ppxscal/embedding_network huggingface dataset:
Distributional Word Problem for Groups
Authors: Jie Wang
Venue: SIAM Journal on Computing (1999)

This paper studies the word problem for finitely presented groups under the restriction that words can only be rewritten for a bounded number of times. We obtain a similar result to the Novikov--Boone theorem in the setting of average-case NP-completeness. The word problem we consider here is to decide, when given a finite presentation of a group G, words x, y, z, and an integer k, whether (x-1yx)z can be derived from z(x-1yx)z in the presentation of G in k steps. We show that when each component of the instance is chosen uniformly at random, the problem cannot be solved fast on average unless every NP problem under every reasonable distribution on instances can be solved fast on average.
&ldquo;Honey, I shrunk the database&rdquo;: footprint, mobility, and beyond
Authors: Praveen Seshadri
Venue: ACM SIGMOD Record (1999)

The small-scale mobile computing market (palmtops, handhelds, smartphones, smartcards, etc.) is showing the most explosive growth in the history of computing. Within the last year, most database vendors have announced plans to build &ldquo;small footprint&rdquo; versions of their DBMS products to run on these small and mobile platforms. What are the real database systems issues? What are the likely markets? What are the challenges, and the dangers? Every specific vendor seems to have a different answer to these questions. They all agree on only one thing: there is a tremendous opportunity here. Our motivation for this panel is to get a number of the central decision-makers into a room and debate the issues.
Towards self-tuning data placement in parallel database systems
Authors: Mong Li Lee, Masaru Kitsuregawa, Beng Chin Ooi, Kian-Lee Tan, Anirban Mondal
Venue: ACM SIGMOD Record (2000)

Parallel database systems are increasingly being deployed to support the performance demands of end-users. While declustering data across multiple nodes facilitates parallelism, initial data placement may not be optimal due to skewed workloads and changing access patterns. To prevent performance degradation, the placement of data must be reorganized, and this must be done on-line to minimize disruption to the system. In this paper, we consider a dynamic self-tuning approach to reorganization in a shared nothing system. We introduce a new index-based method that faciliates fast and efficient migration of data. Our solution incorporates a globally height-balanced structure and load tracking at different levels of granularity. We conducted an extensive performance study, and implemented the methods on the Fujitsu AP3000 machine. Both the simulation and empirical results demonstratic that our proposed method is indeed scalable and effective in correcting any deterioration in system throughput.
An industry analysis of developer beliefs about object-oriented systems development
Authors: Richard A. Johnson, Bill C. Hardgrave, E. Reed Doke
Venue: ACM SIGMIS Database (1999)

Object-oriented systems development (OOSD) is a recent innovation in software development that is often cited as a viable solution to many of the ills plaguing this critical industry. However, some express doubt about the potentially over-hyped claims of OOSD. While there are many accounts of the successful application of OOSD, widespread acceptance has not been achieved, implying that OOSD may not be viewed as positively by industry as the literature would suggest.To address this dilemma, the present study examines a wide variety of specific beliefs about OOSD as provided by a survey of 150 systems developers. Using Ajzen's (1988) theory of planned behavior as a foundation, an exploratory factor analysis is performed to determine which specific beliefs about OOSD are indeed salient indicators of three fundamental concepts that should influence acceptance: the usefulness of OOSD, social pressure to use OOSD, and the ease of using OOSD. The results of the study reveal that while many specific beliefs about OOSD are indeed salient indicators of these more fundamental, potentially influential factors, many other beliefs are not. This study should prove helpful to practitioners who are considering the adoption or continued use of OOSD, and to researchers who are interested in the diffusion of innovations in general
Likelihood Ratio Derivative Estimation for Finite-Time Performance Measures in Generalized Semi-Markov Processes
Authors: Marvin K. Nakayama, Perwez Shahabuddin
Venue: Management Science (1998)

This paper investigates the likelihood ratio method for estimating derivatives of finite-time performance measures in generalized semi-Markov processes (GSMPs). We develop readily verifiable conditions for the applicability of this method. Our conditions mainly place restrictions on the basic building blocks (i.e., the transition probabilities, the distribution and density functions of the event lifetimes, and the initial distribution) of the GSMP, which is in contrast to the structural conditions needed for infinitesimal perturbation analysis. We explicitly show that our conditions hold in many practical settings, and in particular, for large classes of queueing and reliability models. One intermediate result we obtain in this study, which is of independent value, is to formally show that the random variable representing the number of occurring events in a GSMP in a finite time horizon, has finite exponential moments in a neighborhood of zero.
Decidability of bisimulation equivalence for normed pushdown processes
Authors: Colin Stirling
Venue: ACM SIGACT News (1999)

As a service to our readers, SIGACT News has an agreement with Computing Reviews to reprint reviews of books and articles of interest to the theoretical computer science community. Computing Reviews is a monthly journal that publishes critical reviews on a broad range of computing subjects, including models of computation, formal languages, computational complexity theory, analysis of algorithms, and logics and semantics of programs. ACM members can receive a subscription to Computing Reviews for $45 per year by writing to ACM headquarters.
Validation of an Approach for Improving Existing Measurement Frameworks
Authors: Manoel G. Mendonça, Victor R. Basili
Venue: IEEE Transactions on Software Engineering (2000)

Software organizations are in need of methods to understand, structure, and improve the data they are collecting. We have developed an approach for use when a large number of diverse metrics are already being collected by a software organization [1], [2]. The approach combines two methods. One looks at an organization's measurement framework in a top-down goal-oriented fashion and the other looks at it in a bottom-up data-driven fashion. The top-down method is based on a measurement paradigm called Goal-Question-Metric (GQM). The bottom-up method is based on a data mining technique called Attribute Focusing (AF). A case study was executed to validate this approach and to assess its usefulness in an industrial environment. The top-down and bottom-up methods were applied in the customer satisfaction measurement framework at the IBM Toronto Laboratory. The top-down method was applied to improve the customer satisfaction (CUSTSAT) measurement from the point of view of three data user groups. It identified several new metrics for the interviewed groups, and also contributed to better understanding the data user needs. The bottom-up method was used to gain new insights into the existing CUSTSAT data. Unexpected associations between key variables prompted new business insights, and revealed problems with the process used to collect and analyze the CUSTSAT data. This paper uses the case study and its results to qualitatively compare our approach against current ad hoc practices used to improve existing measurement frameworks.
A Family of Regularizing Kernels for Averaging in the Presence of Template Jitter
Authors: Hemant D. Tagare
Venue: Journal of Mathematical Imaging and Vision (1999)

While computing the regularized mean in medical image analysis, compensation for anatomical variation between different subjects is achieved by registering data with a standard template. In practice, template registration is never perfect and registration error (called jitter) can influence any statistic that is calculated using the template. This paper considers the design of regularizing filters which makes the effect of jitter harmless on the computed mean. The design is based on a new notion called jitter-resistant filtering. A regularizing kernel is jitter resistant if the effect of jitter on the regularized data is similar to a slight change in the scale of the kernel in the absence of jitter. Based on this notion, it is shown that the family of Gaussian filters is a jitter-resistant family of regularizing filters. Simulations in support of the theory are also presented.
Robust Convex Optimization
Authors: A. Ben-Tal, A. Nemirovski
Venue: Mathematics of Operations Research (1998)

We study convex optimization problems for which the data is not specified exactly and it is only known to belong to a given uncertainty set U, yet the constraints must hold for all possible values of the data from U. The ensuing optimization problem is called robust optimization. In this paper we lay the foundation of robust convex optimization. In the main part of the paper we show that if U is an ellipsoidal uncertainty set, then for some of the most important generic convex optimization problems (linear programming, quadratically constrained programming, semidefinite programming and others) the corresponding robust convex program is either exactly, or approximately, a tractable problem which lends itself to efficientalgorithms such as polynomial time interior point methods.
A Pseudorandom Generator from any One-way Function
Authors: Johan HÅstad, Russell Impagliazzo, Leonid A. Levin, Michael Luby
Venue: SIAM Journal on Computing (1999)

Pseudorandom generators are fundamental to many theoretical and applied aspects of computing. We show how to construct a pseudorandom generator from any one-way function. Since it is easy to construct a one-way function from a pseudorandom generator, this result shows that there is a pseudorandom generator if and only if there is a one-way function.
Classroom Note: Calculation of Weights in Finite Difference Formulas
Authors: Bengt Fornberg
Venue: SIAM Review (1998)

The classical techniques for determining weights in finite difference formulas were either computationally slow or very limited in their scope (e.g., specialized recursions for centered and staggered approximations, for Adams--Bashforth-, Adams--Moulton-, and BDF-formulas for ODEs, etc.). Two recent algorithms overcome these problems. For equispaced grids, such weights can be found very conveniently with a two-line algorithm when using a symbolic language such as Mathematica (reducing to one line in the case of explicit approximations). For arbitrarily spaced grids, we describe a computationally very inexpensive numerical algorithm.
Kronecker Stratification of the Space of Quadruples of Matrices
Venue: SIAM Journal on Matrix Analysis and Applications (1998)

In this paper, we study the partition of the space of quadruples of matrices according to the set of discrete structural invariants, proving that it is a stratification and that the structural stability under this equivalence relation is a generic property in the space of quadruples of matrices.We give an application to obtain bifurcation diagrams for some few-parameters families of quadruples of matrices.
Distance-Regular Graphs of Valency 6 and a1 = 1
Authors: Akira Hiraki, Kazumasa Nomura, Hiroshi Suzuki
Venue: Journal of Algebraic Combinatorics: An International Journal (2000)

We give a complete classification of distance-regular graphs of valency 6 and a_1 &equals; 1.
Exploiting temporal uncertainty in parallel and distributed simulations
Authors: Richard M. Fujimoto
Venue: Proceedings of the thirteenth workshop on Parallel and distributed simulation (1999)

Parallel discrete event simulation algorithms are usually based on time stamp ordering of events. Distributed virtual environment (DVE) applications such as DIS typically use unordered event delivery. A partial order called approximate time (AT) is proposed to order events in both domains, facilitating reuse of simulations across DVE and analysis applications. A variation on AT-order called approximate time causal (ATC) order is also described. Synchronization algorithms to realize these orderings are presented as well as performance measurements on a workstation cluster. A long-term goal of this work is to use AT and ATC order to exploit temporal uncertainty in the model to achieve efficient conservative parallel simulation despite little or no lookahead, a longstanding problem in the field.
Laboratory experiment with the 3RolesPlaying method
Authors: Anna Bobkowska
Venue: ACM SIGCSE Bulletin (1999)

The paper addresses the problem of making experiments for software engineering during laboratories. There is a need for experimental investigations. If experiments are performed in the lab together with training they must also have high educational value. In the paper, there is discussion about joining education and research. Then summary of the 3RolesPlaying method which satisfies goals of both of them is presented. Results of an experiment that took place in the Technical University of Gdansk, Poland in the summer semester of 1997/98 are described, and verification of the results value is made.
Sensory feedback in artificial control of human mobility
Authors: Peter H. Veltink
Venue: Technology and Health Care (1999)

Artificial motor control systems may reduce the handicap of motor impaired individuals. Sensors are essential components in feedback control of these systems and in the information exchange with the user. The objective of this paper is to give an overview of the applications of sensors in the artificial control of human mobility. These applications may either require an accurate estimate of the measured physical quantities or can be based on learning the relation between sensory information and control actions by example. Actual use of sensors in artificial motor control systems requires that the user experienced complexity of the system is not increased, while improving the repeatable and flexible functioning of the system. Therefore, the sensors need to be integrated with the mechanical part of the artificial support system or implanted, the information exchange between sensor and controller should be wireless and automatic in-use calibration is a desired feature.
Silhouette clipping
Authors: Pedro V. Sander, Xianfeng Gu, Steven J. Gortler, Hugues Hoppe, John Snyder
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

Approximating detailed with coarse, texture-mapped meshes results in polygonal silhouettes. To eliminate this artifact, we introduce silhouette clipping, a framework for efficiently clipping the rendering of coarse geometry to the exact silhouette of the original model. The coarse mesh is obtained using progressive hulls, a novel representation with the nesting property required for proper clipping. We describe an improved technique for constructing texture and normal maps over this coarse mesh. Given a perspective view, silhouettes are efficiently extracted from the original mesh using a precomputed search tree. Within the tree, hierarchical culling is achieved using pairs of anchored cones. The extracted silhouette edges are used to set the hardware stencil buffer and alpha buffer, which in turn clip and antialias the rendered coarse geometry. Results demonstrate that silhouette clipping can produce renderings of similar quality to high-resolution meshes in less rendering time.
Rewriting of rules containing set terms in a logic data language LDL
Authors: Oded Shmueli, Shalom Tsur, Carlo Zaniolo
Venue: Proceedings of the seventh ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1988)

We propose compilation methods for supporting set terms in Horn clause programs, without using general-purpose set matching algorithms, which tend to run in times exponential in the size of the participating sets Instead, we take the approach of formulating specialized computation plans that, by taking advantage of information available in the given rules, limit the number of alternatives explored. Our strategy is to employ compile time rewriting techniques and to transform the problem into an &ldquo;ordinary&rdquo; Horn clause compilation problem, with minimal additional overhead. The execution cost of the rewritten rules is substantially lower than that of the original rules and the additional cost of compilation can thus be amortized over many executions
A New Decoding Algorithm for Complete Decoding of Linear Block Codes
Authors: Yunghsiang S. Han
Venue: SIAM Journal on Discrete Mathematics (1998)

In this paper we present and describe an improved version of the Zero-Neighbors algorithm, which we call the Zero-Coverings algorithm. We also present a method for finding a smallest subset of codewords ( Zero-Coverings) which need to be stored to perform the Zero-Coverings algorithm. For some short codes, the sizes of Zero-Coverings are obtained by computer searches; for long codes, an asymptotic bound on the sizes of such subsets is also given.
Seamless texture mapping of subdivision surfaces by model pelting and texture blending
Authors: Dan Piponi, George Borshukov
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

Subdivision surfaces solve numerous problems related to the geometry of character and animation models. However, unlike on parametrised surfaces there is no natural choice of texture coordinates on subdivision surfaces. Existing algorithms for generating texture coordinates on non-parametrised surfaces often find solutions that are locally acceptable but globally are unsuitable for use by artists wishing to paint textures. In addition, for topological reasons there is not necessarily any choice of assignment of texture coordinates to control points that can satisfactorily be interpolated over the entire surface. We introduce a technique, pelting, for finding both optimal and intuitive texture mapping over almost all of an entire subdivision surface and then show how to combine multiple texture mappings together to produce a seamless result.
Computing the Kantorovich Distance for Images
Authors: Thomas Kaijser
Venue: Journal of Mathematical Imaging and Vision (1998)

Computing the Kantorovich distance for images is equivalent to solving a very large transportation problem. The cost-function of this transportation problem depends on which distance-function one uses to measure distances between pixels.In this paper we present an algorithm, with a computational complexity of roughly order {\cal O}(N2), where N is equal to the number of pixels in the two images, in case the underlying distance-function is the L1-metric, an approximation of the L2-metric or the square of the L2-metric; a standard algorithm would have a computational complexity of order {\cal O} (N3). The algorithm is based on the classical primal-dual algorithm.The algorithm also gives rise to a transportation plan from one image to the other and we also show how this transportation plan can be used for interpolation and possibly also for compression and discrimination.
XML and electronic commerce: enabling the network economy
Authors: Bart Meltzer, Robert Glushko
Venue: ACM SIGMOD Record (1998)

There has been a lot of talk about how the Internet is going to change the world economy. Companies will come together in a &ldquo;plug and play&rdquo; fashion to form trading partner networks. Virtual companies will be established and new business models can be created based on access to information and agents that can carry it around the world using computer networks.
Algorithm simulation with automatic assessment
Authors: Ari Korhonen, Lauri Malmi
Venue: Proceedings of the 5th annual SIGCSE/SIGCUE ITiCSEconference on Innovation and technology in computer science education (2000)

Visualization is a useful aid for understanding the working of algorithms. Therefore many interactive algorithm animation tools have been developed. However, students may misinterpret the visualization and therefore the correctness of their interpretation should be confirmed by tests supplemented with feedback.In this paper, a learning environment for data structures and algorithms is presented. The combination of algorithm animation and simulation with automatic assessment provides a way to give meaningful feedback to the students. Our experience shows that this combination is of great value for the students studying algorithms.
Understanding Why Correlation Profiling Improves the Predictability of Data Cache Misses in Nonnumeric Applications
Authors: Todd C. Mowry, Chi-Keung Luk
Venue: IEEE Transactions on Computers (2000)

Latency-tolerance techniques offer the potential for bridging the ever-increasing speed gap between the memory subsystem and today's high-performance processors. However, to fully exploit the benefit of these techniques, one must be careful to apply them only to the dynamic references that are likely to suffer cache misses¿otherwise the runtime overheads can potentially offset any gains. In this paper, we focus on isolating dynamic miss instances in nonnumeric applications, which is a difficult but important problem. Although compilers cannot statically analyze data locality in nonnumeric applications, one viable approach is to use profiling information to measure the actual miss behavior. Unfortunately, the state-of-the-art in cache miss profiling (which we call summary profiling) is inadequate for references with intermediate miss ratios¿it either misses opportunities to hide latency, or else inserts overhead that is unnecessary. To overcome this problem, we propose and evaluate a new profiling technique that helps predict which dynamic instances of a static memory reference will hit or miss in the cache: correlation profiling. Our experimental results demonstrate that roughly half of the 21 nonnumeric applications we study can potentially enjoy significant reductions in memory stall time by exploiting at least one of the three forms of correlation profiling we consider: control-flow correlation, self correlation, and global correlation. In addition, our detailed case studies illustrate that self correlation succeeds because a given reference's cache outcomes often contain repeated patterns and control-flow correlation succeeds because cache outcomes are often call-chain dependent. Finally, we suggest a number of ways to exploit correlation profiling in practice and demonstrate that software prefetching can achieve better performance on a modern superscalar processor when directed by correlation profiling rather than summary profiling information.
MA-WATM: a new approach towards an adaptive wireless ATM network
Authors: Khaldoun Al agha, Houda Labiod
Venue: Mobile Networks and Applications (1999)

In a cellular multimedia network like wireless ATM (WATM), self control seems primordial. Our new approach is based on the application of DAI (distributed artificial intelligence) techniques in order to build a self-adaptive network within random non-uniform traffic conditions. Attempting to achieve a high network capacity in terms of resource allocation and air interface BER (bit error rate), we propose to apply intelligent agent features to enhance the architecture of WATM systems. In fact, the intelligent platform MA-WATM (multi-agent wireless ATM) is used to provide a flexible integration of the multi-agent technique in wireless entities, BSs (base stations), MSs (mobile stations) and MSCs (mobile switching centers). Two applications are investigated and explored by simulations in order to bear out the feasibility of the multi-agent approach.