ppxscal/embedding_network huggingface dataset:
The complexity of deciding stability under FFS in the adversarial queueing model
Authors: C. Àlvarez, M. Blesa, J. Díaz, A. Fernández, M. Serna
Venue: Information Processing Letters (2004)

We address the problem of deciding whether a given network is stable in the Adversarial Queueing Model when considering farthest-from-source (FFS) as the queueing policy to schedule the packets through its links. We show a characterisation of the networks which are stable under FFS in terms of a family of forbidden subgraphs. We show that the set of networks stable under FFS coincide with the set of universally stable networks. Since universal stability of networks can be checked in polynomial time, we obtain that stability under FFS can also be decided in polynomial time.
A finite element method for unstructured grid smoothing
Authors: Glen Hansen, Andrew Zardecki, Doran Greening, Randy Bos
Venue: Journal of Computational Physics (2004)

The finite element method is applied to grid smoothing for two-dimensional planar geometry. The coordinates of the grid nodes satisfy two quasi-linear elliptic equations in the form of Laplace equations in a Riemann space. By forming a Dirichlet boundary value problem, the proposed method is applicable to both structured and unstructured grids. The Riemannian metric, acting as a driving force in the grid smoothing, is computed iteratively beginning with the metric of the unsmoothed grid. Smoothing is achieved by computing the metric tensor on the dual mesh elements, which incorporates the influence of neighbor elements. Numerical examples of this smoothing methodology, demonstrating the efficiency of the proposed approach, are presented.
Regional Observability for Semilinear Distributed Parabolic Systems
Authors: E. Zerrik, H. Bourray, A. El Jai
Venue: Journal of Dynamical and Control Systems (2004)

The purpose of this paper is to explore the concept of regional observability for a class of semilinear distributed parabolic systems. Then we give an approach for the reconstruction of the state on a subregion of the evolution domain. We also study the variation of the estimated state error with respect to measurements errors. At last we present an approach based on fixed point techniques leading to a numerical approach which is successfully tested through an example.
Effects of exercise breaks on performance, muscular load, and perceived discomfort in data entry and cognitive tasks
Authors: Rana Balci, Fereydoun Aghazadeh
Venue: Computers and Industrial Engineering (2004)

An effective work-rest schedule is an economical way to potentially reduce physical and psychological problems associated with computer usage. In this study, three different work-rest schedules were investigated: 60-min work/10-min rest, 30-min work/5-min rest, and for the third schedule (15/micro), the participants received four breaks from each hour in addition to a 14-min break after 2 h (three of these breaks were 30 s in length and the fourth break was 3 min in length). The study also considered the effect of the type of task. Participants were asked to enter alphanumeric data as a data entry task and to solve addition/subtraction problems as a cognitive task.The results indicated that the effect of work-rest schedule was significant on various perceived discomfort categories and the performance of the subjects. Similarly, the type of task had significant effects on discomfort, performance, and muscular load levels. The 15/micro schedule was superior to the other schedules in terms of discomfort levels of the neck, back, and elbow/arm, eyestrain, speed, accuracy, and performance for both tasks. The lowest levels of trapezius muscle tension for data entry and flexor carpi radialis (FCR) for cognitive tasks obtained with the 15/micro schedule. The cognitive task resulted in a higher psychological discomfort (nervousness, tiredness, dizziness, and headache), but lower physical discomfort and performance than the data entry task. The results of the study suggest that the 15/micro schedule is preferable to the longer and infrequent rest break schedules considering upper extremity discomfort, eyestrain, speed, accuracy, and performance of participants.
Duration-constrained regular expressions
Authors: Li Xuandong, Zhao Jianhua, Zheng Tao, Li Yong, Zheng Guoliang
Venue: Formal Aspects of Computing (2004)

This paper investigates the logic-automata-connection for Duration Calculus. It has been frequently observed that Duration Calculus with linear duration terms comes close to being a logic of linear hybrid automata. We attempt to make this relation precise by constructing Kleene-connection between duration-constrained regular expressions and a subclass of linear hybrid automata called loop-reset automata in which any variable tested in a loop is reset in the same loop. The formalism of duration-constrained regular expressions is an extension of regular expressions with duration constraints, which are essentially formulas of Duration Calculus without negation, yet extended by a Kleene-star operator. In this paper, we show that this formalism is equivalent in expressive power to loop-reset automata by providing a translation procedure from expressions to automata and vice verse.
Online maintenance of very large random samples
Authors: Christopher Jermaine, Abhijit Pol, Subramanian Arumugam
Venue: Proceedings of the 2004 ACM SIGMOD international conference on Management of data (2004)

Random sampling is one of the most fundamental data management tools available. However, most current research involving sampling considers the problem of how to use a sample, and not how to compute one. The implicit assumption is that a "sample" is a small data structure that is easily maintained as new data are encountered, even though simple statistical arguments demonstrate that very large samples of gigabytes or terabytes in size can be necessary to provide high accuracy. No existing work tackles the problem of maintaining very large, disk-based samples from a data management perspective, and no techniques now exist for maintaining very large samples in an online manner from streaming data. In this paper, we present online algorithms for maintaining on-disk samples that are gigabytes or terabytes in size. The algorithms are designed for streaming data, or for any environment where a large sample must be maintained online in a single pass through a data set. The algorithms meet the strict requirement that the sample always be a true, statistically random sample (without replacement) of all of the data processed thus far. Our algorithms are also suitable for biased or unequal probability sampling.
Signaling contours by neuromorphic wave propagation
Authors: Christoph Rasche
Venue: Biological Cybernetics (2004)

We describe a neuromorphic retina that signals a luminance edge as a spike. In a fast process, the luminance profile of the receptor layer determines the membrane potential of the ganglion cells and their individual, adjustable spiking thresholds. In a slower process, a wave-propagation process, the charge of ganglion cells with high membrane potential will propagate toward neighboring cells with low membrane potential and low spiking threshold, thus signaling the edge as a spike. Following that, the signaled edge (or contour) actively propagates across the retinal map. The retinal signal can be used for a contour-integration or a contour-propagation approach.
Sharp estimates for triangular sets
Authors: Xavier Dahan, Éric Schost
Venue: Proceedings of the 2004 international symposium on Symbolic and algebraic computation (2004)

We study the triangular representation of zero-dimensional varieties defined over the rational field (resp. a rational function field). We prove polynomial bounds in terms of intrinsic quantities for the height (resp. degree) of the coefficients of such triangular sets, whereas previous bounds were exponential. We also introduce a rational form of triangular representation, for which our estimates become linear. Experiments show the practical interest of this new representation.
A. Genetic Algorithm for Inferring Time Delays in Gene Regulatory Networks
Authors: Fang-Xiang Wu, Anthony J. Kusalik, Wen-Jun Zhang
Venue: Proceedings of the 2004 IEEE Computational Systems Bioinformatics Conference (2004)

Recently we proposed a state-space model with time delays for gene regulatory networks. Although the system can be uniquely determined under some assumptions, the solution space is still too large to use an exhaustive search method to find the optimal solution. This work employs Boolean variables to capture the existence of the discrete time delays of the regulatory relationships among the internal variables, and proposes a genetic algorithm (GA) to determine the optimal Boolean variables (the optimal solution) and to further infer gene regulatory networks with time delays. Computational experiments performed on a real gene expression dataset show that GA is effective at finding the optimal solution. Not only does the regulatory network with time delay obtained from the dataset possesses the expected properties of a real one, but the approach also improves the prediction accuracy by 72%, compared to gene regulatory network without time delays.
Improving Requirements Management in Extreme Programming with Tool Support - An Improvement Attempt that Failed
Authors: Jukka Kaariainen, Juha Koskela, Pekka Abrahamsson, Juha Takalo
Venue: Proceedings of the 30th EUROMICRO Conference (2004)

While Extreme programming (XP) relies on certain principles, it requires an extensive set of tools to enable an effective execution of its practices. In many companies, putting stories on the board may not be sufficient for managing rapidly changing requirements. The objective of this paper is to report the results from a study where a requirement management tool - the Storymanager - was developed to meet the needs of a XP project team. The tool was used in a case project where a mobile application for real markets was produced. The tool was dropped by the team only after two releases. The reasons of the process improvement failure are addressed in this paper. The principal results show that the tool was found to be too difficult to use and that it failed to provide as powerful a visual view as the paper-pen board method. The implications of these findings are addressed for both the practitioners and researchers in the field.
The Design and Implementation of An OGSA-based Grid Information Service
Authors: Tianyi Zang, Wei Jie, Terence Hung, Zhou Lei, Stephen J. Turner, Wentong Cai
Venue: Proceedings of the IEEE International Conference on Web Services (2004)

The information service is a key component of aGrid environment and critical to the operation of acomputational Grid. In this work, an OGSA (OpenGrid Services Architecture) based Information Servicethat complies with OGSI (Open Grid ServicesInfrastructure) is presented. The main functionality ofthis Information Service is the provision of informationessential for applications running on a computationalGrid such as resource information, job status, resourceworkload, service meta-information, and queue status.This OGSI-compliant Information Service is built onGlobus Toolkit MDS-3, and it works with meta-schedulingservices and local job scheduling systemsto support resource discovery, job scheduling, andexecution management. In this paper, the architectureof the Information Service and the models ofinformation data organization are presented. Someimplementation issues are discussed as well.
Cluster scheduling for explicitly-speculative tasks
Authors: David Petrou, Gregory R. Ganger, Garth A. Gibson
Venue: Proceedings of the 18th annual international conference on Supercomputing (2004)

Large-scale computing often consists of many speculative tasks to test hypotheses, search for insights, and review potentially finished products. E.g., speculative tasks are issued by bioinformaticists comparing DNA sequences and computer graphics artists adjusting scene properties. We promote a way of working that exploits the inherent speculation in application-level search made more common by the cost-effectiveness of grid and cluster computing. Researchers and end-users disclose sets of speculative tasks that search an application space, request specific results as needed, and cancel unfinished tasks if early results suggest no need to continue. Doing so matches natural usage patterns, making users more effective, and also enables a new class of schedulers.In simulation, we show how batchactive schedulers reduce user-observed response times relative to conventional models in which tasks are requested one at a time (interactively) or in batches without specifying which tasks are speculative. Over a range of situations, user-observed response time is about 50% better on average and at least two times better for 20% of our simulations. Moreover, we show how user costs can be reduced under an incentive cost model of charging only for tasks whose results are requested.
Implementing the defect prevention process in the MVS interactive programming organization
Authors: J. L. Gale, J. R. Tiso, C. A. Burchfield
Venue: IBM Systems Journal (1990)

A process for preventing defects has been gaining momentum in the IBM Corporation as a way to improve quality and increase productivity. The Communications Programming Laboratory in Research Triangle Park, North Carolina (near Raleigh), has been implementing the process for the past six years and has realized a 54 percent reduction in errors. This paper documents experiences at the IBM Myers Corners Laboratory MVS Interactive programming area in putting the Defect Prevention Process theories into practice. This paper begins with the proposal to adopt the Defect Prevention Process at the Myers Corners Laboratory in Poughkeepsie, New York, and our experiences thus far. It is our belief that other organizations can benefit from our experiences by understanding how the Defect Prevention Process can be adapted to best meet the needs of any organization.
The output of a cache under the independent reference model: where did the locality of reference go?
Authors: Sarut Vanichpun, Armand M. Makowski
Venue: ACM SIGMETRICS Performance Evaluation Review (2004)

We consider a cache operating under a demand-driven replacement policy when document requests are modeled according to the Independent Reference Model (IRM). We characterize the popularity pmf of the stream of misses from the cache, the so-called output of the cache, for a large class of demand-driven cache replacement policies. We measure strength of locality of reference in a stream of requests through the skewness of its popularity distribution. Using the notion of majorization to capture this degree of skewness, we show that for the policy A0 and the random policy, the output always has less locality of reference than the input. However, we show by counterexamples that this is not always the case under the LRU and CLIMB policies when the input is selected according to a Zipf-like pmf. In that case, conjectures are offered (and supported by simulations) as to when LRU or CLIMB caching indeed reduces locality of reference.
Three-Dimensional Layers of Maxima
Authors: Adam L. Buchsbaum, Michael T. Goodrich
Venue: Algorithmica (2004)

We present an O(n log n)-time algorithm to solve the three-dimensional layers-of-maxima problem. This is an improvement over the prior O(n log n log log n)-time solution. A previous claimed O(n log n)-time solution due to Atallah et al. has technical flaws. Our algorithm is based on a common framework underlying previous work, but to implement it we devise a new data structure to solve a special case of dynamic planar point location in a staircase subdivision. Our data structure itself relies on a new extension to dynamic fractional cascading that allows vertices of high degree in the control graph.
Multi-linear formulas for permanent and determinant are of super-polynomial size
Authors: Ran Raz
Venue: Proceedings of the thirty-sixth annual ACM symposium on Theory of computing (2004)

An arithmetic formula is multi-linear if the polynomial computed by each of its sub-formulas is multi-linear. We prove that any multi-linear arithmetic formula for the permanent or the determinant of an n x n matrix is of size super-polynomial in n.Previously, super-polynomial lower bounds were not known (for any explicit function) even for the special case of multi-linear formulas of constant depth.
A Complex Systems Approach to Service Discovery
Authors: Ricky Robinson, Jadwiga Indulska
Venue: Proceedings of the Database and Expert Systems Applications, 15th International Workshop (2004)

Complex systems are those systems composed of many, often very simple, interacting autonomous entities. Interactions between these entities give rise to behaviour and patterns at the global level that cannot be predicted by examining the behaviour of any single individual component in the system. By this definition, pervasive computing environments are complex systems. This paper develops the idea that complex systems theory can aid the design of service discovery, and that results from the field of complex networks research can be applied to service discovery protocols to improve their scalability and robustness. We describe the influences of complex systems theory on the design of an existing service discovery protocol for pervasive computing environments, and show that the application of complex systems ideas can improve scalability, performance and robustness of service discovery protocols.
Imperfect and Nonideal Clutters: A Common Approach
Authors: Grigor Gasparyan, Myriam Preissmann, Andr&#x00e1;s Seb&#x0151;
Venue: Combinatorica (2003)

We prove three theorems. First, Lov&#x00e1;sz&#x2019;s theorem about minimal imperfect clutters, including also Padberg&#x2019;s corollaries. Second, Lehman&#x2019;s result on minimal nonideal clutters. Third, a common generalization of these two. The endeavor of working out a &#x2018;common denominator&#x2019; for Lov&#x00e1;sz&#x2019;s and Lehman&#x2019;s theorems leads, besides the common generalization, to a better understanding and simple polyhedral proofs of both.
Low latency and cheat-proof event ordering for peer-to-peer games
Authors: Chris GauthierDickey, Daniel Zappala, Virginia Lo, James Marr
Venue: Proceedings of the 14th international workshop on Network and operating systems support for digital audio and video (2004)

We are developing a distributed architecture for massively-multiplayer games. In this paper, we focus on designing a low-latency event ordering protocol, called NEO, for this architecture. Previous event ordering protocols prevent several types of cheats at the expense of operating at the latency of the slowest player. We broaden the definition of cheating to include four common protocol level cheats and demonstrate how NEO prevents these cheats. At the same time, NEO has a playout latency independent of network conditions and adapts to network congestion to optimize performance.
Incremental elaboration of scenario-based specifications and behavior models using implied scenarios
Authors: Sebastian Uchitel, Jeff Kramer, Jeff Magee
Venue: ACM Transactions on Software Engineering and Methodology (TOSEM) (2004)

Behavior modeling has proved to be successful in helping uncover design flaws of concurrent and distributed systems. Nevertheless, it has not had a widespread impact on practitioners because model construction remains a difficult task and because the benefits of behavior analysis appear at the end of the model construction effort. In contrast, scenario-based specifications have a wide acceptance in industry and are well suited for developing first approximations of intended behavior; however, they are still maturing with respect to rigorous semantics and analysis tools.This article proposes a process for elaborating system behavior that exploits the potential benefits of behavior modeling and scenario-based specifications yet ameliorates their shortcomings. The concept that drives the elaboration process is that of implied scenarios. Implied scenarios identify gaps in scenario-based specifications that arise from specifying the global behavior of a system that will be implemented component-wise. They are the result of a mismatch between the behavioral and architectural aspects of scenario-based specifications. Due to the partial nature of scenario-based specifications, implied scenarios need to be validated as desired or undesired behavior. The scenario specifications are then updated accordingly with new positive or negative scenarios. By iteratively detecting and validating implied scenarios, it is possible to incrementally elaborate the behavior described both in the scenario-based specification and models. The proposed elaboration process starts with a message sequence chart (MSC) specification that includes basic, high-level and negative MSCs. Implied scenario detection is performed by synthesis and automated analysis of behavior models. The final outcome consists of four artifacts: (1) an MSC specification that has been evolved from its original form to cover important aspects of the concurrent nature of the system that were under-specified or absent in the original specification, (2) a behavior model that captures the component structure of the system that, combined with (3) a constraint model and (4) a property model that provides the basis for modeling and reasoning about system design.
Self-tuning Speculation for Maintaining the Consistency of Client-Cached Data
Authors: Keqiang Wu, David J. Lilja
Venue: Proceedings of the Parallel and Distributed Systems, Tenth International Conference (2004)

This paper presents a new protocol, Self-tuning ActiveData-aware Cache Consistency (SADCC), which employsparallel communication and self-tuning speculation toimprove the performance of data-shipping database systems.Using parallel communication with simultaneous client-serverand client-client communication, SADCC reduces thenetwork latency for detecting data conflicts by 50%, whileincreasing message volume overhead by only about 4.8%. Bybeing aware of the global states of cached data, clients self-tunebetween optimistic and pessimistic consistency control.The abort rate is reduced by statistically quantifying thespeculation cost. We compare SADCC with the leadingcache consistency algorithms, Active Data-aware CacheConsistency (ADCC) and Asynchronous Avoidance-basedCache Consistency (AACC), in a page server DBMSarchitecture with page-level consistency. The experimentsshow that, in a non-contention environment, both SADCCand ADCC display a slight reduction (an average of 2.3%)in performance compared to AACC with a high-speednetwork environment. With high contention, however,SADCC has an average of 14% higher throughput thanAACC and 6% higher throughput than ADCC.
Flexible Querying of Semi-Structured Information
Authors: Gabriella Pasi
Venue: Proceedings of the Database and Expert Systems Applications, 15th International Workshop (2004)

The problem of dealing with semi-structured information is an increasingly studied topic by both communities of researchers in Database Management and in Information Retrieval.DBMS and IRSs are the two main types of systems aimed at representing, storing and retrieving information.When semi-structured information is considered, the main problems addressed in the design of these systems are to represent and to inquiry semi-structured data and structured documents respectively.