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1.
Partial evaluation of Maple   总被引:1,自引:0,他引:1  
Having been convinced of the potential benefits of partial evaluation, we wanted to apply these techniques to code written in Maple, our Computer Algebra System of choice. Maple is a very large language, with a number of non-standard features. When we tried to implement a partial evaluator for it, we ran into a number of difficulties for which we could find no solution in the literature. Undaunted, we persevered and ultimately implemented a working partial evaluator with which we were able to very successfully conduct our experiments, first on small codes, and now on actual routines taken from Maple’s own library. Here, we document the techniques we had to invent or adapt to achieve these results.  相似文献   

2.
As developers of libraries implementing interval arithmetic, we faced the same difficulties when it comes to testing our libraries. What must be tested? How can we devise relevant test cases for unit testing? How can we ensure a high (and possibly 100%) test coverage? Before considering these questions, we briefly recall the main features of interval arithmetic and of the IEEE 1788-2015 standard for interval arithmetic. After listing the different aspects that, in our opinion, must be tested, we contribute a first step towards offering a test suite for an interval arithmetic library. First we define a format that enables the exchange of test cases, so that they can be read and tried easily. Then we offer a first set of test cases, for a selected set of mathematical functions. Next, we examine how the Julia interval arithmetic library, IntervalArithmetic.jl, actually performs to these tests. As this is an ongoing work, we list extra tests that we deem important to perform.  相似文献   

3.
In this work, we introduce a new framework able to deal with a reasoning that is at the same time non monotonic and uncertain. In order to take into account a certainty level associated to each piece of knowledge, we use possibility theory to extend the non monotonic semantics of stable models for logic programs with default negation. By means of a possibility distribution we define a clear semantics of such programs by introducing what is a possibilistic stable model. We also propose a syntactic process based on a fix-point operator to compute these particular models representing the deductions of the program and their certainty. Then, we show how this introduction of a certainty level on each rule of a program can be used in order to restore its consistency in case of the program has no model at all. Furthermore, we explain how we can compute possibilistic stable models by using available softwares for Answer Set Programming and we describe the main lines of the system that we have developed to achieve this goal.  相似文献   

4.
We devise a feature selection method in terms of a follow-out utility of a special classification procedure. In turn, we root the latter on binary features which we extract from the input patterns with a wrapper method. The whole contrivance results in a procedure that is progressive in two respects. As for features, first we compute a very essential representation of them in terms of Boolean independent components in order to reduce their entropy. Then we reverse the representation mapping to discover the subset of the original features supporting a successful classification. As for the classification, we split it into two less hard tasks. With the former we look for a clustering of input patterns that satisfies loose consistency constraints and benefits from the conciseness of binary representation. With the latter we attribute labels to the clusters through the combined use of basically linear separators.We implement out the method through a relatively quick numerical procedure by assembling a set of connectionist and symbolic routines. These we toss on the benchmark of feature selection of DNA microarray data in cancer diagnosis and other ancillary datasets.  相似文献   

5.
数据仓库中的数据集成转换   总被引:2,自引:0,他引:2  
本文首先提出了数据仓库中数据集成的一个总体框架,然后列举了在数据转换中可能遇到的主要问题,最后根据这些转换规则,给出了一种描述性脚本语言来描述这些规则,继而给相应的处理模块解析处理。  相似文献   

6.
In this paper, we shall propose a scheme for anonymous multicast and reception. Since the scheme can hide the identity of the receiver, we can resist the attack of traffic analysis. Besides that, we shall also extend our method to anonymous multicast. In our new scheme of multicast, we shall propose a new idea for seeds distribution that can also be applied to anonymous reception of messages.On top of all those above, in this paper, we shall reveal how we have solved the problem of synchronization, which is quite an accomplishment in a massive network, a new altitude that has never been reached.  相似文献   

7.
电梯规划的动态模型   总被引:2,自引:0,他引:2  
讨论了写字楼上下班高峰期的电梯规划问题。首先提出了电梯方案的衡量标准,然后建立了一个比较完整的“动态规划”模型,对模型进行了求解。最后,对结果作了进一步的讨论,讨论了该模型对一般建筑以及超高建筑规划时候结果的不同,并回过头来验证了衡量标准的正确性。最后根据一个实际问题给出解决的方案。  相似文献   

8.
In this paper we discuss reasoning about reasoning in a multiple agent scenario. We consider agents that are perfect reasoners, loyal, and that can take advantage of both the knowledge and ignorance of other agents. The knowledge representation formalism we use is (full) first order predicate calculus, where different agents are represented by different theories, and reasoning about reasoning is realized via a meta-level representation of knowledge and reasoning. The framework we provide is pretty general: we illustrate it by showing a machine checked solution to the three wisemen puzzle. The agents' knowledge is organized into units: the agent's own knowledge about the world and its knowledge about other agents are units containing object-level knowledge; a unit containing meta-level knowledge embodies the reasoning about reasoning and realizes the link among units. In the paper we illustrate the meta-level architecture we propose for problem solving in a multi-agent scenario; we discuss our approach in relation to the modal one and we compare it with other meta-level architectures based on logic. Finally, we look at a class of applications that can be effectively modeled by exploiting the meta-level approach to reasoning about knowledge and reasoning.  相似文献   

9.
施荣华  周玉  胥磊 《计算机工程与应用》2006,42(27):112-113,146
文章对一类群签名方案提出了一个通用的联合攻击,并将其应用于三个新提出的群签名方案,证明了这三个方案均是不安全的。其次,总结了此类方案的共性,分析了它们易受联合攻击的原因并提出了一种新的能抵抗联合攻击的体制,将这种体制用于群签名方案的构造过程中将使方案具有抗联合攻击性。最后,应用该体制,给出了一个安全的群签名方案。  相似文献   

10.
In this paper we begin by discussing some of the protection-related history of World-Wide-Web servers and clients, some of their betterknown vulnerabilities, and the need for a more secure server environment. We then discuss the protection goals we believe to be of import to a World-Wide-Web server, outline some of the principles we believe to be important to attaining such a server, and analyze the design of a server that we believe to be secure relative to my stated goals. Finally, we discuss some of the experience we have had with this server, the development of a secure gopher server using nearly the same code, and future work. Copyright  相似文献   

11.
Understanding how software systems evolve is useful from different perspectives: reverse engineering, empirical studies etc.. For an effective understanding we need an explicit meta-model. We introduce Hismo, a meta-model which is centered around the notion of history and we show how we can obtain it from a snapshot meta-model. Based on our experience in developing the Hismo reverse engineering system, we show how we can transform a snapshot meta-model in a history meta-model.  相似文献   

12.
In this paper, we present a system that visualizes the expressive quality of a music performance using a virtual head. We provide a mapping through several parameter spaces: on the input side, we have elaborated a mapping between values of acoustic cues and emotion as well as expressivity parameters; on the output side, we propose a mapping between these parameters and the behaviors of the virtual head. This mapping ensures a coherency between the acoustic source and the animation of the virtual head. After presenting some background information on behavior expressivity of humans, we introduce our model of expressivity. We explain how we have elaborated the mapping between the acoustic and the behavior cues. Then, we describe the implementation of a working system that controls the behavior of a human-like head that varies depending on the emotional and acoustic characteristics of the musical execution. Finally, we present the tests we conducted to validate our mapping between the emotive content of the music performance and the expressivity parameters.  相似文献   

13.
论文主要考虑多用户的MIMO-OFDM问题,以使得各个用户更公平有效地分配网络资源。文章首先给出MIMO-OFDM模型,然后引入反映用户满意程度的效益函数,并给出在MIMO-OFDM模型下的效益函数具体形式。其次,进行资源分配,重点考虑OFDM的各个子载波该分配给哪个用户,以及总功率该如何分配给各个子载波,从而实现系统的最优化。最后,文章给出了仿真结果,并着重对仿真结果进行了详细的性能分析。  相似文献   

14.
In this paper we describe an experience in designing a groupware application distributed over the WWW to solve a conference management problem. The system we design coordinates the activities of several people engaged in reviewing and selecting papers submitted for a scientific conference. We discuss why such an application is interesting and describe how we designed it. The architecture we suggest implements what we call an active Web, because it includes entities which we are able to use and provide services offered through WWW infrastructures. Users, agents, and active documents can interoperate using a set of basic services for communication and synchronization. The active Web infrastructure we describe here is based on coordination technology integrated with Java.  相似文献   

15.
劳志强  潘云鹤 《计算机工程》1997,23(5):60-63,70
该文首先对影象计算中变形算法的研究作了一个简要的概述,然后结合我们目前所进行的智能动画的研究工作,提出了一个在影象空间中基于全局优化的影象变形算法。在文中第二节较主详细地介绍了该算法中所用到的散乱点播值算法,最后给出了该算法的详细描述。  相似文献   

16.
In this paper, we investigate how the raise of big data and cognitive computing systems is going to redesign the labor market, also impacting on the learning processes. In this respect, we make reference to higher education and we depict a model of a smart university, which relies on the concepts that are at the basis of the novel smart-cities’ development trends. Thus, we regard education as a process so that we can find specific issues to solve to overcome existing criticisms, and provide some suggestions on how to enhance universities’ performances. We highlight inputs, outputs, and dependencies in a block diagram, and we propose a solution built on a new paradigm called smarter-university, in which knowledge grows rapidly, is easy to share, and is regarded as a common heritage of both teachers and students. Among the others, a paramount consequence is that there is a growing demand for competences and skills that recall the so called T-shape model and we observe that this is pushing the education system to include a blend of disciplines in the curriculums of their courses. In this overview, among the wide variety of recent innovations, we focus our attention on cognitive computing systems and on the exploitation of big data, that we expect to further accelerate the refurbishment process of the key components of the knowledge society and universities as well.  相似文献   

17.
STEPHAN DIEHL 《Software》1997,27(1):49-62
In this article we present Typed Feature Structures as an extension of Prolog, and show how to come up with a compilation scheme and an abstract machine using a design methodology based on partial evaluation. First we define the transformations used by our partial evaluator. Then we present the design methodology which we will use later. Next, we clarify the notion of Typed Feature Structures that underlies our work, and formally define the unification of such structures. Based on this definition, we develop a unification procedure with explicit heap representation. By partially evaluating this procedure with respect to some example programs, we show how to come up with the machine instructions and translation schemes. Finally, we briefly address coreferences, cyclic structures and the unification of types. © 1997 by John Wiley & Sons, Ltd.  相似文献   

18.
In this paper we introduce a new dynamical system of a pushdown automaton, called automaton with a stack (AS). We prove that every AS has a periodic configuration by construction of it. Next, we define a special case of an AS, called AS with finite memory and we prove that the AS has a finite memory if and only if it is positively expansive. Furthermore, we prove that every AS with finite memory has shadowing property. Having these two properties, we set a finite-to-one map between an AS with finite memory and some vertex subshift, which gives us a semi-conjugacy between these two systems. Additionally, we define an algorithm to decide if a given graph G describes some AS with finite memory and to calculate maximal depth of a stack.  相似文献   

19.
In this paper we recall general methodologies we developed for observation and identification in non-linear systems theory, and we show how they can be applied to real practical problems.

In a previous paper, we introduced a filter which is intermediate between the extended Kalman filter in its standard version and its high-gain version, and we applied it to certain observation problems. But we were missing some important cases. Here, we show how to treat these cases.

We also apply the same technique in the context of our identifiability theory.

As non-academic illustrations, we treat a problem of observation and a problem of identification, for a fluid catalytic cracker (FCC). This FCC unit is one of the most crucial from an economic point of view for the petroleum industry.  相似文献   

20.
《Advanced Robotics》2013,27(3-4):371-394
In this paper, we propose an improved design methodology to meet the changing demands of an existing automated container transportation system in which automated guided vehicles (AGVs) are used. This system is called an AGV transportation system. To achieve an improved design, it is essential to detect and correct any occurring bottlenecks. For this purpose, we exhaustively enumerate design proposals by constructing a logic tree. As a case study to verify the proposed methodology, we apply the methodology to an existing AGV transportation system. From the enumerated design proposals, we suggest design policies by considering the actual constraints of the transportation system. Finally, we redesign the transportation system as rapidly as possible. On the other hand, we keep system balancing into account; then, we derive a suitable demand and input number of AGVs under given specifications for a transportation system.  相似文献   

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