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Handling Sparse Data by Successive Abstraction  [PDF]
Christer Samuelsson
Computer Science , 1996,
Abstract: A general, practical method for handling sparse data that avoids held-out data and iterative reestimation is derived from first principles. It has been tested on a part-of-speech tagging task and outperformed (deleted) interpolation with context-independent weights, even when the latter used a globally optimal parameter setting determined a posteriori.
Design of WWW-Z39.50 Gateway
WWW-Z39.50网关的设计与实现*

Hu Jie Chen Zhigang Sun Bianhua,
胡杰
,陈志刚,孙辨华

现代图书情报技术 , 2000,
Abstract: Z39.50 (ISO 23950), is the international standard and protocol for information retrieval. It has been used in the area of information because of the powerful function, interactive operation and contents in abundance.WWW-Z39.50 gateway has inherited and developed the structure of traditional Client/Server. By combining the Z39.50 with WWW, and giving users simple, uniform, friendly user interface, this system colonized the usage of Z39.50 greatly. WWW-Z39.50 gateway is a key technology of “New-generation Library Information System ”. In this article we introduce the structure, function and technology of WWW -Z39. 50 gateway, and compares it with the C/S. In the end, we talk about the new trend of Z39. 50.
Secure Abstraction with Code Capabilities  [PDF]
Robbert van Renesse,H?vard Johansen,Nihar Naigaonkar,Dag Johansen
Computer Science , 2012,
Abstract: We propose embedding executable code fragments in cryptographically protected capabilities to enable flexible discretionary access control in cloud-like computing infrastructures. We are developing this as part of a sports analytics application that runs on a federation of public and enterprise clouds. The capability mechanism is implemented completely in user space. Using a novel combination of X.509 certificates and Javscript code, the capabilities support restricted delegation, confinement, revocation, and rights amplification for secure abstraction.
Nominal Abstraction  [PDF]
Andrew Gacek,Dale Miller,Gopalan Nadathur
Computer Science , 2009,
Abstract: Recursive relational specifications are commonly used to describe the computational structure of formal systems. Recent research in proof theory has identified two features that facilitate direct, logic-based reasoning about such descriptions: the interpretation of atomic judgments through recursive definitions and an encoding of binding constructs via generic judgments. However, logics encompassing these two features do not currently allow for the definition of relations that embody dynamic aspects related to binding, a capability needed in many reasoning tasks. We propose a new relation between terms called nominal abstraction as a means for overcoming this deficiency. We incorporate nominal abstraction into a rich logic also including definitions, generic quantification, induction, and co-induction that we then prove to be consistent. We present examples to show that this logic can provide elegant treatments of binding contexts that appear in many proofs, such as those establishing properties of typing calculi and of arbitrarily cascading substitutions that play a role in reducibility arguments.
BATS: a Bayesian user-friendly software for Analyzing Time Series microarray experiments
Claudia Angelini, Luisa Cutillo, Daniela De Canditiis, Margherita Mutarelli, Marianna Pensky
BMC Bioinformatics , 2008, DOI: 10.1186/1471-2105-9-415
Abstract: The software package BATS (Bayesian Analysis of Time Series) presented here implements the methodology described above. It allows an user to automatically identify and rank differentially expressed genes and to estimate their expression profiles when at least 5–6 time points are available. The package has a user-friendly interface. BATS successfully manages various technical difficulties which arise in time-course microarray experiments, such as a small number of observations, non-uniform sampling intervals and replicated or missing data.BATS is a free user-friendly software for the analysis of both simulated and real microarray time course experiments. The software, the user manual and a brief illustrative example are freely available online at the BATS website: http://www.na.iac.cnr.it/bats webciteGene expression levels in biological systems can be influenced by different stimuli, e.g. pharmacological or medical treatments. The response is a dynamic process, usually different for different genes. One of the goals of modern molecular biology is the high-throughput identification of genes associated with a particular treatment or a biological process of interest. The recently developed microarray technology allows one to simultaneously monitor the expression levels of thousands of genes, thus providing a "molecular picture" of a biological system under study and a potential of describing evolution of gene expressions in time. However, this potential has not yet been fully exploited since there is still a shortage of statistical methods which take into account the temporal relationship between the samples in microarray analysis. In fact, most of the existing software packages essentially apply techniques designed for static data to time-course microarray data. For example, the SAM software package (see [1]) was recently adapted to handle time course data by regarding the different time points as different groups. The ANOVA approach by [2] was applied to time course e
Optimization of WWW Navigation Path Based on User Access Patterns
基于用户访问模式的WWW浏览路径优化

YANG Xiao hua,ZHOU Long xiang,
阳小华
,周龙镶

软件学报 , 2001,
Abstract: In this paper,the authors analyze the activities of WWW users and present a series of concepts about optimization of WWW navigating path. Furthermore,an algorithm of optimization of WWW navigating path is given,that is based on user access pattern and other related works are compared with.
MeGARA: Menu-based Game Abstraction and Abstraction Refinement of Markov Automata  [PDF]
Bettina Braitling,Luis María Ferrer Fioriti,Hassan Hatefi,Ralf Wimmer,Bernd Becker,Holger Hermanns
Computer Science , 2014, DOI: 10.4204/EPTCS.154.4
Abstract: Markov automata combine continuous time, probabilistic transitions, and nondeterminism in a single model. They represent an important and powerful way to model a wide range of complex real-life systems. However, such models tend to be large and difficult to handle, making abstraction and abstraction refinement necessary. In this paper we present an abstraction and abstraction refinement technique for Markov automata, based on the game-based and menu-based abstraction of probabilistic automata. First experiments show that a significant reduction in size is possible using abstraction.
On a User Friendly Code on Visualizing Higher Dimensional Data Using Parallel Coordinates
Abhishek Kumar Maurya,Soubhik Chakraborty
Research Journal of Applied Sciences , 2012,
Abstract: The present note is gives a user friendly code on parallel coordinates which can be used to visualize higher dimensional data.
Completeness of Lyapunov Abstraction  [PDF]
Rafael Wisniewski,Christoffer Sloth
Computer Science , 2013, DOI: 10.4204/EPTCS.124.5
Abstract: In this work, we continue our study on discrete abstractions of dynamical systems. To this end, we use a family of partitioning functions to generate an abstraction. The intersection of sub-level sets of the partitioning functions defines cells, which are regarded as discrete objects. The union of cells makes up the state space of the dynamical systems. Our construction gives rise to a combinatorial object - a timed automaton. We examine sound and complete abstractions. An abstraction is said to be sound when the flow of the time automata covers the flow lines of the dynamical systems. If the dynamics of the dynamical system and the time automaton are equivalent, the abstraction is complete. The commonly accepted paradigm for partitioning functions is that they ought to be transversal to the studied vector field. We show that there is no complete partitioning with transversal functions, even for particular dynamical systems whose critical sets are isolated critical points. Therefore, we allow the directional derivative along the vector field to be non-positive in this work. This considerably complicates the abstraction technique. For understanding dynamical systems, it is vital to study stable and unstable manifolds and their intersections. These objects appear naturally in this work. Indeed, we show that for an abstraction to be complete, the set of critical points of an abstraction function shall contain either the stable or unstable manifold of the dynamical system.
Expressiveness and Completeness in Abstraction
Maciej Gazda,Tim A.C. Willemse
Electronic Proceedings in Theoretical Computer Science , 2012, DOI: 10.4204/eptcs.89.5
Abstract: We study two notions of expressiveness, which have appeared in abstraction theory for model checking, and find them incomparable in general. In particular, we show that according to the most widely used notion, the class of Kripke Modal Transition Systems is strictly less expressive than the class of Generalised Kripke Modal Transition Systems (a generalised variant of Kripke Modal Transition Systems equipped with hypertransitions). Furthermore, we investigate the ability of an abstraction framework to prove a formula with a finite abstract model, a property known as completeness. We address the issue of completeness from a general perspective: the way it depends on certain abstraction parameters, as well as its relationship with expressiveness.
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