一种交换协议的理性模型及其公平机制设计

理性交换协议是解决小额支付的有效方法,但是由于参与者的自利性,理性交换协议的公平性较难满足。论文首先对理性交换过程中的集体利益进行形式化定义,并基于占优策略构建理性参与者模型,以及基于占优策略和集体利益建立理性交换协议的公平性模型;其次基于激励相容理论设计理性交换协议的公平机制,基于理性交换协议的公平机制和扩展式博弈构建理性交换协议的理性博弈模型,并基于理性交换协议的博弈模型设计了一个理性交换协议;最后基于相关博弈方法证明所设计协议满足正确性和理性公平性,并用一个案例说明方案的可行性。     

公平的电子合同签署协议的博弈分析与改进

为了克服传统时序逻辑以封闭系统方式分析协议的缺点,根据电子合同签署协议的特点引入一种基于博弃的ATL逻辑形式化分析方法.利用该方法分析了一个公平的电子合同签署协议,发现该协议存在不满足公平性和时限性的缺陷.通过向协议中添加额外的时间控制信息和Abort子协议对该协议进行了改进,并使用Mocha模型检测工具以ATL公式和in-variant Checking相结合的方式对改进协议的公平性和时限性进行有效地验证.实验结果表明,改进后的协议满足公平性和时限性.     

基于动态博弈描述的电子商务协议公平性*

基于通信顺序进程和动态博弈理论对电子商务系统建模,提出了结构化的电子商务协议的公平性, 并基于该模型给出了公平性的形式化定义, 可以用于电子商务协议公平性的分析。与以往工作相比,主要贡献在于：a)系统模型中的失效模型分别对进程和通信失效建模,增加了通信延迟失效模型,可以分析系统失效时满足的公平性; b)收益平衡从参与者获得利益和损失利益两个角度定义公平性,打破了以往公平性定义只能应用于零和交易系统的局限; c)结构化的公平性分别考虑系统诚实参与者中途自愿退出或者因失效中止协议的公平性和有参与者欺骗下的协议的公平性等。后两点解决了系统满足公平性定义但实际上对参与者不公平的矛盾.     

一种新的电子商务协议分析方法

基于卿-周逻辑给出了一些新的逻辑推理规则,并提出了一种扩展的通信有限状态自动机,用于分析电子商务协议的安全性质.该方法可描述协议参与者的行为与知识,且无需人为地引入初始假设.对扩展模型抽象并修改后,还可验证其它一些与加密、签名消息无关的性质.利用该方法分析了匿名可恢复的公平交换协议,发现其满足有效性、公平性、可追究性,但不满足匿名性,并用UPPAAL验证了协议的公平性、活性与时效性等.     

一种可靠的多方不可否认协议的逻辑分析方法

多方不可否认协议需要满足不可否认性、公平性和时限性三大安全目标,但是现有的对多方不可否认协议的形式化分析方法大多是对两方协议分析方法的简单扩展,单一方法不能完整覆盖所有的安全目标分析;同时,对单一安全目标的分析能力有限,分析结果不可靠。首先,综合比较现有的分析技术,选定SVO逻辑进行扩展,显式引入时间因素,给出对应的语法定义和时间演算公理。然后,对改进逻辑的语义模型进行介绍,并证明了逻辑系统的可靠性,使得改进后的逻辑系统支持对多方不可否认协议三大安全目标的分析。最后,选取一个典型的多方不可否认协议,分别对其时限性和公平性进行分析,发现了其中存在的时限性和公平性缺陷,并给出了对应的攻击方法。其中,公平性缺陷是首次被发现。     

一种乐观电子商务协议的公平性分析

乐观电子商务协议通常具有复杂结构,由多个子协议组合而成,与传统认证协议具有显著不同。电子商务协议最主要目的是实现买卖双方的公平交换,同时假定交换双方都可能是不诚实的,需要考虑来自协议合法实体的内部攻击。文章在深入分析公平交换协议各项属性的基础上,定义了电子项的认证属性,对SVO逻辑进行了扩展,使用SVO逻辑语法定义了电子商务协议应满足的公平性。文章以一种真实的电子商务协议为对象,演示了基于SVO逻辑的电子商务协议公平性分析方法,并指出该协议存在安全缺陷,提出改进意见。     

有穷机和逻辑结合的电子商务协议分析方法

提出一种扩展的有穷自动机模型,并结合卿-周逻辑给出一种新的电子商务协议形式化分析方法,用于分析电子商务协议的可追究性、公平性和时限性.该方法结合了模型检测和逻辑分析两种形式化分析方法的优点,可以准确形象地描述协议的具体运行过程,并且在发生重放攻击时能够正确分析各方的责任.利用该方法对Kim等人提出的改进版ZG协议进行了实例分析,给出了描述该协议运行过程的状态转换图,结合状态转换图对该协议分析得出其满足可追究性、公平性、时限性,并且不存在被重放攻击的可能.最后用时间自动机UPPAAL验证了新方法中有穷自动机模型的准确性和时限性分析的有效性.     

乐观公平交换协议的可追究性分析

可追究性是安全电子商务协议必须遵循的重要原则之一,乐观公平交换协议是一类重要的电子商务协议。目前没有针对乐观公平交换协议的可追究性进行形式化分析的具体方法。文章提出了一种分析乐观公平交换协议可追究性的形式化方法,该方法不再单独定义非否认证据,只是研究协议的目标设计是否能提供实现可追究性的证据,将可追究性证明与公平性等其它安全性质的证明分开讨论,这样不论协议是否满足其它安全性质,都可以讨论协议是否满足可追究性。     

不可否认协议分析的扩展ZQZ逻辑方法

不可否认协议必须满足存活性、不可否认性、公平性和时限性,但当前大多数形式化方法只能分析该类协议的部分性质,证明或证伪协议逻辑的部分正确性.本文通过向ZQZ逻辑添加时间表达式,提出了一种适用于不可否认协议建模与分析的扩展ZQZ逻辑方法,包括推理规则和安全性质模型.展示新方法的应用时,使用其分析了ZG和KPB这两个局部逻辑...     

一种理性安全协议的博弈逻辑描述模型

博弈逻辑ATL和ATEL可以对传统安全协议的公平性、安全性等性质进行分析与验证。但在理性环境中,由于参与者对知识的自利性,ATL和ATEL都不能形式化分析与验证理性安全协议。因此在CEGS中引入效用函数和偏好关系知识,得到新的rCEGS,并在合作模态算子《Γ》中加入行为ACT参数,提出新的可形式化分析理性安全协议的交替时序认知逻辑rATEL-A。然后运用rATEL-A构建两方理性安全协议的形式化模型,并基于rCEGS的等价扩展式博弈,对具体的两方理性交换协议进行形式化分析,结果表明构建的形式化模型可以有效地形式化分析理性安全协议的正确性、理性安全性和理性公平性。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.