bluuebunny/crossref_metadata_2025 huggingface dataset:
Constrained frequent pattern mining
Authors: Pei Jian , Han Jiawei
Published: January 2007

It has been well recognized that frequent pattern mining plays an essential role in many important data mining tasks. However, frequent pattern mining often generates a very large number of patterns and rules, which reduces not only the efficiency but also the effectiveness of mining. Recent work has highlighted the importance of the constraint-based mining paradigm in the context of mining frequent itemsets, associations, correlations, sequential patterns, and many other interesting patterns in large databases.Recently, we developed efficient pattern-growth methods for frequent pattern mining. Interestingly, pattern-growth methods are not only efficient but also effective in mining with various constraints. Many tough constraints which cannot be handled by previous methods can be pushed deep into the pattern-growth mining process. In this paper, we overview the principles of pattern-growth methods for constrained frequent pattern mining and sequential pattern mining. Moreover, we explore the power of pattern-growth methods towards mining with tough constraints and highlight some interesting open problems.
Incorporating clinical diagnoses in the prediction of performance on computer-based tasks for low vision users
Authors: Jacko Julie A.
Published: January 2007

Researchers focusing on investigations of human-computer interaction are developing a heightened awareness of the challenges that impede universal access to information technologies. Furthermore, researchers are acknowledging that low vision computer users represent a sizeable portion of the computing community for whom information technologies must be made available if we are to claim successful universal access.The low vision computing community represents a vast array of visual capabilities and limitations. Thus, it has been challenging for researchers to characterize this community in a meaningfully empirical way. As a result, research and design to-date have depicted low vision computer users as a single collection of individuals possessing comparable capabilities, limitations and needs. The danger is that researchers and designers overlook the individual differences in low vision computer users that render each of them more or less able to effectively utilize computing technologies.Investigations of human-computer interactions should include clinical profiles that capture the essence of the visual capabilities of the population in question. This will enable adequate representation of the individual differences that exist between low vision computer users. In addition, we must understand (Jacko & Sears, 1998):• how a person's visual profile drives system configuration choices,• how changes in one's visual profile motivate transitions from one configuration to another, and• how visual profiles drive the interaction strategies that are adopted during task execution.The author, a member of the ACM and Assistant Professor of Industrial Engineering at the University of Wisconsin-Madison, was awarded a five-year, $500,000 Presidential Early Career Award for Scientists and Engineers (PECASE) to investigate these and related issues in her research titled, "Universal Access to the Graphical User Interface: Design for the Partially Sighted." Jacko was one of twenty National Science Foundation (NSF)-supported researchers to receive the award.The research is a collaborative effort with ophthalmologists from the Bascom Palmer Eye Institute of the University of Miami School of Medicine, the Digital Signal Processing Laboratory at Florida International University, and The Miami Lighthouse for the Blind.
New technologies and people with disabilities
Authors: Leidermann Frank , Weber Harald , Zink Klaus J.
Published: January 2007

The Institute of Technology and Work at the University of Kaiserslautern/Germany is associated with the Chair of Industrial Management and Human Factors, headed by Prof. Dr. Klaus J. Zink. Despite the institutional frame as an University's Institute was just set in 1995 the research group took its first steps more than 10 years ago. Under the vision "to make a relevant contribution to link humanity and economy using integral approaches" it was strived to improve the working conditions of people with disabilities. Whereas the emphasis within the first years of work was laid on sheltered workshops for people with disabilities, meanwhile the focus has expanded and now includes very different forms of occupation that support or enable vocational integration.Today the Institute is divided into the two divisions ,,Health Care & Social Institutions"and ,,Manufacturing & Service Industry". This presentation will only focus on the first division.
A pilot study to examine the mobility problems of visually impaired users travelling the web
Authors: Harper Simon , Goble Carole , Stevens Robert
Published: January 2007

The Towel project seeks to find solutions to problems encountered by both visually impaired and sighted users when travelling in the World Wide Web by leveraging solutions found in real-world mobility and applying them to the virtual world. Visually impaired users find mobility on the Web particularly difficult because of the reliance of hypermedia on visual layout and large viewable areas that facilitate and enhance sighted mobility. Hypertext design and usability has traditionally concentrated upon navigation to facilitate this mobility; consequently other aspects of travel are neglected and web mobility has suffered. Similarly, the Web Accessibility Initiative (WAI) Guidelines do not take a holistic view of travel and therefore in both these cases a fully rounded view of mobility cannot be formulated. This paper presents the basis for these assertions by drawing analogies between real-world and virtual-world mobility, and then attempts to substantiate these analogies by conducting a pilot study of virtual mobility on a focus group of both sighted and visually impaired web users. Knowledge of the differences in travel between visually impaired and sighted people will enable the design of better user agents and web content for visually impaired users as well as the sighted community.
Agent behavior and agent models in unregulated markets
Authors: Smith K. , Paranjape R. , Benedicenti L.
Published: January 2007

Mobile-agent systems show significant promise as the most effective way to harness the power of the Internet and the massive collection of information and opportunity that the Internet holds. However the efficient organization and control of these systems remains one of a number of unsolved problems with this approach to network computing. This paper examines a mobile-agent system with specific focus on environment sensing, preemptive load balancing and open agent markets. Agent behaviour is studied with actual agent systems using progressively sophisticated agent migration strategies.It is shown that actual modeling shows interesting and difficult to predict behaviour in the agent systems. It is shown that mobile agents with relatively simple migration strategies can cause loads in self-regulating agent markets to oscillate. It is further shown that using Autoregressive modeling to predict the market behaviour can allow individual agents to significantly outperform other agents. However the fidelity of the model is critical to the success of the agents. The criticality of good agent strategies and actual agent system modeling is thus highlighted.
Scalability and information agents
Authors: Deters Ralph
Published: January 2007

Having fast and dependable access to the most relevant information available is of the utmost importance in a competitive information-oriented society. Ensuring transparent and dependable access to a large number of heterogeneous, ill-structured and often distributed data and information sources is a complex problem with many different facets. Over time a large variety of very different approaches have been developed. Among the many competing approaches, information agents seem to be particularly well suited to the challenges of the information cyberspace due to their highly adaptive and distributed problem solving. Only information agents seem capable to offer the much needed user centric access to the myriads of data and information sources accessible via the web. But just like other agents, they require significant computational resources making it difficult to build scalable systems.This paper has two aims. First it is an attempt to draw attention to the scalability challenges in developing systems consisting of large numbers of information agents. Second, it presents a CORBA based framework called DICE for building information agents and reports about its use in developing real world systems based on information agents.
Distributed control and distributed computing
Authors: Mukhopadhyay Snehasis
Published: January 2007

Distributed control algorithms strive to achieve coordination between physically distributed decision-makers and controllers in order to realize some desired behavior of a large-scale system in a fast, stable and accurate manner. However, these methods almost invariably make idealization assumptions concerning the reliability and correctness of the underlying distributed computing system which is used to implement algorithms. When these assumptions are not fully met practice, it may cause substantial and even qualitative changes in the performance of the overall distributed control system. This article discusses the effects of two of the distributed computing issues (
i.e.,
synchronization and communication delays) on the performance of a real-time decentralized adaptive control algorithm.
An array-oriented (APL) wish list
Authors: Lucas Jim
Published: January 2007

The fundamental, data structure in APL is the array. Arrays are, in most APL dialects, the only data structure, from scalars as arrays with no dimensions to the complex structures of nested arrays. But there are other ways in which array concepts could be applied, yet so far they have not. These are the top items on my "Array-Oriented Wish List".Less fundamental---but far easier to implement---should be certain operators and functions I propose, which I think would enhance the power of existing array operations. Some of these already exist in one or more dialects of APL, and I think all would benefit if they were universally adopted.In this suite of proposals, some are general, others more specific, and some could interact with each other in positive synergy, but none of them requires any of the others to be useful. In some cases, I suggest potential variants, each reasonable in its own right.The purpose of this paper is to present the concepts. In most cases, I don't attempt to go into details of implementation. That would require a much more extensive treatment of each concept. I hope that others---especially implementers---might take up the challenge.
Array form representation of idiom recognition system for numerical programs
Authors: Hiroyuki Sato
Published: January 2007

Today, PSE emerges as a promising approach for providing programmers with high-level abstract functions Particularly for numerical programs which essentially handle large arrays, abstract representation of array-handling functions is very important. Idiom recognition can be a bridge between abstract source programs and concrete architectures. It can remove obstacles of gaps between the two that cannot be bridged by today's state of the art compilers. A major problem in idiom recognition is intermediate representation. This paper applies term rewriting theory---a very general framework --- to an idiom recognition system. Specifically, we apply it to the idiom recognition problem of Fortran90/95 matrix manipulations, and show that the Fortran90/95 system is never a trivial system. Straight forms are introduced to make the idiom recognition system more powerful. We make a completion procedure based on this Fortran90/95 system, and show some non-trivial idiom recognition using our theory.
Classification trees in APL
Authors: Skomorokhov Alexander , Kutinsky Vladimir
Published: January 2007

This paper considers the problem of classification tree based data analysis. Among the topics discussed in the paper are: growing a classification tree using CART style exhaustive search for splits, selecting the right size for the tree using minimal cost-complexity cross-validation pruning, and examples of the application of classification trees.The algorithms are implemented in Dyalog APL.Application example is based on data from vibration monitoring equipment installed on a Nuclear Power Plant in Novovoronehz, Russia and includes classification of vibration spectra of steam generators or coolant pumps and classification of vibration spectra of steam generators of different coolant loops.
Suggestions for a method of analyzing binary images using Langlet's parity logic
Authors: Smith Stuart
Published: January 2007

This paper describes an extension to the system of parity logic operations developed by Gerard Langlet and subsequently elaborated by Michael Zaus. Two operations,
A
and
B
, are introduced which can be used both to analyze and to synthesize arbitrary patterns of l's and O's in square Boolean matrices. The
A
and
B
operations are, like most of the operations in Langlet's system, completely reversible (i.e., the input to
A
or
B
can be exactly reconstructed its output). The
B
operation is shown to be connected with Langlet's Helical and Cognitive transforms. Manipulations of binary images are used to illustrate the properties of
A
and
B
, but no claim made that they have real-world applications at this time. The
A
and
B
algorithms, their supporting operations, and the programming examples are in Q'Nial; however, they can be easily translated APL, J, or other may programming language.
A canon for the representation of multivariate arrays in the APL2 computing language
Authors: Stockbridge Richard Drexel
Published: January 2007

A uniform structure for multivariate data constructs that employs the nested array features of
APL2
has been successfully developed and implemented. This Array Canonical Form (
ACF
) succinctly describes its own contents, an important feature for the
APL2
functions and operators that accept
ACF
arrays as arguments. An extensive library of
APL2
procedures has been created over the course of many years and projects to perform routine as well as specialized analytical, archival, descriptive, and graphical operations on any
ACF
. A self-describing uniform array structure is useful for satisfying requirements of reusable, common code and for requiring self-documentation of multivariate data. The
ACF
structure described in this paper satisfies these requirements in a concise, logically intuitive elemental structure that depends upon and fully utilizes the
APL2
language features for nested array construction and manipulation.
What's wrong with APL2
Authors: Brown James A.
Published: January 2007

Design of a programming language is both an art and a science. A notation must be formally correct yet usable. Formal correctness is subject to rigorous analysis but usability is more difficult to measure. If there was only one correct formalism, language design would be easy --- identify the correct notation, implement it, and use it. Unfortunately there are many correct notations and reasonable people may have differing opinions as to which is more usable. This paper will discuss some features of APL2 which, while not exactly wrong, might have been more useful had a different choice been made. Unfortunately this is quite a short paper.
APL tutorial in mathematical modelling
Authors: Buzin A. , Naftulin I.
Published: January 2007

The software presented below is a computer tutorial in mathematical modeling. The term "Mathematical Modeling" does not have a precise definition. We use the term to imply problem description in mathematical terms and the use of mathematical tools to investigate the given problem. For example, by using differential equations it is possible to describe a vast variety of different phenomena in the areas of physics, biology, sociology, etc. Some types of differential equations can be solved analytically, others require numerical methods and a computer. So today's mathematical modeler should be prepared to use a computer as an accessory.There are a great number of software packages allowing mathematical models to be studied numerically as well as analytically. Among these packages are MatLab, MathCad, Maple, Mathematica and others. However, students of Applied Mathematics should not only know how to apply numerical methods but also understand their principles and the limits to their application. Therefore, any student class in Numerical Methods should include some coding of numerical methods by using a programming language.Classical programming languages are overburdened with ritual operations (data description, cycles, manual distribution of memory) to such an extent that after programming the numerical method very little time is left to investigate the method itself: its behavior with different parameters and in different sorts of problem. Moreover, the object known as a "program" in a classical programming language is something monolithic; there are very few useful operations defined over such objects. Therefore APL enjoys a considerable advantage over classical programming. It allows students to concentrate on the algorithm itself and not on the data description.But one faces some disadvantages when using APL. APL does not provide for alternative representations of numbers or for the creation of standalone executable modules.The tutorial presented below is a program having a Windows interface which lets students familiarize themselves with the Theory of Calculation and problem solving in connection with numerical methods or actual models.The tutorial consists of lectures, problems, hints and solutions, plus a library of numerical methods. But most importantly, when using this tutorial, students can solve problems in the actual tutorial environment, i.e. the APL session and the GRAN subsystem for interactive graph plotting are available for the student's use.The tutorial below is not up to commercial standards, but is intended only as an illustration of APL's capabilities as a teaching tool. Clearly, this tutorial could be adapted to a variety of disciplines and this is a course of action we hope to pursue. In accordance with APL's history, this tutorial is an individualized and personalized study-aid and not a product for mass consumption.
The design and implementation of an APL dialect, ELI
Authors: Ching Wai-Mee
Published: January 2007

ELI is an APL dialect that uses ASCII characters. It has a workspace based programming environment: all primitives of APL1[3] and control structures. It has no nested arrays or defined operators. Instead, it has user-defined data structures, and defined functions can take functions (in addition to variables) as parameters. ELI preserves the simplicity of APL1 while modestly extends it. The ELI interpreter is implemented on Windows using Visual C++, which connects to MFC to provide many GUI functions for the Window platform. The core interpreter consists of a parser, a tree-executor, and a module implementing all primitive functions. Currently the implementation also provides a function editor and the ability to save/load workspaces.
An improved method for creating dynamic web forms using APL
Authors: Halasz Steven J.
Published: January 2007

The subject of this paper is "active" or "dynamic" web forms handled by Dyalog APL running on a web server. With "active" web forms, the HTML which specifies form controls is generated dynamically by a server program, in contrast to "static" web forms in which the HTML is fixed and does not vary from one page hit to the next. Also, I will be discussing only "thin client" approaches which minimize the amount of code which runs on the client machine. The method shown, which I call a "standard template" method, allows source pages to be maintained with visual tools such as Macromedia Dreamweaver and minimizes the amount of coding required when new forms are created in the same general format.
SPARROW-a speech and knowledge based architecture for a workplace
Authors: Marzi Ruth
Published: January 2007

An architecture is presented, which for complex office-systems makes use of speech-processing as well as various methods from artificial intelligence in order to increase the acceptance of such systems. Support can only be useful if it is twofold: the end-user has to be supported in his daily tasks, but the ADE (application development engineer) also needs a tool to support him in the difficult task of configuring a work-place system and keeping it up to date, since the requirements on his qualifications span a wide area.
A knowledge discovery method
Authors: Skomorokhov Alexander O.
Published: January 2007

The paper concentrates on one direction of Knowledge Discovery in Data Bases and Data Mining, known as automatic rule extraction from data sets.The rule extraction algorithm has been implemented in Dyalog APL. The paper presents APL functions and tests made on artificial data sets.The real life problem solution is described as an application of implemented APL code. The problem is to find automatically rules to describe the corrosion rate of steel in sodium as a function of alloy additions. The input data are experimental data of corrosion rate measured for different steel samples. The output is a set of IF-THEN rules, which describe the dependence of corrosion rate on alloy additions. An expert in corrosion has validated the rules and an example of real "discovery" has been mentioned.
An interface between Java and APL
Authors: Symes Mike
Published: January 2007

This paper discusses an interface between the Java and APL languages. It is in the form of a report on some technology that has been developed for SHARP APL, though there are no aspects of the technology that are particularly special to that dialect of APL.The interface (called, for the purposes of this paper, the "APL-Java Interface") is a general facility for allowing APL programs and Java programs to work together. The project was started because it occurred to us that there is now a substantial body of Java-based technology that solves many of the problems that we needed to address for APL, particularly in the area of program interoperability; and, since this Java-based technology is both widely (and, in many cases, freely) available, and portable across the platforms that are of most concern to us, it would make a lot of sense to try to develop a general way to access this technology from APL. If that could be done, we could largely avoid re-inventing the wheel in a whole set of instances, by capitalizing on existing Java-based solutions. As a simple example, rather than implementing the standard XML parser in APL (which is certainly possible), we could simply use one of the several existing Java implementations.There are four parts to this paper:• A very brief discussion of Java is given.• An overview of the APL-Java Interface is presented, with some examples.• Some practical uses for the interface are presented.Some aspects of the interface that are of some technical interest are discussed.• The dialect of APL used in code examples in this paper is SHARP APL.A knowledge of Java will certainly help with this paper, but the dependency on such knowledge is not all that heavy, so it is quite likely that most of the paper's points can be grasped given just the few simple Java notions listed below.
Comparative file I/O methods in APL2
Authors: Wheeler Nancy
Published: January 2007

This paper will discuss the state of file I/O in APL2. The intent is to educate the readers on the options open to them so that they can choose the file I/O method most suitable for their needs.Topics will include evolution of file I/O over the years, current status on a platform-by-platform basis, mainframe to workstation migration issues, suitability of the different methods available for various tasks, and performance notes.
The "full polymorphic package" (FPP)
Authors: Forest Etienne , Schmidt Frank
Published: January 2007

In this short note we present a Fortran 90 attempt at creating a polymorphic Power Series/Double Precision type. This type came "alive" in our Full Polymorphic Package or FPP. This work was then followed by the creation of a simulation code for accelerator physics called the "Polymorphic Tracking Code" (PTC code). The presence of a polymorphic Real/Taylor type is motivated by the realization that all of standard accelerator theory can be efficiently described in terms of maps describing propagation for a finite time.
Location errors in wireless embedded sensor networks
Authors: Slijepcevic Sasha , Megerian Seapahn , Potkonjak Miodrag
Published: January 2007

Wireless sensor networks monitor the physical world by taking measurements of physical phenomena. Those measurements, and consequently the results computed from the measurements, may be significantly inaccurate. Therefore, in order to properly design and use wireless sensor networks, one must develop methods that take error sources, error propagation through optimization software, and ultimately their impact on applications, into consideration. In this paper, we focus on location discovery induced errors. We have selected location discovery as the object of our case study since essentially all sensor network computation and communication tasks are dependent on geographical node location data. First, we model the error in input parameters of the location discovery process. Then, we study the impact of errors on three selected applications: exposure, best- and worst-case coverage, and shortest path routing. Furthermore, we examine how the choice of a specific objective function optimized during the location discovery process impacts the errors in results of different applications.
An aggressive approach to failure restoration of PCS mobility databases
Authors: Wang Tsan-Pin , Tseng Chien-Chao , Chou Wen-Kuang
Published: January 2007

In Personal Communications Services (PCS) networks, subscribers' current locations are usually maintained using a two-level hierarchical strategy with two types of databases, specifically, VLRs and HLRs. Location records might be lost due to the malfunction of mobility databases. GSM uses aggressive restoration to restore the HLR data from the VLRs. However, previous work on aggressive restoration is based on periodic checkpointing and might not be feasible in general. This paper proposes a novel aggressive approach, based on aperiodic checkpointing, to back up HLRs and VLRs. The aperiodic checkpointing scheme could use the number of uncheckpointed location records as the threshold value to trigger a backup process. Performance analysis shows that aperiodic checkpointing is more feasible than periodic checkpointing for aggressive restoration.
Mobility and performance modeling in cellular communication networks
Authors: Camarda P. , Schiraldi G. , Talucci F. , Valla R.
Published: January 2007

In this paper, we will show a simple analytical model for cellular communication networks performance evaluation. The model assumes a finite population of mobiles moving in a finite number of cells. A model of this type allows us to evaluate the effects on system performance of the following factors: Fixed Channel Allocation (FCA) scheme, user load, mobility and distribution of users among cells. Numerical simulation experiments show that predictions of this simple model are acceptable in a wide range of mobility and for light to moderate load conditions. A discussion about these assumptions will show that this model is well suited for future pico-cellular system analysis.
Packetized voice transmission using RT-MAC, a wireless real-time medium access control protocol
Authors: Baldwin Rusty O. , Davis Nathaniel J. , Midkiff Scott F. , Raines Richard A.
Published: January 2007

RT-MAC is a simple, elegant, and robust medium access control (MAC) protocol for use in transmitting real-time data in point-to-point
ad hoc
wireless local area networks (WLANs). Our enhancement of IEEE 802.11, real-time MAC (RT-MAC), dramatically reduces missed deadlines and packet collisions while increasing throughput by selectively discarding packets and sharing station state information. For example, RT-MAC is able to successfully transmit 40 2-way voice conversations in addition to a normalized offered load of 80%. IEEE 802.11 is only able to transmit 10 2-way conversations under the same conditions. In another instance, RT-MAC reduced packet collisions from 50% to less than 15% while increasing throughput by more than 50%. Herein we extend our previous performance analysis of RT-MAC to include integrated voice-data transmission. Stations using RT-MAC are interoperable with stations using IEEE 802.11 and show a significant performance improvement even when a minority of stations in the network employ RT-MAC.
Mathematical notation, APL and programming languages
Authors: Smillie K. W.
Published: January 2007

This paper gives a few remarks on the development of mathematical notation and on some of its principal characteristics in its present form. It then gives by way of contrast the main features of
APL
as a notation. The birthday problem is discussed using
APL
as a notation, and a defined function is derived from this analysis. Finally, the conversion of functions to programs in other languages is discussed briefly, and a Fortran program for the birthday problem is given as an example.
Extension of APL primitive functions to the complex domain
Authors: Penfield Paul
Published: January 2007

Many APL primitive functions can be extended to the domain of complex numbers. In some cases the generalizations are not straightforward, and two or more design choices are considered. This paper is intended to stimulate a discussion in the APL community of the possible design choices before the first implementation of complex APL renders such a discussion academic. This paper is the second in a series of three papers; the first was reference [1].
Complex APL
Authors: Penfield Paul
Published: January 2007

Results of discussions within the APL community about how APL should be extended to complex numbers are presented.
Thoughts concerning the index origin
Authors: Jochman D.
Published: January 2007

In a clear APL workspace, the index origin equals 1. This paper explores the consequences of making the index origin equal to 0.
Some notes on handling errors in APL
Authors: Burrill James H.
Published: January 2007

This paper explains the original method used at the University of Massachusetts for allowing APL programs to handle their own errors (Section 1). It then discusses the changes that were made to improve the method (Section 2). Remaining problems are discussed in Section 3.It is not the purpose of this paper to convince the reader that the facilities discussed here are needed. This has been addressed elsewhere [1, 2, 3].This paper was first presented informally at the Queen's APL Workshop, Queen's University, Kingston, Ontario, Canada (May 1976). It was revised in October 1977.
The socio-technical beginnings of APL
Authors: McDonnell E. E.
Published: January 2007

This paper gives some of the history of the early implementations of APL, and concentrates on the system aspects of these implementations, paying special attention to the evolution of the workspace concept, the time-sharing scheduling strategy, and the handling of the terminal. It contrasts the development of APL with the development of other time-sharing systems which were being built at the same time.
Aplanar, two-dimensional geometry in APL
Authors: Porter G. J.
Published: January 2007

The algebraic and array-value orientations of APL make it a very desirable language to use for geometry. A point is given by its coordinates, a line by its endpoints, and more generally, a polyline or stroke by an ordered collection of N points. These are all arrays. More complicated pictures can be created as a union of these elements.In this note we describe a workspace, APLANAR, for two-dimensional (planar) geometry. This workspace is used in conjunction with a viewing system (graphics package) to produce graphic output. The viewing system is described in Appendix II.
Representation and manipulation of finite sets
Authors: McAllister B. L.
Published: January 2007

A set may be represented in APL either through a vector of its elements, through a Boolean vector representing its characteristic function with respect to a pre-specified universal set, or through the re-interpretation of this Boolean vector as the binary representation of an integer. This paper discusses the use of these representations for manipulation of sets, collections of sets, and functions as they are used, for example, in topology.
An ASCII notation for APL
Authors: Crick Michael F. C.
Published: January 2007

The increasing use of 120-cps terminals and the growth of APL are placing increasing strains on current APL notation. For those people who think verbally rather than visually, a phonetic notation is preferable to a logographic notation. A notation is proposed for use specifically on ASCII terminals. Specific solutions are offered to the problems of (a) ambiguities in parsing (upper and lower case), (b) recognition of operator sequences (periods as separators), and (c) reserved-word name conflicts (name spaces). The change in notation is accomplished with almost no change to the underlying language.
Modeling and simulation in the VLSI environment
Authors: Sachar Howard , Feretich Robert A.
Published: January 2007

This paper discusses the use of APL to model VLSI chips as part of an initial design. Starting as a data flow, the design is partitioned and sliced into functional units that can be contained within a VLSI chip. By linking these APL models together, it is possible to simulate the overall implementation and find critical paths.
Redefining reduction along an empty axis
Authors: Hoskin Zeke
Published: January 2007

This note presents a consistent approach to evaluating the reduction of an array along an empty axis, giving results which agree with accepted values where these exist and also giving unique and consistent results for the Nand and Nor functions.Note: For clarity, the body of this paper deals only with vectors; the extension to higher-rank arrays is straightforward.
Processing structure declarations with APL
Authors: Kellerman Eduardo
Published: January 2007

APL is sometimes used for processing data that have been created as a structure defined by a Declare-statement in PL/I-related languages; particularly when the data are obtained from a file. When the structure of the data is complex, it is time-consuming manually to create APL code to break up the data into its constituent parts. This article describes a method for converting structure declarations into a form usable by APL functions.
An easily built APL editor
Authors: Robson Robert
Published: January 2007

A full-screen editor has been built as an APL program employing a full-screen auxiliary processor, requiring no modification of the APL system. It is designed to be easy to construct and use on any system with such capabilities.The user is provided with a comprehensive set of editing functions as well as several features specific to editing APL functions. The editor is capable of editing any APL function or rank-2 variable in the workspace. Facilities are provided to allow the user easily to extend the capabilities of the editor.
A trace facility for intelligent terminals
Authors: Luzi Andrew D.
Published: January 2007

Intelligent terminals require numerous, complex, non-descriptive codes to implement their extensive capabilities. This article describes a trace facility written in APL that transforms these codes into readable trace reports. These reports are useful in debugging and documenting those applications programs that use intelligent terminals extensively.
Implicit instead of the explicit copy command
Authors: van Batenburg F. H. D.
Published: January 2007

If one prefers to include all required programs together in one workspace, the necessary programs could, as usual, be retrieved from other workspaces by the explicit copy command and stored together in the same workspace. However, there are a number of reasons why one would like to have some necessary programs or variables residing in their original workspace. Therefore a useful enhancement in order to use those objects in their original position would be the
implicit copy
where a qualified name is used in the header. This qualified name is the pure name preceded by its workspace library reference. The result should be the creation of a temporary local environment, followed by a copy of that object from the referred workspace.
Disk scheduling policies with lookahead
Authors: Thomasian Alexander , Liu Chang
Published: January 2007

Advances in magnetic recording technology have resulted in a rapid increase in disk capacities, but improvements in the mechanical characteristics of disks have been quite modest. For example the access time to random disk blocks has decreased by a mere factor of two, while disk capacities have increased by several orders of magnitude. High performance OLTP applications subject disks to a very demanding workload, since they require high access rates to randomly distributed disk blocks and gain limited benef£t from caching and prefetching. We address this problem by re-evaluating the performance of some well known disk scheduling methods, before proposing and evaluating extensions to them. A variation to CSCAN takes into account rotational latency, so that the service time of further requests is reduced. A variation to SATF considers the sum of service times of several successive requests in scheduling the next request, so that the arm is moved to a (temporal) neighborhood with many requests. The service time of further requests is discounted, since their immediate processing is not guaranteed. A variation to the SATF policy prioritizes reads with respect to writes and processes winner write requests conditionally, i.e., when the ratio of their service time to that of the winner read request is smaller than a certain threshold. We review previous work to put our work into the proper perspective and discuss plans for future work.
A WordNet interface to APL2
Authors: Alfonseca Enrique
Published: January 2007

Lexical ontologies have proven a very useful tool for natural language processing, specially where some semantic analysis is necessary. One of the most widely used is WordNet [Miller, 1995]. In this work, we describe an implementation of WordNet that extends its initial functionalities, and which is directly accessible from APL2. The interface is very simple, as only a few functions and one operator are sufficient to use all the capabilities of WordNet.
Out-of-control structures
Authors: Lucas Jim
Published: January 2007

The proponents of Control Structures
1
claimed that adding them to APL
2
would improve both the organizational structure and the readability of APL code, but in my experience this has
not
occurred. Instead, I find previous obstacles to readability have often simply been supplanted by different obstacles and prior forms of structural awkwardness by new architectural excesses.It appears to me that some of these changes
3
represent a loss of "APL-ness" in coding style, specifically those characteristics of conciseness, modularity, and linearity.This paper discusses specific changes in style and the difficulties I feel they create, and then presents various proposals for improving the situation. The ideas presented are illustrated with examples taken from actual code written by professional APL programmers.
4
Looking back on looking ahead
Authors: Lucas Jim
Published: January 2007

At the APL90 Conference I presented a paper (
Programming Ecology,
or
APL and the World at Large)
in which I suggested that APL's future was dependent on its becoming an integral part of a wider computing environment, and in it I made a number of proposals for accomplishing this. Comparing my analysis and proposals to how both APL and its environment have actually evolved in the intervening dozen years is both interesting and instructive, inspiring a mixture of celebration, trepidation, and sober reflection.
An interface for user-defined functions in a database application
Authors: Mansour Stephen M.
Published: January 2007

This paper describes a database application, which permits users to write their own functions in a limited way using a scripting language consisting of a set of canned functions written in APL. Inputs to the function can be database fields and/or constant values. This provides users with additional flexibility in generating reports and selection statements.The user must first define the function inputs and outputs assigning names, position, data types, default values and descriptions for each. Then the user writes a script in the database language, making reference to the named input and output fields. The scripting language is limited to a defined set of functions and certain ASCII symbols.A limited set of control structures are permitted, such as if-then-else, and while loops.The application consists of an editor, which allows the user to describe the inputs and write the script, and a "compiler", which generates an APL function, which behaves in a similar manner to the canned functions, provided with the database application. The "compiler" inserts data assignment and input checking into the function based on the data type and data structure permitted by the user.
Delivering power with minimal restraint
Authors: Mitchell David
Published: January 2007

Networked computers have been used for over 30 years. APL has been part of that environment from the beginning. One key value APL has always provided is the ability for individuals and groups to be independent of complex, centralized administration.Today, APL continues to excel in that role. New technologies often require centralized administration of services such as Web page development and publishing, report printing and distribution, Web based interactive applications and Web enabled data delivery.We have been able to provide these types of services in a way that allows users connected worldwide to a singe APL system to develop, test and distribute data and applications with a minimum of overhead and central control. This paper will discuss four areas of services and several applications in each area.The four areas are:1. Web Mapped APL Files.These allow any user that can create and manage an APL file to create a Web site and distribute non-interactive data.2. Global Print Distribution via FTP.This facility allows any network user to define their PC, Workstation or Server to the APL FTP delivery system. Once defined, reports can be automatically FTPed to their PC from any corporate network host, not just the APL host.3. Parameterized Interactive Web Applications.This is a Web metasystem that allows any APL user to define an interactive Web site using a centralized Web server based in APL. Once the initial registration is complete, the user is free to change or expand their web application using simple, but powerful tools.4. Application-to-Application Systems.These are applications that require custom software on both the server and client systems. These offer the most tailored user interface, but require the most sophisticated programming, in general.
SAPL
Authors: Otto Tilman P.
Published: January 2007

The SAP company (Walldorf / Germany) provides a software interface for its R2 and R3 products called "Remote Function Call" (RFC). This interface is available on multiple operating systems and allows external systems written in C or C++ to directly call function modules of a R2/R3 system. In addition, it is even possible to provide external server function modules within an external system, which can be accessed from within the SAP system. This paper presents the newly developed RFC based APL extension "SAPL" that allows writing client and server applications for SAP systems entirely in APL. SAPL is the bridge between the powerful multi-dimensional data processing capabilities of APL and SAP based business applications.
Porting the parallel array programming language ZPL to an embedded multicomputing system
Authors: Rey Demetrio , Stubblefield Joss , Canning James
Published: January 2007

This paper describes the port of the ZPL parallel array language to the Mercury-RACE, a multicomputing system designed for embedded real-time applications. We discuss the design of the language runtime system and our strategy on mapping ZPL operators to hardware communication. We also show performance results of the ZPL parallel matrix inverse algorithm on the target architecture.
Evolutionary discovery of algorithms as circuits for quantum computers
Authors: Surkan Alvin J. , Khuskivadze Amiran
Published: January 2007

This paper demonstrates an application of an evolutionary approach for solving a class of non-trivial, hardware-design problems. Array processing features of the computer language APL simplify the implementation of an evolutionary solution in which simulation is performed by a genetic algorithm on a population of candidate solutions until one or more are satisfactory quantum algorithms. The objective of the simulation model is the automatic discovery of quantum computer algorithms. The algorithms are expressed in a circuit model that specifies the sequences in which quantum operators are to be applied. The automatically configured circuits operate as quantum computers that for the present have their domains of application limited to evaluation of only a few specific functions. The simulations use a small collection of basic and relatively low-level operators to obtain perfect results for five different target functions. These functions were chosen to demonstrate how, on a personal computer, an evolutionary method is able to discover novel designs of computing hardware. The results establish that it is feasible to use genetic algorithms in an evolutionary method to invent correct hardware designs. The progress of simulated evolution is directed by input/output constraints and a fitness function. Alternative configurations of circuit models can obtain algorithms with promise for future quantum computers. Current simulations yield primitive quantum algorithms with a total of twelve or fewer inputs and outputs. The discovered algorithms produce the correct results for evaluating the five selected logical and arithmetic functions.
Dynamic graphic regression
Authors: Sykes Alan M. , Mayer Alan D.
Published: January 2007

Statisticians and data analysts have always used pictorial representations of data (graphs and charts) to discover and explore relationships between variables, and to communicate their results to other people. Developments in computer hardware and software have now brought dynamically interactive graphs to everyone's desktop.
Dygress
(Dynamic Graphic Regression) is a statistical analysis toolkit which brings together a powerful combination of the new graphic tools and a wide range of regression techniques, and makes them easily accessible to the user.
Random behavior: mechanical and psychological
Authors: Lindley Foster
Published: January 2007

To continue an earlier discussion of random number generators in SIMULETTER (Vol 8, No 1, pp. 10--37), it is frequently said of the sequences produced by random number algorithms that they are not genuinely random, but rather, pseudo-random. Two reasons are given; a) the sequence is predictable and repeatable, b) each number is dependent on the preceding number. Yet the first reservation would hold for any gambling device and the second may be true without affecting the randomness of its output.
Uniformity tests on the GPSS-Fortran pseudorandom number generators
Authors: Janssens Gerritt K.
Published: January 2007

A fundamental characteristic of pseudorandom number generators is their uniformity. often in simulation packages the user has to accept the generators provided and has no control on their quality. GPSS-FORTRAN however is a package of FORTRAN-subroutines in which the generators are clearly presented to the user. In this paper we test the 30 generators available, warn the users not to use some of the generators for prespecified sample sizes and create a table containing the best available generators for the same sample sizes.