Personalizing learning programs with X-Learn, an XML-based, “user-device” adaptive multi-agent system

In this paper we present X-Learn, an XML-based, multi-agent system for supporting “user-device” adaptive e-learning, i.e. e-learning activities which take into account the profile, past behaviour, preferences and needs of users, as well as the characteristics of the devices they use for these activities. X-Learn is characterized by the following features: (i) it is highly subjective, since it handles quite a rich and detailed user profile that plays a key role during the learning activities; (ii) it is dynamic and flexible, i.e. it is capable of reacting to variations in user exigencies and objectives; (iii) it is device-adaptive, since it decides the learning objects to present to the user on the basis of the device he is currently using; (iv) it is generic, i.e. it is capable of operating in a large variety of learning contexts; (v) it is XML based, since it exploits many facilities of XML technology for handling and exchanging information related to e-learning activities. The paper also reports various experimental results, as well as a comparison between X-Learn and other related e-learning management systems already presented in the literature.     

The end of the virus problem

Do you remember what it was like before viruses came along? You could get a disk, and just bung it in, no worries. Someone gave you a program, you'd just run it, no sweat. Someone sent you a document, you'd just read it on your word processor, you didn't have to take it to MIS to get it virus checked first. Do you remember those days? A lot of people do, but viruses have been around so long now, that a lot of people don't go back that far.     

Automatic transformation of iterative loops into recursive methods

ContextIn software engineering, taking a good election between recursion and iteration is essential because their efficiency and maintenance are different. In fact, developers often need to transform iteration into recursion (e.g., in debugging, to decompose the call graph into iterations); thus, it is quite surprising that there does not exist a public transformation from loops to recursion that can be used in industrial projects (i.e., it is automatic, it handles all kinds of loops, it considers exceptions, etc.).ObjectiveThis article describes an industrial algorithm implemented as a Java library able to automatically transform iterative loops into equivalent recursive methods. The transformation is described for the programming language Java, but it is general enough as to be adapted to many other languages that allow iteration and recursion.MethodWe describe the changes needed to transform loops of types while/do/for/foreach into recursion. We provide a transformation schema for each kind of loop.ResultsOur algorithm is the first public transformation that can be used in industrial projects and faces the whole Java language (i.e., it is fully automatic, it handles all kinds of loops, it considers exceptions, it treats the control statements break and continue, it handles loop labels, it is able to transform any number of nested loops, etc.). This is particularly interesting because some of these features are missing in all previous work, probably, due to the complexity that their mixture introduce in the transformation.ConclusionDevelopers should use a methodology when transforming code, specifically when transforming loops into recursion. This article provides guidelines and algorithms that allow them to face different problems such as exception handling. The implementation has been made publicly available as open source.     

A Monotonic On-Line Linear Algorithm for Hierarchical Agglomerative Classification

We start from an algorithm for on-line linear hierarchical classification for multidimensional data, using a centroid aggregation criterion. After evoking some real-life on-line settings where it can be used, we analyze it mathematically, in the framework of the Lance–Williams algorithms, proving that it does not have some useful properties: it is not monotonic, nor space-conserving. In order to use its on-line capabilities, we modify it and show that it becomes monotonic. While still not having the internal similarity-external dissimilarity property, the worst case classifications of the new algorithm are correctable with an additional small computational effort, on the overall taking O(n?k) time for n points and k classes. Experimental study confirm the theoretical improvements upon the initial algorithm. A theoretical and experimental comparison to other algorithms from the literature, shows that it is among the fastest and performs well.     

What software reality is really about

Software reality is more about people working together than it is about defined processes; it's more about science than it is about computer science; it's more about understanding than it is about documentation; it's more about inquiry than it is about metrics; it's more about skill than it is about methods; it's more about becoming better than it is about being good; and it's more about being good enough than it is about being right or wrong     

A grounding framework

In order for an agent to achieve its objectives, make sound decisions, communicate and collaborate with others effectively it must have high quality representations. Representations can encapsulate objects, situations, experiences, decisions and behavior just to name a few. Our interest is in designing high quality representations, therefore it makes sense to ask of any representation; what does it represent; why is it represented; how is it represented; and importantly how well is it represented. This paper identifies the need to develop a better understanding of the grounding process as key to answering these important questions. The lack of a comprehensive understanding of grounding is a major obstacle in the quest to develop genuinely intelligent systems that can make their own representations as they seek to achieve their objectives. We develop an innovative framework which provides a powerful tool for describing, dissecting and inspecting grounding capabilities with the necessary flexibility to conduct meaningful and insightful analysis and evaluation. The framework is based on a set of clearly articulated principles and has three main applications. First, it can be used at both theoretical and practical levels to analyze grounding capabilities of a single system and to evaluate its performance. Second, it can be used to conduct comparative analysis and evaluation of grounding capabilities across a set of systems. Third, it offers a practical guide to assist the design and construction of high performance systems with effective grounding capabilities.     

Bidder-anonymous English auction protocol based on revocable ring signature

Privacy has become a factor of increasing importance in auction design. This paper introduces an efficient and spontaneous privacy-preserving English auction protocol based on revocable ring signature. The proposed protocol has three appealing characteristic: first, it offers conditional privacy-preservation: while the auctioneer can verify that a bidder is an authorized participant in the system only the collaboration of auctioneer and registration manager can reveal the true identity of a malicious bidder. Second, it is one-time registration: the bidder can take part in plural auctions in one time registration. Third, it is spontaneous: the bidder can bid without interaction with the auctioneer and other bidders. Finally, it is efficient: it saves the communication round complexity comparing with previously proposed solutions.     

Recurrent Algorithms for Selecting the Maximum Input

In this paper, two novel recurrent algorithms for selecting the maxima of a set S containing M positive real numbers are introduced. In the first one the aim is to determine a threshold T such that only the maxima of S lie above it, while in the second one, each element of S is reduced independently of the rest until either it becomes zero (if it is non-maximum) or it freezes to a positive value (if it is a maximum). Convergence analysis of both schemes as well as neural network implementations of simplified versions of the algorithms are given. Finally, a comparison of the performance of the proposed algorithms with other related methods is carried out.     

基于口令的远程身份认证及密钥协商协议

基于口令的身份认证协议是研究的热点。分析了一个低开销的基于随机数的远程身份认证协议的安全性,指出了该协议的安全缺陷。构造了一个基于随机数和Hash函数、使用智能卡的远程身份认证和密钥协商协议：PUAKP协议。该协议使用随机数,避免了使用时戳带来的重放攻击的潜在风险。该协议允许用户自主选择和更改口令,实现了双向认证,有较小的计算开销;能够抵御中间人攻击;具有口令错误敏感性、口令的主机非透明性和强安全修复性;生成的会话密钥具有新鲜性、机密性、已知密钥安全性和前向安全性。     

Courseware abstraction: reducing development costs while producing qualitative improvements in CAL

Abstract Courseware abstraction is an approach to CAL whereby the lesson author creates a general parameterized CAL lesson that is then applied to many concrete examples. This approach has the following advantages over alternative approaches to lesson development: it is cost efficient; it facilitates lesson verification; it encourages the provision of as many examples as are desirable; it simplifies the selection of appropriate examples for presentation to each student; it provides a convenient framework for student evaluation, and it supports the development of factually exhaustive lessons. In short, it provides qualitative improvements, while at the same time reducing lesson development costs. Although widely used, courseware abstraction has not previously been identified as an important CAL technique and its relative merits have never received attention. In particular, there has been a failure to recognize that generative CAL derives most of its power from the use of courseware abstraction.     

What is rational about killing a patient with an overdose? Enlightenment,continental philosophy and the role of the human subject in system failure

This paper raises the issue of ergonomics' role in giving primacy to fully rational individual human actors in the creation of system failure, despite its commitment to see action as constrained by design and operational features of work. Reflecting on recent contributions to the journal, ergonomics' dilemma is considered against Enlightenment assumptions about individual human reason as the route to truth and goodness and its critics in continental philosophy. There is a pervasive, unstated pact here. What ergonomics chooses to call certain things (violations, errors, non-compliance, situation awareness) not only simultaneously affirms and denies full rationality on part of the people it studies, it also coincides with what the West sees as scientific, true and instrumental. Thus, ergonomics research legitimates its findings in terms it is expected to explain itself in. But by doing so, it reproduces the very social order it set out to repudiate.

Statement of Relevance: Ergonomics' choice of words (violations, errors, non-compliance) at once affirms and denies full rationality on part of the people it studies, reproducing the very social order it is meant to question and change.     

制图标准中剖切面后结构画法的探讨

针对机械制图标准中有关旋转剖视图画法的规定,围绕剖视图中剖切面后 结构的画法,提出了“剖切面后的其他结构”和“剖切结构及其有关部分”的具体界限,当一些 结构没有直接被剖切到时,若它所在的形体的轴线为两剖切面的交线,应按剖切面后的其他 结构,按原来的位置投射;否则应按照“剖切结构及其有关部分”,随其所在结构旋转到新的 位置,使画法进一步明确。针对有些学者建议,删去制图标准中“剖切面后面的其他结构, 应按原位置投射”的规定,认为不能删去,并证明了自己的观点。     

Ignoring data may be the only way to learn efficiently

Abstract

In designing learning algorithms it seems quite reasonable to construct them in a way such that all data the algorithm already has obtained are correctly and completely reflected in the hypothesis the algorithm outputs on these data. However, this approach may totally fail, i.e. it may lead to the unsolvability of the learning problem, or it may exclude any efficient solution of it. In particular, we present a natural learning problem and prove that it can be solved in polynomial time if and only if the algorithm is allowed to ignore data.     

Point in solid test for free-form solids defined with triangular Bézier patches

A new algorithm to study the fundamental point in solid test for free-form solids is presented. The test is performed efficiently and robustly because it does not use trigonometric functions and it makes it unnecessary to deal with complex special cases. The algorithm is based on considering the solid as composed of original tetrahedra and free-form cells, and it computes the test in two stages: evaluation of the point inclusion in these simple elements and merging of the results in a simple sum. The solid boundary is defined as a set of low-degree triangular Bézier patches.     

分组排序算法

提出了分组排序算法,详细分析了算法的原理及其时间与空间复杂度,得出了在最坏情况下的时间复杂度是θ（mn）;最好情况和平均情况下的时间复杂度均是θ（nlog（n/m^k））;在最坏情况下的空间复杂度是O（mn-m²＋m）;最好情况和平均情况下的空间复杂度均是O（m^klog（n/m^k））;并用多组随机数据与效率较高的快速算法进行仿真对比实验,试验结果说明了文中结论的正确性。这一结果,将有助于进一步设计高效的海量数据分析方法。     

The Value Proposition of Information Security: Putting The Pieces In Place

Abstract

Our privacy, if we value it, differs little from other treasures — fail to protect it and it is lost. The ability to protect information about us, i.e., to conduct our private lives, requires the ability to protect private communications (what I call transactional privacy) and the ability to protect personally identifiable information (PII) once it has been stored by a third party. Transactional privacy includes protection from unwarranted surveillance, wiretaps, or e-mail intercepts, and eavesdropping, whether intentional or coincidental.     

Generic multiset programming with discrimination-based joins and symbolic Cartesian products

This paper presents GMP, a library for generic, SQL-style programming with multisets. It generalizes the querying core of SQL in a number of ways: Multisets may contain elements of arbitrary first-order data types, including references (pointers), recursive data types and nested multisets; it contains an expressive embedded domain-specific language for specifying user-definable equivalence and ordering relations, extending the built-in equality and inequality predicates; it admits mapping arbitrary functions over multisets, not just projections; it supports user-defined predicates in selections; and it allows user-defined aggregation functions.     

Experimental Goal Regression: A Method for Learning Problem-Solving Heuristics

This research examines the process of learning problem solving with minimal requirements for a priori knowledge and teacher involvement. Experience indicates that knowledge about the problem solving task can be used to improve problem solving performance. This research addresses the issues of what knowledge is useful, how it is applied during problem solving, and how it can be acquired. For each operator used in the problem solving domain, knowledge is incrementally learned concerning why it is useful, when it is applicable, and what transformation it performs. The method of experimental goal regression is introduced for improving the learning rate by approximating the results of analytic learning. The ideas are formalized in an algorithm for learning and problem solving and demonstrated with examples from the domains of simultaneous linear equations and symbolic integration.     

GPS与北斗电离层延迟误差对比分析

在GPS与北斗的多系统定位中,使用双系统双频接收机,影响电离层延迟精度的主要因素是各系统导航电文中的电离层参数。由于电离层参数的不同,采用同一电离层时延模型计算得到的电离层延迟结果互不相同,造成时延精度的差异。利用GPS/北斗接收机进行观测,得到两系统的电离层参数,通过模型计算两系统在垂直方向的电离层延迟TEC,并将同一时刻、同一区域内的IGS电离层的TEC作为参考值来计算两系统的电离层时延精度。实验结果表明,GPS与北斗导航电文中的电离层参数存在较大差异,使得在同一地区、同一时刻两系统的计算结果出现较大差异,利用IGS参考值求其时延精度,GPS的电离层延迟精度较北斗系统要高。