ppxscal/embedding_network huggingface dataset:
An Experimental Comparison of the Nearest-Neighbor and Nearest-Hyperrectangle Algorithms
Authors: Dietrich Wettschereck, Thomas G. Dietterich
Venue: Machine Learning (1995)

Algorithms based on Nested Generalized Exemplar (NGE) theory (Salzberg, 1991) classify new data points by computing their distance to the nearest &ldquo;generalized exemplar&rdquo; (i.e., either a point or an axis-parallel rectangle). They combine the distance-based character of nearest neighbor (NN) classifiers with the axis-parallel rectangle representation employed in many rule-learning systems. An implementation of NGE was compared to the k-nearest neighbor (kNN) algorithm in 11 domains and found to be significantly inferior to kNN in 9 of them. Several modifications of NGE were studied to understand the cause of its poor performance. These show that its performance can be substantially improved by preventing NGE from creating overlapping rectangles, while still allowing complete nesting of rectangles. Performance can be further improved by modifying the distance metric to allow weights on each of the features (Salzberg, 1991). Best results were obtained in this study when the weights were computed using mutual information between the features and the output class. The best version of NGE developed is a batch algorithm (BNGE FWMI) that has no user-tunable parameters. BNGE FWMI's performance is comparable to the first-nearest neighbor algorithm (also incorporating feature weights). However, the k-nearest neighbor algorithm is still significantly superior to BNGE FWMI in 7 of the 11 domains, and inferior to it in only 2. We conclude that, even with our improvements, the NGE approach is very sensitive to the shape of the decision boundaries in classification problems. In domains where the decision boundaries are axis-parallel, the NGE approach can produce excellent generalization with interpretable hypotheses. In all domains tested, NGE algorithms require much less memory to store generalized exemplars than is required by NN algorithms.
Task Clustering and Scheduling for Distributed Memory Parallel Architectures
Authors: Michael A. Palis, Jing-Chiou Liou, David S. L. Wei
Venue: IEEE Transactions on Parallel and Distributed Systems (1996)

This paper addresses the problem of scheduling parallel programs represented as directed acyclic task graphs for execution on distributed memory parallel architectures. Because of the high communication overhead in existing parallel machines, a crucial step in scheduling is task clustering, the process of coalescing fine grain tasks into single coarser ones so that the overall execution time is minimized. The task clustering problem is NP-hard, even when the number of processors is unbounded and task duplication is allowed. A simple greedy algorithm is presented for this problem which, for a task graph with arbitrary granularity, produces a schedule whose makespan is at most twice optimal. Indeed, the quality of the schedule improves as the granularity of the task graph becomes larger. For example, if the granularity is at least 1/2, the makespan of the schedule is at most 5/3 times optimal. For a task graph with n tasks and e inter-task communication constraints, the algorithm runs in $O(n(n\ l{\sl g}\ n + e))$ time, which is n times faster than the currently best known algorithm for this problem. Similar algorithms are developed that produce: (1) optimal schedules for coarse grain graphs; (2) 2-optimal schedules for trees with no task duplication; and (3) optimal schedules for coarse grain trees with no task duplication.
Algorithm 763: INTERVAL_ARITHMETIC: a Fortran 90 module for an interval data type
Authors: R. Baker Kearfott
Venue: ACM Transactions on Mathematical Software (TOMS) (1996)

Interval arithmetic is useful in automatically verified computations, that is, in computations in which the algorithm itself rigorously proves that the answer must lie within certain bounds. In addition to rigor, interval arithmetic also provides a simple and sometimes sharp method of bounding ranges of functions for global optimization and other tasks. Convenient use of interval arithmetic requires an interval data type in the programming language. Although various packages supply such a data type, previous ones are machine specific, obsolete, and unsupported, for languages other than Fortran, or commercial. The Fortran 90 module INTERVAL_ARITHMETIC provides a portable interval data type in Fortran 90. This data type is based on two double-precision real Fortran storage units. Module INTERVAL_ARTHMETIC uses the Fortran 77 library INTLIB (ACM TOMS Algorithm 737) as a supporting library. The module has been employed extensively in the author's own research.
Architectural potholes
Authors: Mark Rosenbaum
Venue: ACM SIGARCH Computer Architecture News (1996)

This column consists of selected traffic from the comp.arch newsgroup, a forum for discussion of computer architecture on Internet---an international computer network.
UC Berkeley's Digital Library project
Authors: Robert Wilensky
Venue: Communications of the ACM (1995)

For digital libraries to succeed, we must abandon the traditional notion of &ldquo;library&rdquo; altogether. The reason is as follows: The digital &ldquo;library&rdquo; will be a collection of distributed information services; producers of material will make it available, and consumers will find it and use it, perhaps through the help of automated agents. Libraries in the traditional sense are nowhere to be found in this model (i. e., the notion of a limited intermediary containing some small fraction of preselected material available only to local patrons is replaced by a system providing to users everywhere direct access to the full contents of all available material).
Achieving O(N) in simulating the billiards problem in discrete-event simulation
Authors: Gary Harless, Ralph V. Rogers
Venue: Proceedings of the 27th conference on Winter simulation (1995)

The paper identifies underlying issues associate with simulating those classes of problems which require both arbitrary spatial and temporal precision and which must deal the with the complexities of a multitude of asynchronous pair-wise interactions occuring among a dynamic non-uniform distribution of numerous spatial components. The principal issue of interest discussed focuses on a proposed simulation modeling methodology which dynamically sectors the trajectory space based on the number of spatial objects occupying a portion of the trajectory space (i.e. object space density). That is, the trajectory space is divided into sectors of various sizes such that each sector contains no more than some specified number of spatial components. The authors demonstrate that with such a dynamic sectoring methodology a theoretical reduction in the total number of pair-wise comparisons required during each time advancement can be achieved. Additionally, the theoretical computational complexity associated with identifying spatial conflicts will be better than O(N/sup 2/) for a non-uniform distribution of N spatial objects.
Fast text searching for regular expressions or automaton searching on tries
Authors: Ricardo A. Baeza-Yates, Gaston H. Gonnet
Venue: Journal of the ACM (JACM) (1996)

We present algorithms for efficient searching of regular expressions on preprocessed text, using a Patricia tree as a logical model for the index. We obtain searching algorithms that run in logarithmic expected time in the size of the text for a wide subclass of regular expressions, and in sublinear expected time for any regular expression. This is the first such algorithm to be found with this complexity.
Architecture validation for processors
Authors: Richard C. Ho, C. Han Yang, Mark A. Horowitz, David L. Dill
Venue: ACM SIGARCH Computer Architecture News (1995)

Modem, high performance microprocessors are extremely complex machines which require substantial validation effort to ensure functional correctness prior to tapeout. Generating the corner cases to test these designs is a mostly manual process, where completion is hard to judge. Experience shows that the errors that are caught late in the design, many post-silicon, are interactions between different components in very improbable corner case situations. In this paper we present a technique that targets such error-causing interactions by automatically generat- ing test vectors that will cause the processor to exercise all transitions of the control logic in simulation. We use techniques from formal verification to derive transition tours of a fully enumerated state graph of the control logic of the processor. Our system works from a Verilog description of the original machine and is currently being used to validate an embedded dual-issue processor in the node controller of the Stanford FLASH Multiprocessor. Modeling the processor control results in 200K states and an 8M instruction trace to check all transitions of control arcs.
Condition Estimation for Matrix Functions viathe Schur Decomposition
Authors: Roy Mathias
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

We show how to cheaply estimate the Frechet derivative and the condition number for a general class of matrix functions (the class includes the matrix sign function and functions that can be expressed as power series) via the Schur decomposition. In the case of the matrix sign function we also give a method to compute the Frechet derivative exactly. We also show that often this general method, based on the Schur decomposition, when applied the matrix sign function and the matrix exponential, enables one to compute the function and estimate its condition number more cheaply than the various special techniques that exploit special properties of these two functions.
Designing Clustered Multiprocessor Systems under Packaging and Technological Advancements
Authors: Debashis Basak, Dhabaleswar K. Panda
Venue: IEEE Transactions on Parallel and Distributed Systems (1996)

Clustered or hierarchical interconnections demonstrate advantage in designing large scale multiprocessor systems. Earlier studies in literature have either focused on only flat interconnections or proposed hierarchical/clustered interconnections with limited packaging and demanded performance constraints. Large systems require several levels of packaging. Packaging technologies impose various physical constraints on bisection bandwidth and channel width of a system. Pinout technologies and capacity of packaging modules have been ignored in earlier studies, often leading to configurations that are not design-feasible. Similarly, the impact of processor and interconnect technologies on demanded performance has also not been considered. In this paper, we propose a new supply-demand framework for multiprocessor system design by considering packaging, processor, and interconnect technologies in an integrated manner. The elegance of this framework lies in its parameterized representation of different technologies. For a given set of technological parameters the framework derives the best configuration while considering practical design aspects like maximum board area, maximum available pinout, fixed channel width, and scalability. In order to build a scalable parallel system with a given number of processors, the framework explores the design space of flat k-ary n-cube topologies and their clustered variations (k-ary n-cube cluster-c) to derive design-feasible configurations with best system performance. The study identifies processor board area, supported channel width, board pinout density, and router pinout as critical parameters and analyzes their impact on deriving design-feasible and best configurations. For a wide range of parameters, it is shown that best configurations are achieved with cluster-based systems with up to 8 processors per cluster and 3D-5D intercluster interconnection.
Learning Arithmetic Read-Once Formulas
Authors: Nader H. Bshouty, Thomas R. Hancock, Lisa Hellerstein
Venue: SIAM Journal on Computing (1995)

A formula is read-once if each variable appears at most once in it. An arithmetic read-once formula is one in which the operators are addition, subtraction, multiplication, and division. We present polynomial time algorithms for exact learning of arithmetic read-once formulas over a field. We present a membership and equivalence query algorithm that identifies arithmetic read-once formulas over an arbitrary field. We present a randomized membership query algorithm (i. e. a randomized black box interpolation algorithm) that identifies such formulas over finite fields with at least $2n+5$ elements (where $n$ is the number of variables), and over infinite fields. We also show the existence of non-uniform deterministic membership query algorithms for arbitrary read-once formulas over fields of characteristic 0, and for division-free read-once formulas over fields that have at least $2n^3+1$ elements. For our algorithms, we assume we are able to efficiently perform arithmetic operations on field elements and to compute square roots in the field. It is shown that the ability to compute square roots is necessary, in the sense that the problem of computing $n-1$ square roots in a field can be reduced to the problem of identifying an arithmetic formula over $n$ variables in that field. Our equivalence queries are of a slightly non-standard form, in which counterexamples are required not to be inputs on which the formula evaluates to $0/0$. This assumption is shown to be necessary for fields of size $o(n/\log {n})$, in the sense that we prove there exists no polynomial time identification algorithm that uses just membership and standard equivalence queries.
Representing representation: making a computer draw like a child: an MA computing in design research project
Authors: Ed Burton
Venue: ACM SIGGRAPH Computer Graphics (1995)

The study of children's drawing has shifted from the study of drawings as static artifacts to the study of drawing as a process. Here it is suggested that a process can be most suitably embodied in a medium appropriate to its active nature. This project uses computer programming as a medium to both represent and investigate a personal interpretation of children's drawing. The result is a computer application called Rose (Representation Of Spatial Experience). Inspired by the drawings of young children, Rose simulates the perception of the general shape and structure of three-dimensional computer models and constructs childlike two-dimensional representations of them.
How much AI does a cognitive science major need to know?
Authors: John Batali
Venue: ACM SIGART Bulletin (1995)

Artificial intelligence has given the world a set of programming tools and practices, a set of experiments and models, a set of experiences, and a set of intuitions about what intelligence, representation, and computation are about and are not about. What of this legacy is still relevant and crucial to a cognitive science undergraduate?
The partial-occlusion effect: utilizing semitransparency in 3D human-computer interaction
Authors: Shumin Zhai, William Buxton, Paul Milgram
Venue: ACM Transactions on Computer-Human Interaction (TOCHI) (1996)

This study investigates human performance when using semitransparent tools in interactive 3D computer graphics environments. The article briefly reviews techniques for presenting depth information and examples of applying semitransparency in computer interface design. We hypothesize that when the user moves a semitransparent surface in a 3D environment, the &ldquo;partial-occlusion&rdquo; effect introduced through semitransparency acts as an effective cue in target localization&mdash;an essential component in many 3D interaction tasks. This hypothesis was tested in an experiment in which subjects were asked to capture dynamic targets (virtual fish) with two versions of a 3D box cursor, one with and one without semitransparent surfaces. Results showed that the partial-occlusion effect through semitransparency significantly improved users' performance in terms of trial completion time, error rate, and error magnitude in both monoscopic and stereoscopic displays. Subjective evaluations supported the conclusions drawn from performance measures. The experimental results and their implications are discussed, with emphasis on the relative, discrete nature of the partial-occlusion effect and on interactions between different depth cues. The article concludes with proposals of a few future research issues and applications of semitransparency in human-computer interaction.
An overview of the new routing algorithm for the ARPANET
Authors: John M. McQuillan, Ira Richer, Eric C. Rosen
Venue: ACM SIGCOMM Computer Communication Review (1995)

The original routing algorithm of the ARPANET, in service for over a decade, has recently been removed from the ARPANET and replaced with a new and different algorithm. Although the new algorithm, like the old, is a distributed, adaptive routing algorithm, it is not similar to the old in any other important respect. In the new algorithm, each node maintains a data base describing the delay on each network line. A shortest-path computation is run in each node which explicitly computes the minimum-delay paths (based on the delay entries in the data base) from that node to all other nodes in the network. The average delay on each network line is measured periodically by the nodes attached to the lines. These measured delays are broadcast to all network nodes, so that all nodes use the same data base for performing their shortest-path computations. The new routing algorithm was extensively tested on the ARPANET before being released. This paper describes the algorithm and summarizes the results of these tests.
Mapping extended entity relationship model to object modeling technique
Authors: Joseph Fong
Venue: ACM SIGMOD Record (1995)

A methodology of reengineering existing extended Entity-Relationship(EER) model to Object Modeling Technique(OMT) model is described. A set of translation rules from EER model to a generic Object-Oriented(OO) model of OMT methodology is devised. Such reengineering practices not only can provide us with significant insight to the "interoperability" between the OO and the traditional semantic modelling techniques, but also can lead us to the development of a practical design methodology for object-oriented databases(OODB).
Real values of the W-function
Authors: D. A. Barry, P. J. Culligan-Hensley, S. J. Barry
Venue: ACM Transactions on Mathematical Software (TOMS) (1995)

Approximations for real values of W(x), where W is defined by solutions of W exp(W) = x, are presented. All of the approximations have maximum absolute (|W|>1) or relative (|W|<1) errors of O(10&minus;4). With these approximations an efficient algorithm, consisting of a single iteration of a rapidly converging iteration scheme, gives estimates of W(x) accurate to at least 16 significant digits (15 digits if double precision is used). The Fortran code resulting from the algorithm is written to account for the different floating-point-number mantissa lengths on different computers, so that W(x) is computed to the floating-point precision available on the host machine.
Finding $k$ Cuts within Twice the Optimal
Authors: Huzur Saran, Vijay V. Vazirani
Venue: SIAM Journal on Computing (1995)

Two simple approximation algorithms for the minimum $k$-cut problem are presented. Each algorithm finds a $k$ cut having weight within a factor of $(2-2/k)$ of the optimal. One of our algorithms is particularly efficient---it requires a total of only $n-1$ maximum flow computations for finding a set of near-optimal $k$ cuts, one for each value of $k$ between 2 and $n$.
CAD challenges in multimedia computing
Authors: Paul Lippens, Vijay Nagasamy, Wayne Wolf
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

Abstract: This tutorial surveys the present and future of multimedia computing systems and outlines new challenges for CAD presented by these systems. Multimedia computing is a challenging domain for several reasons: it requires both high computation rates and memory bandwidth; it is a multirate computing problem; and requires low-cost implementations for high-volume markets. As a result, the design of multimedia computing systems introduces new challenges for CAD at all levels of abstraction, ranging from layout to system design. After surveying the nature of the multimedia computing problem, we examine two experiences in multimedia computer design from a CAD perspective: the design of VLSI systems-on-chips for multimedia: and the successive refinement of an application from software to a high-volume chip using advanced CAD synthesis tools.
Fast pseudorandom generators for normal and exponential variates
Authors: C. S. Wallace
Venue: ACM Transactions on Mathematical Software (TOMS) (1996)

Fast algorithms for generating pseudorandom numbers from the unit-normal and unit-exponential distributions are described. The methods are unusual in that they do not rely on a source of uniform random numbers, but generate the target distributions directly by using their maximal-entropy properties. The algorithms are fast. The normal generator is faster than the commonly used Unix library uniform generator &ldquo;random&rdquo; when the latter is used to yield real values. Their statistical properties seem satisfactory, but only a limited suite of tests has been conducted. They are written in C and as written assume 32-bit integer arithmetic. The code is publicly available as C source and can easily be adopted for longer word lengths and/or vector processing.
ExpertFit: total support for simulation input modeling
Authors: Stephen Vincent, Averill M. Law
Venue: Proceedings of the 27th conference on Winter simulation (1995)

We explain the important role of simulation input modeling in a successful simulation study. Two pitfalls in simulation input modeling are then presented and we explain how any analyst, regardless of their knowledge of statistics, can easily avoid these pitfalls through the use of ExpertFit, the Windows based successor to the UniFit II input modeling package. We use a set of real world system data to demonstrate how the package automatically specifies, evaluates, and ranks candidate probability distributions, and then assists an analyst in deciding whether the "best" candidate probability distribution provides an adequate representation of the data. If no candidate probability distribution provides an adequate fit, then ExpertFit can define an empirical distribution function. In either case, the probability distribution can be automatically expressed in the analyst's simulation software. We then consider the general case of selecting a probability distribution in the absence of data. As an example, we show how ExpertFit can be used to create busy time and downtime models for machines that are subject to random breakdowns.
Algorithm 658: ODESSA–an ordinary differential equation solver with explicit simultaneous sensitivity analysis
Authors: Jorge R. Leis, Mark A. Kramer
Venue: ACM Transactions on Mathematical Software (TOMS) (1988)

ODESSA is a package of FORTRAN routines for simultaneous solution of ordinary differential equations and the associated first-order parametric sensitivity equations, yielding the ODE solution vector y&barbelow;(t) and the first-order sensitivity coefficients with respect to equation parameters p&barbelow;, &sgr;y&barbelow;(t)/&sgr;p&barbelow;. ODESSA is a modification of the widely disseminated initial-value solver LSODE, and retains many of the same operational features. Standard program usage and optional capabilities, installation, and verification considerations are addressed herein.