Query Refinement is an essential information retrieval tool that interactively recommends new terms related to a particular query. This paper introduces concept recall, an experimental measure of an algorithm's ab...
ISBN:
(纸本)0897918363
Query Refinement is an essential information retrieval tool that interactively recommends new terms related to a particular query. This paper introduces concept recall, an experimental measure of an algorithm's ability to suggest terms humans have judged to be semantically related to an information need. This study uses precision improvement experiments to measure the ability of an algorithm to produce single term query modifications that predict a user's information need as partially encoded by the query. An oracle algorithm produces ideal query modifications, providing a meaningful context for interpreting precision improvement results. This study also introduces RMAP, a fast and practical query refinement algorithm that refines multiple term queries by dynamically combining precomputed suggestions for single term queries. RMAP achieves accuracy comparable to a much slower algorithm, although both RMAP and the slower algorithm lag behind the best possible term suggestions offered by the oracle. We believe RMAP is fast enough to be integrated into present day Internet search engines: RMAP computes 100 term suggestions for a 160,000 document collection in 15 ms on a low-end PC.
作者：
Chris McDonaldKamran KazemiProgramming
Languages and Systems Group Department of Computer Science The University of Western Australia Crawley Western Australia 6907
The parallel programming community has long recognized the need for a simple programming environment offering interprocess communication between heterogeneous systems. As the Parallel Virtual Machine environment, PVM,...
ISBN:
(纸本)9780897918893
The parallel programming community has long recognized the need for a simple programming environment offering interprocess communication between heterogeneous systems. As the Parallel Virtual Machine environment, PVM, has emerged to meet this goal, an increasing number of educational institutions are choosing PVM to support their teaching of parallel and distributed computing using networks of workstations. However, it is often the nature of PVM's design and implementation that can severely limit its success in a teaching environment. This paper first motivates and then describes improvements to the PVM environment which increase both robustness and efficiency in an educational setting.
Fail-safety is a system attribute which ensures that a program either completes its execution satisfying its post-conditions in the normal manner or signals its failure to do so to its operating environment. Such an a...
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Fail-safety is a system attribute which ensures that a program either completes its execution satisfying its post-conditions in the normal manner or signals its failure to do so to its operating environment. Such an attribute is desirable of any system as it ensures the correctness of results which are produced. A very few modern sequential programming languages offer program fail-safety through the judicious use of a well designed exception handling mechanism. In this paper the exception handling techniques used in those sequential systems are developed to provide the guidelines for fail-safe concurrent system design. (C) 1997 Elsevier Science Ltd.
作者：
Chris McDonaldProgramming
Languages and Systems Group Department of Computer Science The University of Western Australia Crawley Western Australia
One of the greatest benefits provided by computer networks, in particular local area networks, is the ability to access files served by other computers in a network. Whereas file system concepts are first introduced i...
ISBN:
(纸本)9780897917575
One of the greatest benefits provided by computer networks, in particular local area networks, is the ability to access files served by other computers in a network. Whereas file system concepts are first introduced in Operating systems units, many file system concepts need to be readdressed and generalized in later Computer Networks units. Moreover, as students become increasingly familiar with internetworking and programs such as ftp, many of the strong links between the Operating systems and Computer Networks units may be reinforced. This paper discusses the successes experienced with two strongly related projects offered in our third year Computer Networks unit. Each project requires students to support a minimal distributed file system by implementing user-level libraries which redefine a handful of operating system system calls supporting remote file access.
Lack of machine intelligibility in human/computer interactions can be traced to present approaches in software design. From the duality principle, software involved in human/computer software interaction contains two ...
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Lack of machine intelligibility in human/computer interactions can be traced to present approaches in software design. From the duality principle, software involved in human/computer software interaction contains two distinct layers, a declarative knowledge-level layer and a lower-level functional or procedural-knowledge layer. The former supports simple deductive and inductive inferences and can be used to facilitate human-comprehensible communication between programs, while the latter is composed of normal procedurally encoded computer programs. The duality principle in software design is necessary in dealing with the demands of wide-scale computer usage in the information age and an urgent goal for computer science research.
This paper details the use of a circuit-based EM modelling technique combined with a harmonic balance simulator used to model the radiation from the microstrip bodies comprising an active antenna circuit. The modellin...
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This paper details the use of a circuit-based EM modelling technique combined with a harmonic balance simulator used to model the radiation from the microstrip bodies comprising an active antenna circuit. The modelling approach adopted for the planar bodies in the circuit will be shown to allow the use of concurrent algorithms in order to reduce overall computational time.
Since the mid-1970s, and with the development of each new programming paradigm there has been an increasing interest in exceptions and the benefits of exception handling. With the move towards programming for ever mor...
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Since the mid-1970s, and with the development of each new programming paradigm there has been an increasing interest in exceptions and the benefits of exception handling. With the move towards programming for ever more complex architectures, understanding basic facilities such as exception handling as an aid to improving program reliability, robustness and comprehensibility has become much more important. Interest has sparked the production of many papers both theoretical and practical, each giving a view of exceptions and exception handling from a different standpoint. In an effort to provide a means of classifying exception handling models which may be encountered, a taxonomy is presented in this paper. As the taxonomy is developed some of the concepts of exception handling are introduced and discussed. The taxonomy is applied to a number of exception handling models in some contemporary programming languages and some observations and conclusions offered.
A formal framework for a calculus of real-time systems is presented. Specifications and program statements are combined into a single language called TAM (the Temporal Agent Model), that allows the user to express bot...
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A major limitation of the boundary element method (BEM) for the solution of electrical potential problems is the long computational time required. However, a large portion of the calculations involved can be viewed as...
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A major limitation of the boundary element method (BEM) for the solution of electrical potential problems is the long computational time required. However, a large portion of the calculations involved can be viewed as being parallel in nature and can therefore be computed concurrently. This paper makes an effort to increase the efficiency of the BEM process using transputer-based multiprocessor computing techniques. The algorithms developed may equally well be applied to any multiprocessor system. The application selected to demonstrate the technique is the solution of an electrostatic problem governed by a two-dimensional Laplace equation. A parallel algorithm for problem setup and field extraction using BEM is designed and implemented on a transputer array. Special attention is directed to the utilization of the parallel processors to achieve maximum efficiency. The analysis in this work concentrates on the communication strategies for passing data between processors as well as a consideration of the workload attributed to each processor. The parallel algorithms were implemented using 3L Parallel Fortran;however, the choice of topology for the overall BEM implementation was limited by the fact that certain parts of the algorithm could only utilize a pipeline configuration of processors. Comprehensive results for the parallel BEM algorithm are given and they are encouraging, indicating that parallel processing has much to offer when applied to the boundary element method.
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