bluuebunny/crossref_metadata_2025 huggingface dataset:
Building interfaces as personal agents
Authors: Cesta Amedeo , D'Aloisi Daniel
Published: January 2007

This paper concerns the development of interfaces which perform tasks on behalf of the user. Recently the concept of task delegation has gained consideration due to the increasing number of assignments that are quite repetitive and tedious, like dealing with electronic messages, managing personal agendas, retrieving data and information in remote and distributed repositories. These tasks are generally connected to the development of computer networks. The design of such interfaces presents a high degree of complexity, since the relationship with the user and his needs is very critical: in most cases the user wants to control the jobs to be mechanized but in the same time he wants to be free from wasting his time in performing repetitive patterns of actions. In this paper the main problems concerning the design of active and cooperative interfaces are investigated. Then a solution is proposed based on the approaches of software agents and distributed architectures. Starting point of the project is to integrate and make accessible different tools and applications regularly utilized by a user: all these elements concur in building a flexible and scalable environment that the user can access through intelligent agents that work as interfaces.
The management of human errors in user-centered design
Authors: Rizzo A. , Parlangeli O. , Marchigiani E. , Bagnara S.
Published: January 2007

User-Centered Design puts the users at the center of the design activity by involving them from the very beginning in the process and by iteratively testing and re-designing the product. In every testing and evaluation phase human error analysis plays an important role. Although it is not possible to design systems in which people do not make errors, much can be done to minimize the incidence of error, to maximize error detection, and to make easier error recovery. However, the qualitative analysis on human error has not received the attention that it deserves. In the paper the main features of the user-centered approach are sketched and a set of guidelines for handling human error is presented. An example drawn from our design experience is reported for each guideline.
A report on OpenMath
Authors: Abbott John , Díaz Angel , Sutor Robert S.
Published: January 2007

The proliferation of general purpose mathematical software and specialized mathematical libraries has provided a wealth of computing resources for students, scientists, and engineers. The challenge remains to harness the power of these independent software tools within a single framework. OpenMath will provide formats and a protocol for the exchange of mathematical expressions and objects, thus enabling a unification from a user's point of view. This work will also allow the inclusion of mathematical objects in a universal format within databases and electronically published scientific and technical documents.This report will detail the steps taken to date by the OpenMath Consortium to achieve the aforementioned goals. In particular, §2 provides an overview of OpenMath. Emphasis is placed on OpenMath's design goals, initial target applications, and Consortium structure. In §3, an exposition of the levels of the OpenMath model which maps mathematical concepts to their respective concrete representations is provided. Some issues that arise when a mathematical object is transcribed between its visual form and internal representation are presented in §4. Finally, §5 and §6 communicate the current state of the OpenMath prototyping efforts and concomitantly detail the future directions of the OpenMath consortium.
An object-oriented model for a multimedia patient folder management system
Authors: Ferri Fernando , Pisanelli Domenico M. , Ricci Fabrizio L.
Published: January 2007

The management of information related to clinical activities is a complex task. In fact, patient related information reported in patient folders comes from heterogeneous sources and may be rendered by means of different modalities. Data can originate from direct observations made by physicians like in the case of objective examination. In other cases physiologic phenomena are captured by means of the involved electrical activity (like in the case of heart or brain activity), whereas anatomical structure details are obtained by means of radiologic techniques. In this paper we propose an object-oriented model of a multimedia patient folder. This model has an adequate flexibility for adapting the most different clinical environment. It allows the physician to structure the information needed for his/her patient folder without employing a programming language. Finally we show some features of the CADMIO system, a tool for designing patient folder management systems, based on this model.
Experiments with digital video playback
Authors: Gerber Richard , Gharai Ladan
Published: January 2007

In this paper we describe our experiments on digital video applications, concentrating on the static and dynamic tradeoffs involved in video playback. Our results were extracted from a controlled series of 272 tests, which we ran in three stages.In the first stage of 120 tests, we used a simple player-monitor tool to evaluate the effects of various static parameters:
compression type, frame size, digitized rate, spatial quality
and
keyframe distribution.
The tests were carried out on two Apple Macintosh platforms: at the lower end a Quadra 950, and at the higher end, a Power PC 7100/80. Our quantitative metrics included average playback rate, as well as the rate's variance over one-second intervals.The first set of experiments unveiled several anomalous latencies. To track them down we ran an additional 120 tests, from which we concluded that the video and IO operations were insufficiently tuned to each other.In the next step we attempted to correct this problem, by implementing our own video playback software and accompanying device-level handlers. Our emphasis was on achieving a controlled, deterministic coordination between the various system components. An additional set of 32 experiments were carried out on our platforms, which showed frame-rate increases of up to 325%, with associated reductions in rate variance.
Conservative parallel simulation of ATM networks
Authors: Cleary John G. , Tsai Jya-Jang
Published: January 2007

A new Conservative algorithm for both parallel and sequential simulation of networks is described. The technique is motivated by the construction of a high performance simulator for ATM networks. It permits very fast execution of models of ATM systems, both sequentially and in parallel. A simple analysis of the performance of the system is made. Initial performance results from parallel and sequential implementations are presented and compared with comparable results from an optimistic TimeWarp based simulator. It is shown that the conservative simulator performs well when the "density" of messages in the simulated system is high, a condition which is likely to hold in many interesting ATM scenarios.
Automatic incremental state saving
Authors: West Darrin , Panesar Kiran
Published: January 2007

We present an Incremental State Saving technique for which the state saving calls are inserted automatically by directly editing the application executable. This method has the advantage of being easy to use since it is fully automatic, and has good performance since it adds overhead only where state is being modified. Since the editing happens on executable code, the method is independent of the compiler, and allows third party libraries to be used. None of the previous incremental state saving methods have both of these features. We find that it is beneficial to use Automatic Incremental State Saving if less than 15% of the state is modified in each event as compared to copy state saving. This technique allows us to efficiently parallelize existing simulations, and makes Time Warp more accessible to non-Time Warp experts.
Design of high level modelling / high performance simulation environments
Authors: Zeigler Bernard P. , Kim Doohwan
Published: January 2007

Advances in massively parallel platforms are increasing the prospects for high performance discrete event simulation. Still the difficulty in parallel programming persists and there is increasing demand for high level support for building discrete event models to execute on such platforms. We present a parallel DEVS-based (Discrete Event System Specification) simulation environment that can execute on distributed memory multicomputer systems with benchmarking results of a class of high resolution, large scale ecosystem models. Underlying the environment is a parallel container class library for hiding the details of message passing technology while providing high level abstractions for hierarchical, modular DEVS models. The C++ implementation working on the Thinking Machines CM-5 demonstrates that the desire for high level modeling support need not be irreconcilable with sustained high performance.
Queueing models and stability of message flows in distributed simulators of open queueing networks
Authors: Gupta Manish , Kumar Anurag , Shorey Rajeev
Published: January 2007

In this paper we study message flow processes in distributed simulators of open queueing networks. We develop and study queueing models for distributed simulators with maximum lookahead sequencing. We characterize the "external'' arrival process, and the message feedback process in the simulator of a simple queueing network with feedback. We show that a certain "natural'' modelling construct for the arrival process is exactly correct, whereas an ``obvious'' model for the feedback process is wrong; we then show how to develop the correct model. Our analysis throws light on the stability of distributed simulators of queueing networks with feedback. We show how the stability of such simulators depends on the parameters of the queueing network.
Discrete-event simulation and the event horizon part 2
Authors: Steinman Jeffrey S.
Published: January 2007

The event horizon is a very important concept that applies to both parallel and sequential discrete-event simulations. By exploiting the event horizon, parallel simulations can processes events optimistically in a risk-free manner (i.e., without requiring antimessages) using adaptable "breathing" time cycles with variable time widths. Additionally, exploiting the event horizon can significantly reduce the overhead of event list management that is common to virtually all discrete-event simulations. This paper is a continuation of work previously reported at PADS94. In that report, a complete mathematical formulation of the event horizon was derived under equilibrium conditions using the hold model. Various forms of the beta density function were consequently used to verify the predicted results of the analytic model. This second report describes how the concept of the event horizon can also be applied to event list management. By exploiting the event horizon, the performance of several priority queue data structures are improved including: linked lists, various binary trees, and heaps. A somewhat detailed description of these modified data structures along with other relevant background information is provided for completeness. Performance results for each of these priority queue data structure is provided.
A performance evaluation methodology for parallel simulation protocols
Authors: Jha Vikas , Bagrodia Rajive
Published: January 2007

Most experimental studies of the performance of parallel simulation protocols use speedup or number of events processed per unit time as the performance metric. Although helpful in evaluating the usefulness of parallel simulation for a given simulation model, these metrics tell us little about the efficiency of the simulation protocol used. In this paper, we describe an Ideal Simulation Protocol (ISP), based on the concept of critical path, which experimentally computes the best possible execution time for a simulation model on a given parallel architecture. Since ISP computes the bound by actually executing the model on the given parallel architecture, it is much more realistic than that computed by a uniprocessor critical path analysis. The paper illustrates, using parameterized synthetic benchmarks, how an ISP-based performance evaluation can lead to much better insights into the performance of parallel simulation protocols than what would be gained from speedup graphs alone.
Book review: CASE-BASED REASONING by Janet Kolodner (Morgan Kaufmann Publishers, 1993)
Authors: Zeleznikow John
Published: January 2007

As someone who has been performing research in case based reasoning for the past five years, I had eagerly awaited the arrival of Janet Kolodner's monumental treatise on case based reasoning. While I found the book invaluable, the depth in which topics are covered, and the number of issues raised in Kolodner's book, make it unsuitable for browsing. Dedicated graduate students and researchers will greatly benefit from studying Kolodner's book; however I would hesitate before recommending it to novices. The latter group would be better served by reading one of the numerous review articles on case based reasoning that have recently appeared (see below), or by reading the shorter introduction in [7].
Context-dependent computational components
Authors: Dean Thomas L.
Published: January 2007

Many applications can be described in terms of a control system embedded in a dynamic environment. The computational components that comprise such an embedded system often must be responsive to the context in which they are executed. In order to be responsive, they must specify how their performance affects and is affected by context. This paper considers anytime algorithms as a particular sort of context-dependent computational component. Traditional anytime algorithms are passive components that provide performance specifications to external processes and receive allocations of computational resources in return. We also consider context-dependent components that are interactive, probing the environment to establish their value in a given context and competing with other components for computational resources.
Using Microsoft Access to store function definitions
Authors: Bowman Dick
Published: January 2007

T
HIS PAPER SUMMARISES
some preliminary experimentation using Microsoft Access as a vehicle for storing APL function definitions separately from the workspace. The work appears to offer some advantages in terms of improved code portability between interpreters.
Will parallel simulation come to an end?
Authors: Lin Jason Yi-Bing
Published: January 2007

In 1987, I worked on the performance issues of the multi-processor caches under the supervision of Professor Jean-Loup Baer. We used the trace-driven simulation approach and found that the process might be too time consuming. Then we investigated the possibility of utilizing multiple processors to speed up the simulation procedure. At this point, my thesis advisor Professor Edward Lazowska joined in the project. By exploiting the communication patterns of the cache protocols under study, we observed the number of synchronization operations among the processors (that execute the cache simulation) can be significantly reduced. Thus, good speedup could be achieved. We published this exciting results in the Proceedings of the SCS Multi-Conferences on Distributed Simulation. After we finished this project, I felt that "It is too expensive to develop a parallel simulation program just for one application. It is desirable to develop a general simulation system." Jean-Loup showed me two papers:1. Chandy, K. M., and Misra, J., "Distributed Simulation: A Case Study in Design and Verification of Distributed Programs." IEEE Trans. on Software Engineering, SE-5, 1979.2. Jefferson, D., "Virtual Time." ACM Transactions on Programming Languages and Systems, July, 1985.
Enforcement strategies for computer use violations at a public university
Authors: Craig Jacqueline
Published: January 2007

Crafting appropriate use policies (AUP), is only the first step in addressing issues of inappropriate use of electronic resources on our college and university campuses. Many AUP's are intentionally general in order to cover as many contingencies as possible. Older AUP's may not have addressed many of the violations that have become more common with the advent of World Wide Web servers. The proliferation of computing activities and expanded body of users unfortunately has spawned an equally growing number of questionable activities. When confronted with these perceived inappropriate uses, computer resource managers must organize rational enforcement responses which assure due process and the protection of constitutional rights and privileges for all individuals.
John Reid reports: X3J3 meeting, February 1987
Authors: Reid John
Published: January 2007

A letter ballot of all X3J3 members was conducted prior to this meeting, asking the question "Do you approve the draft Fortran Revision...enclosed with this ballot for submission to X3 for further processing as an American National Standard?" The result was Yes: 9; Yes with comments, 20; No: 7. Since less than 1/3 voted "no", the ballot passed. Short summaries of the reasons given for each no vote appear in Section 2. It looks of 2 or 3 of these may change to yes votes once all the comments have been processed, but the rest are asking for drastic changes that are quite unacceptable to a majority of the Committee.
Finding heuristics for flowshop scheduling
Authors: Bernstein M
Published: January 2007

Different flow shops are characterized by different-often wildly different--preferences and constraints. While simple heuristics often permit efficient construction of excellent schedules, the discovery of such heuristics generally depends on deep managerial insight or on trial and error. Given a description of a flowshop, the SH program proposes and tries to solve scheduling problems in order to identify heuristics which are especially valuable to the problem at hand.
Book review: Universal Subgoaling and Chunking: The automatic generation and learning of goal hierarchies by John Laird, Paul Rosenbloom, and Alan Newell
Authors: Murphy Art , Jagannathan V. , Bradshaw J.
Published: January 2007

This book is two Ph.D theses bound together in one volume. The first thesis is by John Laird and is on "Universal Subgoaling" and the second thesis is on "The chunking of goal hierarchies" by Paul Rosenbloom. Alan Newell, their Ph.D advisor has an interesting preface, explaining how the respective thesis topics came into being. The first part (thesis) of the book is on developing a generalized problem solving architecture. The second part (thesis) is to develop a generalized learning system. The concluding section ties the loose ends together.
Audio enhanced 3D interfaces for visually impaired users
Authors: Mereu Stephen W. , Kazman Rick
Published: January 2007

Three dimensional computer applications such as CAD packages are often difficult to use because of inadequate depth feedback to the user. It has, however, been shown that audio feedback can help improve a user's sense of depth perception. This paper describes an experiment which evaluates the use of three different audio environments in a 3D task undertaken by visually impaired users. The three audio environments map tonal, musical, and orchestral sounds to an (x, y, z) position in a 3D environment. In each environment the user's task is to locate a target in three dimensions as accurately and quickly as possible. This experiment has three important results: that audio feedback improves performance in 3D applications for all users; that visually impaired users can use 3D applications with the accuracy of sighted users; and that visually impaired users can attain greater target accuracy than sighted users in a sound-only environment
Monitoring the efficiency of a reuse program
Authors: Benedicenti L. , Succi G. , Valerio A. , Vernazza T.
Published: January 2007

Introducing software reuse at a corporate wide level represents one of the most promising means of addressing rising costs plaguing the software industry. A series of mechanisms are needed for shortening development cycles and providing reliable software of high quality which will be more maintainable and flexible for future extensions.This paper presents an overview of a reuse program that is intended to institutionalise a software reuse process that incorporates reuse-specific activities all along an object oriented software development process, drawing heavily on a reusable software artifact library system which has been designed to support the classification, management and search for artifacts to be employed in reuse efforts.Due to the increasing competition and rapid technological innovations that mark nowadays the software applications' field, this sector has undergone radical changes, forcing operators to cope with a growing demand of new applications and services, in terms of quality, variety, reliability, and, last but not least, low prices.In this situation the traditional custom software development methodologies show all its inadequateness and ineffectiveness: to become really competitive in developing new applications, able to survive in a global market, an organisation needs to adopt leading edge technologies inside a defined, well planned and specific software development process.Moreover, traditional software development methodologies do not allow an efficient maintenance of the products, while any modification or extension of these products often results in a full redevelopment of them.A new iterative development philosophy based on software reuse and using the emerging object oriented technologies seems to be the right trade-off among the opposed factors characterising a successful telecommunication product or service: high-quality, low-cost, reduced time-to-market, flexibility and maintainability, just to tell some. In this view, a systematic reuse program to support and to integrate the software development activities, incorporating a reuse library to support the classification and management of the heterogeneous reusable components, is a particularly interesting and promising methodology.
MPCR
Authors: Bachmann Olaf
Published: January 2007

MPCR
is a stand-alone, flexible, and efficient implementation of the Chains of Recurrences (CR) method. It can be used interactively, as a network-based server, or as a library. Using the CR method,
MPCR
evaluates closed-form expressions over regular grids with great efficiency --- often hundreds of times faster than comparable programs.
MPCR
also features an MP (Multi Protocol) interface for data exchange, conditional CR simplification, use of intermediate evaluation arrays and generation of C source code. Evaluation timings are given and compared with other programs, and the algorithms which result in the high efficiency of
MPCR
are discussed.
The cookie cutter algorithm for handling mixed hierarchy
Authors: Sullivan N G , Rosenberg J B
Published: January 2007

When doing symbolic design in a mixed hierarchy system, primitives that route between cells must be encapsulated in cells themselves to make the job of the compactor easier. To free the designer from that tedium, a transparent process between layout and compaction creates new cells and drops the primitives into them. The designer is thus freed from creating new routing cells every time the design changes, and compaction is more efficient since it can be truly hierarchical.
A CAUSAL MODEL OF HUMAN VS. COMPUTER INTERACTION PREFERENCE FOR NAIVE USERS
Authors: Coovert Michael D.
Published: January 2007

The literature has suggested several factors which should be related to if an individual prefers to interact with a computer or another person for any specific task. These factors include, among others, the amount of computer experience an individual has, various personality traits, attitudes toward computers or technology, the capabilities of the computer system, and perceived aspects of the task. To date, however, there have been no attempts to develop and test causal models to explain these various relationships. This study hypothesized the casual relations illustrated in Figure 1 for explaining if an individual will prefer to interact with a computer versus a person for an interview task.
Control of structure and evaluation
Authors: Benkard J. Philip
Published: January 2007

Scalar conformance controls the structure phase of expression evaluation. Program control of this phase is achieved through insertion and deletion of scalar levels of structure. The basic functions to do this are ENCLOSE and DISCLOSE with axis. Their application in some common cases is made easier with proposed extensions to BRACKET INDEX and INTERVAL. This approach provides the function of a RANK operator with greater flexibility while keeping data structure information with the data.

A number of simple expression transformations have proved useful experimentally. Two operators are defined which in their several invocations provide full and partial currying and commutation of left and right arguments; composition, power, and dual of functions; composition, conversion between dyadic and monadic function syntax.

The variations in the definitions of partitions have led to suggestions that more than one primitive operation may be needed. Extensions to EACH and ENCLOSE are proposed which provide a wide range of function while satisfying numerous identities. Since these two operations are each used in APL2 to create a level of structure, the extensions are appropriate.
Adaptive flow control in time warp
Authors: Panesar Kiran S. , Fujimoto Richard M.
Published: January 2007

It is well known that Time Warp may suffer from poor performance due to excessive rollbacks caused by overly optimistic execution. Here we present a simple flow control mechanism using only local information and GVT that limits the number of uncommitted messages generated by a processor, thus throttling overly optimistic TW execution. The flow control scheme is analogous to traditional networking flow control mechanisms. A ``window'' of messages defines the maximum number of uncommitted messages allowed to be scheduled by a process. Committing messages is analogous to acknowledgments in networking flow control. The initial size of the window is calculated using a simple analytical model that estimates the instantaneous number of messages that a process will eventually commit. This window is expanded so that the process may progress up to the next commit point (generally the next fossil collection), and to accommodate optimistic execution. The expansions to the window are based on monitoring TW performance statistics so the window size automatically adapts to changing program behaviors.The flow control technique presented here is simple and fully automatic. No global knowledge or synchronization (other than GVT) is required. We also develop an implementation of the flow control scheme for shared memory multiprocessors that uses dynamically sized pools of free message buffers. Experimental data indicates that the adaptive flow control scheme maintains high performance for "balanced workloads'', and achieves as much as a factor of 7 speedup over unthrottled TW for certain irregular workloads.
Stack-free process-oriented simulation
Authors: Booth C. J. M. , Bruce D. I.
Published: January 2007

The process interaction world view is widely used in the general simulation community for its expressive power, and is supported by most modern simulation languages. In parallel discrete event simulation, however, its use remains comparatively rare due to the perceived inefficiency (and difficulty) of parallel implementations.We present a new implementation strategy for parallel process-oriented simulation languages. This innovative, semantics-based approach directly addresses two common concerns of such languages. By concentrating on the intrinsic threads of control, we avoid the proliferation of simulation objects (and their associated costs) that might result from a naive translation. More fundamentally, the primary costs associated with process-oriented languages -- those of context switching between stacks and, in an optimistic setting, of saving the state of these stacks -- are entirely eliminated since our explicit use of continuations avoids the need for stacks in the first place. We similarly obtain cheap and natural thread preemption.
A fuzzy approach to faceted classification and retrieval of reusable software components
Authors: Baruchelli Francesco , Succi Giancarlo
Published: January 2007

Software reuse can be very useful in increasing the productivity and the quality level of a company, but appropriate classification and retrieval tools have to be provided in order to exploit its pros. The classic classification and retrieval methods based upon a controlled, fixed vocabulary are not very flexible and can be unsatisfactory in many cases, especially when the specification are not fully defined. An improvement in this sense can be obtained applying some simple fuzzy concepts to the well known faceted classification method. Such a method based upon the same structures used in the traditional faceted classification is described. The method allows the user to specify how much a keyword is representative of the searched components, giving the means to specify the undesired keywords, too, through a set of fuzzy attributes.
Out-of-core FFTs with parallel disks
Authors: Cormen Thomas H. , Nicol David M.
Published: January 2007

We examine approaches to computing the Fast Fourier Transform (FFT) when the data size exceeds the size of main memory. Analytical and experimental evidence shows that relying on native virtual memory with demand paging can yield extremely poor performance. We then present approaches based on minimizing I/O costs with the Parallel Disk Model (PDM). Each of these approaches explicitly plans and performs disk accesses so as to minimize their number.
Steve
Authors: Johnson W. Lewis , Rickel Jeff
Published: January 2007

Virtual reality can broaden the types of interaction between students and computer tutors. As in conventional simulation-based training, the computer can watch students practice tasks, responding to questions and offering advice. However, immersive virtual environments also allow the computer tutor to inhabit the virtual world with the student. Unlike previous, disembodied computer tutors, such a "pedagogical agent" can "physically" collaborate with students, enabling new types of interaction. To illustrate the possibilities, this paper describes Steve, a pedagogical agent for virtual environments that helps students learn procedural tasks. After providing an overview of Steve's capabilities, the paper focuses on the benefits and challenges of graphically representing Steve in the virtual environment.
Faster IP lookups using controlled prefix expansion
Authors: Srinivasan V. , Varghese George
Published: January 2007

Internet (IP) address lookup is a major bottleneck in high performance routers. IP address lookup is challenging because it requires
a longest matching prefix
lookup. It is compounded by increasing routing table sizes, increased traffic, higher speed links, and the migration to 128 bit IPv6 addresses. We describe how IP lookups can be made faster using a new technique called
controlled prefix expansion
. Controlled prefix expansion, together with optimization techniques based on dynamic programming, can be used to improve the speed of the best known IP lookup algorithms by at least a factor of two. When applied to trie search, our techniques provide a range of algorithms whose performance can be tuned. For example, with 1 MB of L2 cache, trie search of the MaeEast database with 38,000 prefixes can be done in a worst case search time of 181 nsec, a worst case insert/delete time of 2.5 msec, and an average insert/delete time of 4 usec. Our actual experiments used 512 KB L2 cache to obtain a worst-case search time of 226 nsec, a worst-case worst case insert/delete time of 2.5 msec and an average insert/delete time of 4 usec. We also describe how our techniques can be used to improve the speed of binary search on prefix lengths to provide a scalable solution for IPv6. Our approach to algorithm design is based on measurements using the VTune tool on a Pentium to obtain dynamic clock cycle counts.
The development of profiles for monkeys and children with attention deficit disorder: a neural network approach
Authors: Hashemi Ray R. , Terry Michael S. , Tyler Alexander A. , Slikker William , Paule Merle G.
Published: January 2007

As a part of an Operant Test Battery (OTB), a set of five behavioral tasks was given to a group of children at the Arkansas Children's Hospital (ACH) and a group of rhesus monkeys at the National Center for Toxicological Research (NCTR) [4]. Through a separate process, at ACH, the children had been diagnosed as Attention Deficit Disorder (ADD), boarder line ADD, or healthy. Using the Self-Organizing Map neural network [1], the profiles of both healthy monkeys and children of varied ages with ADD were then generated and compared. The goal is to determine whether the animal model shares certain traits characteristics of ADD.
The Influence of Color-Enhanced and Graphical Information Presentation in Decision Making
Authors: Benbasat Isak , Dexter Albert S. , Todd Peter
Published: January 2007

Two experiments were performed to study students' ability to write recursive and iterative programs and transfer between these two skills. They wrote functions to accumulate instances into a list. Problems varied in terms of whether they were recursive or iterative, whether they operated on lists or numbers, whether they accumulated results in forward or backward manner, whether they accumulated on success or failure, and whether they simply skipped or ejected on failure to accumulate. Subjects had real difficulty only with the dimensions concerned with flow of control--namely, recursive versus iterative, and skip versus eject. We found positive transfer from writing iterative functions to writing recursive functions, but not vice versa. A subsequent protocol study revealed subjects had such a poor mental model of recursion that they developed poor learning strategies which hindered their understanding of iteration. It is argued that having an adequate model of the functionality of programming is prerequisite to learning to program and that it is sensible pedagogical practice to base understanding of recursive flow of control on understanding iterative flow of control.
Task-Action Grammars: A Model of the Mental Representation of Task Languages
Authors: Payne Stephen J. , Green T. R. G.
Published: January 2007

A laboratory experiment was conducted to assess the influence of graphical and color-enhanced information presentation on information use and decision quality in a simulation setting. This is the third in a series of studies examining the effects of colors and graphics in a managerial decision making task. The findings reported in this paper indicate that graphical presentations are more useful when evaluating information in order to determine promising directions in the search for an optimal solution bit when the task requires the determination of exact data values for computational purposes, graphical reports are less useful than tabular ones. Benefits of color include taking fewer iterations to complete the task. However, these benefits are associated more strongly with the graphical report as indicated by the significantly higher use of color enhanced graphical reports over monochromatic ones. The benefits of color are also restricted to the early stages in the decision task with color graphic report usage dropping sharply over time.
Softening Up Hard Science
Authors: Carroll John M. , Campbell Robert L.
Published: January 2007

Graphic displays of information are an important link in the design of user/machine interfaces. However, research on general effectiveness of graphic displays as information organizing formats for judgment and decision making has produced mixed results; graphic formats appear to facilitate judgmental performance in some contexts, but not in others. The two studies reported here examine the relative efficacy of a set of basic graphic display formats, such as might be used to summarize data in an information system, in the context of a task calling for individuals to integrate a set of information cues into an overall judgment. A "lens model" is used as a decompositional framework for represneting the relationship between the elements of the information displays and the psychological properties of the multi-cue judgment task. Combined results from the two studies suggest that judgmental performance is markedly enhanced or degraded by the degree to which the display format provides the user with an organizing structure that facilitates a matching between the relative importance of information and the psychological salience of the display's graphic features.
A Cognitive Model and Computer Tutor for Programming Recursion
Authors: Pirolli Peter
Published: January 2007

This paper aims at finding the optimal combination of written instruction and on-line practice for learning a new computer application. Experimental subjects learned commands for an electronic spreadsheet by reading brief user-manual descriptions and working training problems on-line. The form of the training problems was varied within subjects in order to control how much independent problem solving subjects engaged in while learning any given command. There were three forms of practice: (1) Pure Guided Practice, in which subjects were told exactly what keystrokes to type to solve the problems; (2) Pure Problem Solving Practice, in which subjects solved problems without guidance; and (3) Mixed Practice, in which the first problem for a command was presented in Guided Practice form and two others in Problem Solving form. The spacing of the training problems was also manipulated; the problems pertaining to a given command were either Massed (i.e., presented consecutively), or Distributed (i.e., separated by other instructional material). After a 2-day delay, subjects solved new problems on the computer without referring to the instructional materials. The results indicate that problem solving was a more difficult form of training than guided practice, but it produced the best performance at test. Distributing the spacing of training problems during training also improved performance at test. The results have clear pragmatic implications for the design of interactive tutorial manuals as well as implications for cognitive models of skill acquisition.
Computer-support cooperative work
Authors: Nielsen Jakob
Published: January 2007

At CHI'86 it was a general impression that the area of several people working together using computers was starting to become the next hot topic as a research area. At the same time the European Community is considering changing the focus of the human factors part of the next ESPRIT research program from the so-called
human factors-1
(interaction between a single human and a single computer) to
human factors-2
(interaction between several humans and several computers).
Applications of non-Markovian stochastic Petri nets
Authors: Fricks Ricardo M. , Puliafito Antonio , Telek Miklós , Trivedi Kishor S.
Published: January 2007

Petri nets represent a powerful paradigm for modeling parallel and distributed systems. Parallelism and resource contention can easily be captured and time can be included for the analysis of system dynamic behavior. Most popular stochastic Petri nets assume that all firing times are exponentially distributed. This is found to be a severe limitation in many circumstances that require deterministic and generally distributed firing times. This has led to a considerable interest in studying non-Markovian models. In this paper we specifically focus on non-Markovian Petri nets. The analytical approach through the solution of the underlying Markov regenerative process is dealt with and numerical analysis techniques are discussed. Several examples are presented and solved to highlight the potentiality of the proposed approaches.
Analysis of windowing mechanisms with infinite-state stochastic Petri nets
Authors: Ost Alexander , Haverkort Boudewijn R.
Published: January 2007

In this paper we present a performance evaluation of windowing mechanisms in world-wide web applications. Previously, such mechanisms have been studied by means of measurements only, however, given suitable tool support, we show that such evaluations can also be performed conveniently using infinite-state stochastic Petri nets. We briefly present this class of stochastic Petri nets as well as the approach for solving the underlying infinite-state Markov chain using matrix-geometric methods. We then present a model of the TCP slow-start congestion avoidance mechanism, subject to a (recently published) typical worldwide web workload. The model is parameterized using measurement data for a national connection and an overseas connection. Our study shows how the maximum congestion window size, the connection release timeout and the packet loss probability influence the expected number of buffered segments at the server, the connection setup rate and the connection time.
Book review: EXPERT SYSTEMS 85. Edited by Martin Merry (British Computer Society)
Authors: Campbell K.
Published: January 2007

Expert Systems 85,
edited by Martin Merry, contains the papers presented at the fifth technical conference of the British Computer Society's Specialist Group on Expert Systems. The conference covered a wide variety of topics ranging from general discussions of expert systems, applications, planning systems, uncertain inference, and knowledge representation. For the most part the authors assume some familarity with AI and expert systems although one does not need to be well versed in the area in order to follow the papers. Anybody with an interest in expert systems should be able to find at least a few papers worth reading in this collection. Both researchers and students would find this book interesting.
Expert Systems 85
may be helpful in broadening the horizons of those who are relatively new to the area and it would be especially appropriate as a source of supplemental readings for a graduate or undergraduate course.
Book review: Combinatorics, Set Systems, Hypergraphs, Families of Vectors and Combinatorial Probability by B. Bollobas (Cambridge University Press)
Authors: Marek W.
Published: January 2007

Can the distinct strengths of logic programming and functional programming be combined into a unified computational model? How can logic languages be extended to include functions and equations? The fourteen papers in this collection address these issues together with their underlying theory and semantics.
Book review: Annual Review of Computer Science Volume 1, 1986. Edited by Joseph Traub, Barbara J. Gresz, Butler Lampson, and Nils J. Nilsson (Annual Reviews, Inc.)
Authors: Lee Kenneth R.
Published: January 2007

Volume 1 of the
Annual Review of Computer Science
is the first in a series of annual publications by Annual Reviews, Inc. Intended to review the state of the art in computer science through a collection of review articles. This series represents the 27th such series by Annual Reviews (starting with the Annual Review of Biochemistry in 1932.)
Book reivew: A NATURAL LANGUAGE INTERFACE FOR COMPUTER-AIDED DESIGN by Tariq Samad (Kluwer Academic Publishers, 1986)
Authors: Sullivan Daniel
Published: January 2007

Tariq Samad's
A Natural Language Interface for Computer Aided Design
describes a parser developed as part of the author's doctoral thesis at CMU's Department of Electrical and Computer Engineering. The motivation for this work, i.e. to develop a natural language front end for a circuit-simulation program (SPICE), was pragmatic not theoretical. Samad's parser, CLEOPATRA, is not easily positioned in the large body of theory which has developed over the last two decades in natural language research; however, it does share some similarities with work in Conceptual Dependency Theory. Basically, he feels this application, because of its "complexity," requires a novel approach.
Graphical interface for logic programming
Authors: Monfroglio Angelo
Published: January 2007

Much of the power of PROLOG language and logic programming is due to the unification process between variables and the matching between patterns. Moreover reasoning and theorem proving is easily achievable through the logic and the backtracking mechanism of the language.
The symbolic computation laboratory at UIUC
Authors: Gray John W.
Published: January 2007

As I was leaving Erwin Engeler's office at the ETH during the summer of 1985, he casually asked me if I had seen their mathematics laboratory. Up to that point I had heard nothing about it, but as soon as I understood how it was organized and how it functioned, I realized that it was almost exactly what I had been looking for. Over the years, there have been numerous computer projects in the mathematics department at the UIUC, the most notable being George Francis' Apple Lab and the recently established Plato and Excel (IBM) labs. However, none of these seemed to conform with the kind of computer experience I imagined for students. I did not feel that it was the proper function of a mathematics department to teach students to program in traditional languages such as Basic or Pascal or Forth. But I did feel that algorithms were an important component of modern mathematics which deserved the same kind of emphasis that is normally accorded to proofs. What better way to understand the role of algorithms could there be than to try to implement them in computer programs? How could this be done unless it were done say in Pascal? Why not use Macsyma? I thought and still think that one could base a valid course just on this, but when I saw that the Laboratory at the ETH used projects in many different computer algebra languages, I realized that that was the methodology for which I was searching.
Burnside's theorem
Authors: Binger D.
Published: January 2007

This project was derived directly from Eva Gray's translation of project No. 001-001,
Satz von Burnside
, by E. Graf from ETH.
The rotation group of Rubik's cube
Authors: Knill O. , Mäder R. E.
Published: January 2007

In this project, the group theory program "Cayley" is used to solve some problems associated with Rubik's Cube, including the original problem of restoring the initial state of the cube.
Optimization on networks
Authors: Binger D.
Published: January 2007

The project is to use PROLOG to solve an optimization problem on a network. A brief introduction to networks includes the definitions necessary for the description of the optimal flow algorithm, which uses the painted network algorithm as a subroutine. An implementation of the painted network algorithm in PROLOG is given.
Public key encryption
Authors: Küchlin W.
Published: January 2007

The RSA method is used for the interchange of secret messages via insecure channels. It is elegant in theory and fast and reliable in practice. Applications are in the field of communication networks.The method is initialized by choosing some suitable large prime numbers. Encrypting and decrypting of a message are done by modular arithmetic. The modulus is a large integer (e.g. 200 decimal digits). Any attempt to break the system amounts to factoring the modulus.The basic operations that are needed for an implementation are fundamental for any computer algebra package, e.g. SAC-2 offers them in an suitable way. This project therefore requires only little programming, but some insight into theory and the ability to find and put together existing components. An optional part of the project deals with the security of the method.