15 January 2001, Volume 16 Issue 1 Previous Issue    Next Issue
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    Investigation on AQ11,ID3 and the Principle of Discernibility Matrix
    WANG Jue(王珏),GUI Jia(崔佳)and ZHAO Kai(赵凯)
    Journal of Computer Science and Technology, 2001, 16 (1): 0-0. 
    Abstract   PDF(327KB) ( 2206 )   Chinese Summary
    The principle of discernibility matrix serves as a tool to discuss and analyze two algorithms of traditional inductive machine learning, AQ11 and ID3. The results are: (1) AQ11 and its family can be completely specified by the principle of discernibility matrix; (2) ID3 can be partly, but not naturally, specified by the principle of discernibility matrix; and (3) The principle of discernibility matrix is employed to analyze Cendrowska sample set, and it shows the weaknesses of knowledge representation style of decision tree in theory.
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    An Improved Error Handling Method in SNMPv2 Protocol Operations
    XU Guanghui(胥光辉),XIE Xiren(谢希仁)and XU Yongsen(徐永森)
    Journal of Computer Science and Technology, 2001, 16 (1): 0-0. 
    Abstract   PDF(211KB) ( 1853 )   Chinese Summary
    SNMPv1 is very successful due to its simplicity, flexibility, and extensibility. However, simplicity can also be a drawback. In SNMPv1, a manager can only retrieve one piece of information at a time, and an agent merely reports one error to its manager, though there may be several errors having occurred during the protocol operation. These two interactions enlarge the number of protocol exchanges between a manager and an agent. SNMPv2 permits the retrieval of large data blocks, but the errors can only be handled one by one. These errors continually occur in a multivendor network. This paper proposes an error handling method in SNMPv2 protocol operations. In this method, all errors within a received PDU can be detected by the agent simultaneously.
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    Semantics of Constructions(Ⅰ) — The Traditional Approach
    FU Yuxi(傅育熙)
    Journal of Computer Science and Technology, 2001, 16 (1): 0-0. 
    Abstract   PDF(466KB) ( 1268 )   Chinese Summary
    It is well known that impredicative type systems do not have set theoretical semantics. This paper takes a look at semantics of inductive types in impredicative type systems. A generalized inductive type is interpreted as an omega set generated by effectivizing a certain rule set. The result provides a semantic justification of inductive types in the calculus of constructions.
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    A Non-Blocking Locking Method and Performance Evaluation on Network of Workstations
    YU Ge(于戈),WANG Guoren(王国仁)and ZHENG Huaiyuan(郑怀远)
    Journal of Computer Science and Technology, 2001, 16 (1): 0-0. 
    Abstract   PDF(407KB) ( 1655 )   Chinese Summary
    A network of workstation (NOW) can act as a single and scalable powerful computer by building a parallel and distributed computing platform on top of it. WAKASHI is such a platform system that supports persistent object management and makes full use of resources of NOW for high performance transaction processing. One of the main difficulties to overcome is the bottleneck caused by concurrency control mechanism. Therefore, a non-blocking locking method is designed, by adopting several novel techniques to make it outperform the other typical locking methods such as 2PL: 1) an SDG (Semantic Dependency Graph) based non-blocking locking protocol for fast transaction scheduling; 2) a massively virtual memory based backup-page undo algorithm for fast restart; and 3) a multi-processor and multi-thread based transaction manager for fast execution. The new mechanisms have been implemented in WAKASHI and the performance comparison experiments with 2PL and DWDL have been done. The results show that the new method can outperform 2PL and DWDL under certain conditions. This is meaningful for choosing effective concurrency control mechanisms for improving transaction processing performance in NOW environments.
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    Verifying Time Petri Nets by Linear Programming
    LI Xuandong(李宣东)
    Journal of Computer Science and Technology, 2001, 16 (1): 0-0. 
    Abstract   PDF(282KB) ( 1387 )   Chinese Summary
    The paper proposes an approach to solving some verification problems of time Petri nets using linear programming. The approach is based on the observation that for loop-closed time Petri nets, it is only necessary to investigate a finite prefix of an untimed run of the underlying Petri net. Using the technique the paper gives solutions to reachability and bounded delay timing analysis problems. For both problems algorithms are given, that are decision procedures for loop-closed time Petri nets, and semi-decision procedures for general time Petri nets.
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    Guidelines for Creating a Rule-Based Knowledge Learning System and Their Application to a Chinese Business Card Layout Analysis
    PAN Wumo(潘武模)and WANG Qingren(王庆人)
    Journal of Computer Science and Technology, 2001, 16 (1): 0-0. 
    Abstract   PDF(301KB) ( 1554 )   Chinese Summary
    Rule selection has long been a problem of great challenge that has to be solved when developing a rule-based knowledge learning system. Many methods have been proposed to evaluate the eligibility of a single rule based on some criteria. However, in a knowledge learning system there is usually a set of rules. These rules are not independent, but interactive. They tend to affect each other and form a rule-system. In such case, it is no longer reasonable to isolate each rule from others for evaluation. A best rule according to certain criterion is not always the best one for the whole system. Furthermore, the data in the real world from which people want to create their learning system are often ill-defined and inconsistent. In this case, the completeness and consistency criteria for rule selection are no longer essential. In this paper, some ideas about how to solve the rule-selection problem in a systematic way are proposed. These ideas have been applied in the design of a Chinese business card layout analysis system and gained a good result on the training data set of 425 images. The implementation of the system and the result are presented in this paper.
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    A New Mesh Simplification Algorithm Based on Triangle Collapses
    PAN Zhigeng(潘志庚),ZHOU Kun(周昆)and SHI Jiaoying(石教英)
    Journal of Computer Science and Technology, 2001, 16 (1): 0-0. 
    Abstract   PDF(276KB) ( 3136 )   Chinese Summary
    In this paper a new mesh simplification algorithm based on triangle collapses is presented. The algorithm can provide efficient error management and simplify the original mesh greatly. Progressive meshes may be constructed with triangle collapsing operation. To make continuous transition between level of detail (LOD) models possible, a method for interpolating is also presented. Examples illustrate the efficiency of the algorithm.
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    Towards a Denotational Semantics of Timed RSL Using Duration Calculus
    LI Li(李黎)
    Journal of Computer Science and Technology, 2001, 16 (1): 0-0. 
    Abstract   PDF(333KB) ( 1508 )   Chinese Summary
    The Timed RAISE Specification Language (Timed RSL) is an extension of RAISE Specification Language by adding time constructors for specifying real-time applications. Duration Calculus (DC) is a real-time interval logic which can be used to specify and reason about timing and logical constraints on duration properties of Boolean states in a dynamic system. This paper gives a denotational semantics to a subset of Timed RSL expressions, using Duration Calculus extended with super-dense chop modality and notations to capture time point properties of piecewise continuous states of arbitrary types. Using this semantics, the paper presents a proof rule for verifying Timed RSL iterative expressions and implements the rule to prove the satisfaction by a sample Timed RSL specification of its real-time requirements.
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    Extending the Cooper Minimal Pair Theorem
    ZHANG Zaiyue(张再跃)
    Journal of Computer Science and Technology, 2001, 16 (1): 0-0. 
    Abstract   PDF(299KB) ( 1184 )   Chinese Summary
    In the study of cappable and noncappable properties of the recursively enumerable (r.e.) degrees, Lempp suggested a conjecture which asserts that for all r.e. degrees a and b, if a!=b then there exists an r.e. degree c such that c<=a and c!=b and c is cappable. We shall prove in this paper that this conjecture holds under the condition that a is high. Working below a high r.e. degree h, we show that for any r.e. degree b with h!=b, there exist r.e. degrees a0 and a1 such that a0,a1 !=b, a0,a1<=h, a0 and a1 form a minimal pair.
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    Fuzzy Association Degree with Delayed Time in Temporal Data Model
    LIU Weiyi(刘惟一),GUO Lingzhi(郭陵芝)and SONG Ning(宋宁)
    Journal of Computer Science and Technology, 2001, 16 (1): 0-0. 
    Abstract   PDF(240KB) ( 1167 )   Chinese Summary
    This paper presents an expression of the semantic proximity. Based on the temporal data model, a method of the temporal approximation is given. Using these concepts, we provide an evaluated method of fuzzy and dynamic association degree with delayed time and a superposition method of association degrees. Particularly, by means of the fuzzy and dynamic association degree, we can discover the connection between the weather data of two regions.
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ISSN 1000-9000(Print)

CN 11-2296/TP

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Journal of Computer Science and Technology
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