ppxscal/embedding_network huggingface dataset:
A case study of open source software development: the Apache server
Authors: Audris Mockus, Roy T. Fielding, James Herbsleb
Venue: Proceedings of the 22nd international conference on Software engineering (2000)

According to its proponents, open source style software development has the capacity to compete successfully, and perhaps in many cases displace, traditional commercial development methods. In order to begin investigating such claims, we examine the development process of a major open source application, the Apache web server. By using email archives of source code change history and problem reports we quantify aspects of developer participation, core team size, code ownership, productivity, defect density, and problem resolution interval for this OSS project. This analysis reveals a unique process, which performs well on important measures. We conclude that hybrid forms of development that borrow the most effective techniques from both the OSS and commercial worlds may lead to high performance software processes.
Using Decision Trees to Construct a Practical Parser
Authors: Masahiko Haruno, Satoshi Shirai, Yoshifumi Ooyama
Venue: Machine Learning (1999)

This paper describes a novel and practical Japanese parser that uses decision trees. First, we construct a single decision tree to estimate modification probabilities; how one phrase tends to modify another. Next, we introduce a boosting algorithm in which several decision trees are constructed and then combined for probability estimation. The constructed parsers are evaluated using the EDR Japanese annotated corpus. The single-tree method significantly outperforms the conventional Japanese stochastic methods. Moreover, the boosted version of the parser is shown to have great advantages&semi; (1) a better parsing accuracy than its single-tree counterpart for any amount of training data and (2) no over-fitting to data for various iterations. The presented parser, the first non-English stochastic parser with practical performance, should tighten the coupling between natural language processing and machine learning.
Generalized connection caching
Authors: Susanne Albers
Venue: Proceedings of the twelfth annual ACM symposium on Parallel algorithms and architectures (2000)

Cohen et al. [5] recently initiated the theoretical study of connection caching in the world-wide web. They extensively studied uniform connection caching, where the establishment cost is uniform for all connections [5, 6]. They showed that ordinary paging algorithms can be used to derive algorithms for uniform connection caching and analyzed various algorithms such as Belady's rule, LRU and Marking strategies. In particular, in [5] Cohen et al. showed that LRU yields a (2k - 1)-competitive algorithm, where k is the size of the largest cache in the network. In [6], they investigated Marking algorithms with different types of communication among nodes and presented deterministic k-competitive algorithms. In this paper we study generalized connection caching, also introduced in [5], where connections can incur varying establishment costs. This model is reasonable because the cost of establishing a connection may depend, for instance, on the distance of the nodes to be connected. We present optimal online algorithms for this generalized problem. Algorithms for ordinary weighted caching can be used to derive algorithms for generalized connection caching. We present tight or nearly tight analyses on the performance achieved by the currently known weighted caching algorithms when applied in generalized connection caching. The popular Balance algorithm yields a 2k-competitive algorithm. We prove that its competitive ratio is not smaller than (2k - 1). We then present implementations of the deterministic algorithm Landlord and the randomized algorithm Harmonic and show that they are k-competitive. This the best competitive ratio that can achieved by deterministic algorithms resp. by randomized algorithms against adaptive online adversaries. Additionally we consider two extensions of generalized connection caching where (1) connections have time-out values, or (2) the establishment cost of connections is asymmetric. We study the performance of Landlord and show that in the case of (1) it remains k-competitive. In the case of (2) we derive nearly tight upper and lower bounds.
Incremental Focus of Attention for Robust Vision-Based Tracking
Authors: Kentaro Toyama, Gregory D. Hager
Venue: International Journal of Computer Vision (1999)

We present the Incremental Focus of Attention (IFA) architecture for robust, adaptive, real-time motion tracking. IFA systems combine several visual search and vision-based tracking algorithms into a layered hierarchy. The architecture controls the transitions between layers and executes algorithms appropriate to the visual environment at hand: When conditions are good, tracking is accurate and precise&semi; as conditions deteriorate, more robust, yet less accurate algorithms take over&semi; when tracking is lost altogether, layers cooperate to perform a rapid search for the target and continue tracking.Implemented IFA systems are extremely robust to most common types of temporary visual disturbances. They resist minor visual perturbances and recover quickly after full occlusions, illumination changes, major distractions, and target disappearances. Analysis of the algorithm&lsquo;s recovery times are supported by simulation results and experiments on real data. In particular, examples show that recovery times after lost tracking depend primarily on the number of objects visually similar to the target in the field of view.
Resources, tools, and techniques for problem based learning in computing
Authors: Ainslie Ellis, Linda Carswell, Andrew Bernat, Daniel Deveaux, Patrice Frison, Veijo Meisalo, Jeanine Meyer, Urban Nulden, Joze Rugelj, Jorma Tarhio
Venue: ACM SIGCUE Outlook (1998)

In a problem-based learning (PBL) environment, students work in groups on real-life problems and have the opportunity to determine for themselves what they need to learn in the relevant subject area(s). A common feature of problem-based learning is to provide students with a range of resources that assist them in solving the problems. This paper attempts to classify resources according to the educational functions and activities for which they will be used. It also discusses communication patterns, assessment, and evaluation with respect to problem-based learning. Finally, it presents two case studies, one that illustrates a progression of problem development within the PBL environment and one that describes a practical application of PBL, with appropriate use of resources, for a first-year course in Java.
The emerging it group and rapid IT change
Authors: John “Skip” Benamati, Albert L. Lederer
Venue: Proceedings of the 2000 ACM SIGCPR conference on Computer personnel research (2000)

Information technology (IT) changes rapidly. This increases the complexity of IT management. In response, many organizations create a formal group of IT professionals to evaluate emerging IT and thus cope with its change. A survey based on structured interviews was mailed to a nationwide sample of 1,000 IT organizations. Two hundred forty-six respondents provided data to identify categories of coping mechanisms to handle changing IT. Five categories emerged, namely, Education and Training, Internal Procedures, Vendor Support, Consultant Support, and Endurance. Organizations with a group dedicated to investigating emerging IT cope more extensively (p < .01), but not more successfully than do those without one.
Memory forwarding: enabling aggressive layout optimizations by guaranteeing the safety of data relocation
Authors: Chi-Keung Luk, Todd C. Mowry
Venue: Proceedings of the 26th annual international symposium on Computer architecture (1999)

By optimizing data layout at run-time, we can potentially enhance the performance of caches by actively creating spatial locality, facilitating prefetching, and avoiding cache conflicts and false sharing. Unfortunately, it is extremely difficult to guarantee that such optimizations are safe in practice on today's machines, since accurately updating all pointers to an object requires perfect alias information, which is well beyond the scope of the compiler for languages such as C. To overcome this limitation, we propose a technique called memory forwarding which effectively adds a new layer of indirection within the memory system whenever necessary to guarantee that data relocation is always safe. Because actual forwarding rarely occurs (it exists as a safety net), the mechanism can be implemented as an exception in modern superscalar processors. Our experimental results demonstrate that the aggressive layout optimizations enabled by memory forwarding can result in significant speedups---more than twofold in some cases---by reducing the number of cache misses, improving the effectiveness of prefetching, and conserving memory bandwidth.
A Dedicated Multi-Chip Programmable System for Cellular Neural Networks
Authors: Mario Salerno, Fausto Sargeni, Vincenzo Bonaiuto
Venue: Analog Integrated Circuits and Signal Processing (1999)

Cellular Neural Networks (CNN&rsquo;s) represent a remarkable improvement in the hardware implementation of Artificial Neural Networks (ANN&rsquo;s). In fact, their regular structure and their local connectivity feature contribute to render this class of neural networks especially appealing for VLSI implementations. CNNs are widely applied in several fields, including image processing and pattern recognition. In this research, the authors already presented two fully digitally programmable CNN chips with 3&times;3 (3&times;3DPCNN chip) and 6&times;6 cells (6&times;6DPCNN chip) respectively. In this paper, a system with twenty of the latter chips will be presented. The main features of this electronic system consist of the full digital programmability of the templates, the digital input/output for logic operations, the analog outputs for dynamic analysis and the implementation of space-variant as well as space-invariant CNNs.
Hardware-only stream prefetching and dynamic access ordering
Authors: Chengqiang Zhang, Sally A. McKee
Venue: Proceedings of the 14th international conference on Supercomputing (2000)

Memory system bottlenecks limit performance for many applications, and computations with strided access patterns are among the hardest hit. The streams used in such applications have extremely poor cache behavior. These access patterns have the advantage of being predictable, though, and this can be exploited to improve the efficiency of the memory subsystem in two ways: memory latencies can be masked by prefetching stream data, and the latencies can be reduced by reordering stream accesses to exploit parallelism and locality within the DRAMs. Many researchers have studied hardware prefetching in its various forms. Others have examined dynamic memory scheduling to help bridge the performance gap between processors and DRAM memory systems. This study builds on these results, combining a stride-based reference prediction table, a mechanism that prefetches L2 cache lines, and a memory controller that dynamically schedules accesses to a Direct Rambus memory subsystem. We find that such a system delivers good speedups for scientific applications with regular access patterns without negatively affecting the performance of nonstreaming programs.
IP packet generation: statistical models for TCP start times based on connection-rate superposition
Authors: William S. Cleveland, Dong Lin, Don X. Sun
Venue: Proceedings of the 2000 ACM SIGMETRICS international conference on Measurement and modeling of computer systems (2000)

TCP start times for HTTP are nonstationary. The nonstationarity occurs because the start times on a link, a point process, are a superposition of source traffic point processes, and the statistics of superposition changes as the number of superposed processes changes. The start time rate is a measure of the number of traffic sources. The univariate distribution of the inter-arrival times is approximately Weibull, and as the rate increases, the Weibull shape parameter goes to 1, an exponential distribution. The autocorrelation of the log inter-arrival times is described by a simple, two-parameter process: white noise plus a long-range persistent time series. As the rate increases, the variance of the persistent series tends to zero, so the log times tend to white noise. A parsimonious statistical model for log inter-arrivals accounts for the autocorrelation, the Weibull distribution, and the nonstationarity in the two with the rate. The model, whose purpose is to provide stochastic input to a network simulator, has the desirable property that the superposition point process is generated as a single stream. The parameters of the model are functions of the rate, so to generate start times, only the rate is specified. As the rate increases, the model tends to a Poisson process. These results arise from theoretical and empirical study based on the concept of connection-rate superposition. The theory is the mathematics of superposed point processes, and the empiricism is an analysis of 23 million TCP connections organized into 10704 blocks of approximately 15 minutes each.
Risk-Sensitive Control of Finite State Machines on an Infinite Horizon II
Authors: Wendell H. Fleming, Daniel Hernández-Hernández
Venue: SIAM Journal on Control and Optimization (1999)

In this paper we present a sequel of Fleming and Hernandez-Hernandez, SIAM J. Control Optim., 35 (1997), pp. 1790--1810], extending those results to discrete time, output feedback (partial state information) systems. Our aim is to study both robust and risk-sensitive control of such systems on an infinite horizon. Appropriate information states are defined for each case, and dynamic programming results are obtained.
17,500 software patents to issue in 1998
Authors: Greg Aharonian
Venue: ACM SIGSOFT Software Engineering Notes (1999)

Based on an analysis of 3336 software patents issued circa January/August of 1998, I have put together the following statistics. Simply put, in 1998 and 1999 the PTO will issue 40,000 software patents, ten times the amount issued six years earlier in 1992 and 1993, without ten times the resources.
The DataIndex: a structure for smaller, faster data warehouses
Authors: Anindya Datta, Igor Viguier
Venue: ACM SIGMIS Database (1998)

In this paper we present DataIndexes, a family of design strategies for data warehouses to support OnLine Analytical Processing (OLAP). As the name implies, DataIndexes are both a storage structure for the warehoused relational data and an indexing scheme to provide fast access to that data. We present two simple DataIndexes: the Basic DataIndex (BDI), which can be used for any attribute and the Join DataIndex (JDI), which is used for foreign-key attributes. Either structure can be shown to significantly improve query response times in most cases. And, since they serve as indexes as well as the store of base data, DataIndexes actually define a physical design strategy for a data warehouse where the indexing, for all intents and purposes, comes for "free."
Measures of complexity for cancellous bone
Authors: Wolfgang Gowin, Peter I. Saparin, Jürgen Kurths, Dieter Felsenberg
Venue: Technology and Health Care (1998)

The problem of quantifying the structure of cancellous bone has been addressed in the past by histomorphometry and more recently by imaging techniques using X-ray attenuation. The current approaches compute and describe parts of the construction of the trabecular net. We developed a new technique which quantifies cancellous bone of human lumbar vertebrae as a whole. The interactions, transactions, and interrelationships of all parts of the structural composition of the trabeculae are accounted for and quantified. The method is based on the concept of structural complexity within the framework of nonlinear dynamics. The methodology was developed by using axial high resolution computed tomography images. The technique was transferred to quantitative computed tomography images and is based on the non-invasive assessment of 50 human L3 specimens. The value of Houndsfield units per pixel representing trabecular bone of the vertebrae was transformed into color-encoded and alphabet-encoded symbols. The procedure of transformation of the X-ray attenuation pixels into symbols was necessary as a basis on which measures of complexity were introduced to assess the composition of symbols within the images. The development of a generalization of symbolic dynamics, a mathematical method, to work with two-dimensional images was a prerequisite. The results of this study demonstrate that the structural composition of cancellous bone declines more rapidly than bone mineral density during the loss of bone. This outcome strongly suggests an exponential relationship between bone mineral density and the architectural composition of cancellous bone. Normal trabecular bone has a complex ordered structure. The structural composition during the osteopenic phase of bone loss is characterized by lower structural complexity and a significantly higher level of architectural disorder. A high grade of osteoporosis leads again to an ordered structure, although its structural complexity is minimal.
Block Pseudospectral Methods for Maxwell's Equations II: Two-Dimensional, Discontinuous-Coefficient Case
Authors: Tobin A. Driscoll, Bengt Fornberg
Venue: SIAM Journal on Scientific Computing (1999)

Block pseudospectral (BPS) methods are examined for Maxwell's equations in two-dimensional inhomogeneous media. For the case of a rectangular strip with a straight-line interface, blocks may be coupled via fictitious points or a generalization of characteristic outflow conditions. The BPS methods generalize to curvilinear strips described by a change of variables. Such strips can conform to interfaces while overlapping with a high-order free-space grid to form a composite grid method. Numerical experiments on strips with dielectrics, lossy materials, perfect conductors, and absorbing layers indicate that the two coupling methods are comparable and accurate with just 3--4 points per wavelength. Full composite examples are included to demonstrate high accuracy and geometric flexibility.
An Efficient Newton-Type Iteration for the Numerical Solution of Highly Oscillatory Constrained Multibody Dynamic Systems
Authors: Jeng Yen, Linda R. Petzold
Venue: SIAM Journal on Scientific Computing (1998)

In this paper we present a coordinate-split (CS) technique for the numerical solution of the equations of motion of constrained multibody dynamic systems. We show how the CS technique can be implemented within the context of commonly used solution methods, for increased efficiency and reliability.A particularly challenging problem for multibody dynamics is the numerical solution of highly oscillatory nonlinear mechanical systems. Highly stable implicit integration methods with large stepsizes can be used to damp the oscillation, if it is of small amplitude. However, the standard Newton iteration is known to experience severe convergence difficulties which force a restriction of the stepsize. We introduce a modified coordinate-split (CM) iteration which overcomes these problems. Convergence analysis explains the improved convergence for nonlinear oscillatory systems, and numerical experiments illustrate the effectiveness of the new method.
Monitoring QoS distribution in multimedia networks
Authors: Chen-Khong Tham Yuming Jiang
Venue: International Journal of Network Management (2000)

This paper presents two schemes, relevant monitor &lpar;RM&rpar;-based and improved relevant monitor &lpar;IRM&rpar;-based, for QoS distribution monitoring. With these schemes, when monitoring a real-time flow, a network manager can locate relevant monitors that are metering the flow. Copyright &copy; 2000 John Wiley Sons, Ltd.
The Future Fast Fourier Transform?
Authors: Alan Edelman, Peter McCorquodale, Sivan Toledo
Venue: SIAM Journal on Scientific Computing (1999)

It seems likely that improvements in arithmetic speed will continue to outpace advances in communication bandwidth. Furthermore, as more and more problems are working on huge datasets, it is becoming increasingly likely that data will be distributed across many processors because one processor does not have sufficient storage capacity. For these reasons, we propose that an inexact DFT such as an approximate matrix-vector approach based on singular values or a variation of the Dutt--Rokhlin fast-multipole-based algorithm may outperform any exact parallel FFT. The speedup may be as large as a factor of three in situations where FFT run time is dominated by communication. For the multipole idea we further propose that a method of "virtual charges" may improve accuracy, and we provide an analysis of the singular values that are needed for the approximate matrix-vector approaches.
Effective and Efficient Knowledge Base Refinement
Authors: Leonardo Carbonara, Derek Sleeman
Venue: Machine Learning (1999)

This paper presents the STALKER knowledge base refinement system. Like its predecessor KRUST, STALKER proposes many alternative refinements to correct the classification of each wrongly classified example in the training set. However, there are two principal differences between KRUST and STALKER. Firstly, the range of misclassified examples handled by KRUST has been augmented by the introduction of inductive refinement operators. Secondly, STALKER&lsquo;s testing phase has been greatly speeded up by using a Truth Maintenance System (TMS). The resulting system is more effective than other refinement systems because it generates many alternative refinements. At the same time, STALKER is very efficient since KRUST&lsquo;s computationally expensive implementation and testing of refined knowledge bases has been replaced by a TMS-based simulator.