ppxscal/embedding_network huggingface dataset:
Soft stratification for magic set based query evaluation in deductive databases
Authors: Andreas Behrend
Venue: Proceedings of the twenty-second ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems (2003)

In this paper we propose a new bottom-up query evaluation method for stratified deductive databases based on the Magic Set approach. As the Magic Sets rewriting may lead to unstratifiable rules, we propose to use Kerisit's weak consequence operator to compute the well-founded model of magic rules (guaranteed to be two-valued). We show that its application in combination with the concept weak stratification, however, may lead to a set of answers which is neither sound nor complete with respect to the well-founded model. This problem is cured by introducing the new concept soft stratification instead.
Special uniform approximations of continuous vector-valued functions.: part I: Special approximations in Cx(T)
Authors: Vlad Timofte
Venue: Journal of Approximation Theory (2002)

In this paper, we give special uniform approximations of functions u from the spaces Cx(T) and C∞(T,X), with elements u' of the tensor products CΓ(T)⊗ X, respectively C0(T, Γ) ⊗ X, for a topological space T and a Γ-locally convex space X. We call an approximation special, if u satisfies additional constraints, namely supp ν ⊂ u-1(X\{0}) and u'(T) ⊂ co(u(T)) (resp. ⊂ co(u(T) ∪ {0})). In Section 3, we give three distinct applications, which are due exactly to these constraints: a density result with respect to the inductive limit topology, a Tietze-Dugundji's type extension new theorem and a proof of Schander-Tihonov's fixed point theorem.
Navy Operations Research
Authors: Wayne P. Hughes
Venue: Operations Research (2002)

This paper emphasizes OR's utility to the U.S. Navy, as seen by its customers. Like many naval officers who subspecialized in operations research, the author was both producer and consumer of analysis toward improving fleet operations, Pentagon planning, and training effectiveness. Many of OR's unnoticed heroes are officers and Navy civilians who, then and now, could put operations analysis to best practical use. The paper reaches three conclusions, which (briefly) are: (1) The U.S. Navy could shift much analytical talent to improve fleet readiness and scarcely notice a loss of quality in Washington, (2) the benefit of Navy OR in the Pentagon was not so much in formal decision making as it was in educating a stream of future leaders about the state of the Navy and cost-constrained possible future states, and (3) the distinguishing contribution of all OR has been and still is in helping executives make better, timely decisions by applying our special art of quantitative analysis, and only incidentally in the fidelity or complexity of the models and other tools we employ.
On unilaterally supported viscoelastic von Kármán plates with a long memory
Authors: Igor Bock, Ján Lovíšek
Venue: Mathematics and Computers in Simulation (2003)

We deal with the system consisting of the nonlinear integro-differential variational inequality for the deflection and the nonlinear quasistationary equation for the Airy stress function. The system describes moderately large deflections with an inner obstacle of a thin viscoelastic plate made of a long memory material. The corresponding Volterra type canonical integro-differential variational inequality is solved using a semidiscrete approximation transforming the problem into the sequence of stationary variational inequalities of von Kármán type. The existence of a solution as well as the convergence of a semidiscrete approximation to a solution of the Volterra variational inequality with a nonlinear main part are verified.
Customer Referral Management: Optimal Reward Programs
Authors: Eyal Biyalogorsky, Eitan Gerstner, Barak Libai
Venue: Marketing Science (2000)

Sellers who plan to capitalize on the lifetime value of customers need to manage the sales potential from customer referrals proactively. To encourage existing customers to generate referrals, a seller can offer exceptional value to current customers through either excellent quality or a very attractive price. Rewards to customers for referring other customers can also encourage referrals. We investigate when referral rewards should be offered to motivate referrals and derive the optimal combination of reward and price that will lead to the most profitable referrals.We define a delighted customer as one who obtains a positive level of surplus above a threshold level and, consequently, recommends the product to another customer. We show that the use of referral rewards depends on how demanding consumers are before they are willing to recommend (i.e., on the delight threshold level). The optimal mix of price and referral reward falls into three regions: (1) When customers are easy to delight, the optimal strategy is to lower the price below that of a seller who ignores the referral effect but not to offer rewards. (2) In an intermediate level of customer delight threshold, a seller should use a reward to complement a low-price strategy. As the delight threshold gets higher in this region, price should be higher and the rewards should be raised. (3) When the delight threshold is even higher, the seller should forsake the referral strategy all together. No rewards should be given, and price reverts back to that of a seller who ignores referrals. These results are consistent with the fact that referral rewards are not offered in all markets.Our analysis highlights the differences between lowering price and offering rewards as tools to motivate referrals. Lowering price is attractive because the seller "kills two birds with one stone": a lower price increases the probability of an initial purchase and the likelihood of referral. Unfortunately, a low price also creates a "free-riding" problem, because some customers benefit from the low price but do not refer other customers. Free riding becomes more severe with an increasing delight threshold; therefore, motivating referrals through low price is less attractive at high threshold levels. A referral reward helps to alleviate this problem, because of its "pay for performance" incentive (only actual referrals are rewarded.) Unfortunately, rewards can sometimes be given to customers who would have recommended anyway, causing a waste of company resources. The lower the delight threshold level, the bigger the waste and, therefore, motivating referrals through rewards loses attractiveness.Our theory highlights the advantage of using referral rewards in addition to lowering price to motivate referrals. It explains why referral programs are offered sometimes but not always and provides guidelines to managers on how to set the price and reward optimally.
Multilocation Combined Pricing and Inventory Control
Authors: Awi Federgruen, Aliza Heching
Venue: Manufacturing Service Operations Management (2002)

We consider the problem of managing inventories and dynamically adjusting retailer prices in distribution systems with geographically dispersed retailers. More specifically, we analyze the following single item, periodic review model. The distribution of demand in each period, at a given retailer, depends on the item's price according to a stochastic demand function. These stochastic demand functions may vary by retailer and by period. The replenishment process consists of two phases: In some or all periods, a distribution center may place an order with an outside supplier. This order arrives at the distribution center after an "order leadtime" and is then, in the second phase, allocated to the retailers. Allocations arrive after a second "allocation leadtime."We develop an approximate model that is tractable and in which an optimal policy of simple structure exists. The approximate model thus provides analytically computable approximations for systemwide profits and other performance measures. Moreover, the approximate model allows us to prove how various components of the optimal strategy (i.e., prices and order-up-to levels) respond to shifts in the model parameters, e.g., to shifts in the retailers' demand functions. In addition, we develop combined pricing, ordering, and allocation strategies and show that the system's performance under these strategies is well gauged by the above approximations. We use this model to assess the impact of different types of geographic dispersion on systems with dynamically varying prices and how different system parameters (e.g., leadtimes, coefficients of variation of individual retailers' demand, price elasticities) contribute to this impact. Similarly, we use the model to gauge the benefits of coordinated replenishments under dynamic pricing, and how these benefits increase as the allocation decisions of the systemwide orders to individual retailers are postponed to a later point in the overall replenishment leadtime.We report on a comprehensive numerical study based on data obtained from a nationwide department store chain.
Krylov subspace techniques for reduced-order modeling of large-scale dynamical systems
Authors: Zhaojun Bai
Venue: Applied Numerical Mathematics (2002)

In recent years, a great deal of attention has been devoted to Krylov subspace techniques for reduced-order modeling of large-scale dynamical systems. The surge of interest was triggered by the pressing need for efficient numerical techniques for simulations of extremely large-scale dynamical systems arising from circuit simulation, structural dynamics, and microelectromechanical systems. In this paper, we begin with a tutorial of a Lanczos process based Krylov subspace technique for reduced-order modeling of linear dynamical systems, and then give an overview of the recent progress in other Krylov subspace techniques for a variety of dynamical systems, including second-order and nonlinear systems. Case studies arising from circuit simulation, structural dynamics and microelectromechanical systems are presented.
Customer relationship management at Harrah's entertainment
Authors: Hugh J. Watson, Linda Volonino
Venue: Decision making support systems: achievements, trends and challenges for (2002)

Data warehousing has significantly changed how decision making is supported in organizations. A leading application of data warehousing is customer relationship management (CRM). The power of CRM is illustrated by the experiences at Harrah's Entertainment, which has assumed a leadership role in the gaming industry through a business strategy that focuses on knowing their customers well, giving them great service, and rewarding their loyalty so that they seek out a Harrah's casino whenever and wherever they play.In 1993, changing gaming laws allowed Harrah's to expand into new markets through the building of new properties and the acquisition of other casinos. As management thought about how it could create the greatest value for its shareholders, it was decided that a brand approach should be taken. With this approach, the various casinos would operate in an integrated manner rather than as separate properties. Critical to their strategy was the need to understand and manage relationships with their customers. Harrah's had to understand where their customers gamed, how often and what games they played, how much they gambled, their profitability, and what offers would entice them to visit a Harrah's casino. Armed with this information, Harrah's could better identify specific target customer segments, respond to customers' preferences, and maximize profitability across the various casinos.In order to execute their business strategy, Harrah's made a substantial investment in information technology to create WINet. WINet sources data from casino, hotel, and event systems. The data is then integrated into a patron database that serves as an operational data store. The data store is used to support operations, such as facilitating the check-in of customers at Harrah's casinos. It is also used with "Total Rewards," Harrah's customer loyalty program. Customers accumulate reward credits based on their gaming and other activities at any Harrah's properties. These reward credits can be redeemed for cast of comps on hotel accommodations, meals, and shows. Data from the patron database is then loaded in the marketing workbench, which serves as Harrah's data warehouse. The marketing workbench supports analytical applications such as customer segmentation and profiling, and identifying customers to send offers to. WINet also provides the foundation for "closed loop marketing. " With this data-driven approach, campaigns are designed, tested, and the results retained for future use.Harrah's creative marketing, innovative uses of information technology, and operational excellence have resulted in many benefits, including a brand identity for Harrah's, consistent guest rewards and recognition across properties, a significant increase in the response rate to offers to customers, and great customer loyalty. Valuable lessons have been learned that can be applied by other companies embarking on a CRM initiative.
Seeds for random number generators
Authors: George Marsaglia
Venue: Communications of the ACM (2003)

Techniques for choosing seeds for social and scientific applications of random number generators.
Quantifying behavioral differences between multimedia and general-purpose workloads
Authors: Lieven Eeckhout, Koen De Bosschere
Venue: Journal of Systems Architecture: the EUROMICRO Journal (2003)

Multimedia workloads are becoming increasingly more common on general-purpose computing systems. However, little quantitative results are available about the behavior of these workloads. This paper is a first step in quantifying and understanding the behavioral differences (if any) between multimedia and general-purpose workloads. This is done by comparing program characteristics of multimedia applications (coming from the MediaBench suite, the X benchmarks from the SimpleScalar distribution, plus a set of MPEG-4 like algorithms) and general-purpose applications (coming from the SPECint95 and the SPECint2000 benchmark suite). In addition to presenting a database of program characteristics, we conclude that (i) multimedia applications have less memory operations and less control operations in their instruction mix than general-purpose workloads, and thus are computationally intensive; (ii) multimedia and general-purpose applications exhibit comparable levels of instruction-level parallelism; (iii) multimedia applications also suffer from hard-to-predict branches and (iv) the instruction stream as well as the data stream of multimedia applications exhibit more spatial and more temporal locality than general-purpose applications. These results were obtained using statistical tests, namely the t-test and the Mann-Whitney test.
Software radio system design for accessing wireless multimedia services
Authors: Ming-Chung Tang, R. C. Chang, Wei-Kuan Shih
Venue: Information processing and technology (2001)

This paper presents a software engineer's perspective for the design and implementation of a software radio (SWR) system. The key technical challenge that we want to address is the architecture design of a software radio system and the QoS control for multimedia processing in this architecture. We propose the component-binding based software radio architecture and the QoS-controllable scheduling mechanism (QSM) in this paper. The component-binding based software radio architecture comprises four parts: the control-flow components, the data-flow components, the reconfigurable binding interface, and the SWR management unit (SMU). The QoS-controllable scheduling mechanism applies imprecise computation techniques for SMU to ensure that time-critical tasks can meet their deadlines and multimedia services can meet their QoS requirements. QSM is coarse-and-fine adjustable. Also, we investigate the k-tasks-look-ahead substitutable check to further enhance the overall schedulability for the on-line scheduler in QSM. By taking advantage of programmability, the proposed system architecture can serve as a flexible platform for supporting the accessing and processing of wireless multimedia services.
On transitive Cayley graphs of groups and semigroups
Authors: Andrei V. Kelarev, Cheryl E. Praeger
Venue: European Journal of Combinatorics (2003)

We investigate Cayley graphs of semigroups and show that they sometimes enjoy properties analogous to those of the Cayley graphs of groups.
Using importances in group preference aggregation to block strategic manipulation
Authors: Ronald R. Yager
Venue: Aggregation operators: new trends and applications (2002)

We consider the problem of preference aggregation in group decision making. The role of the collaborative imperative used by the group in determining the form of the aggregation function is noted. We focus on one collaborative imperative, called the primal, deriving from participant autonomy, an agent doesn't have to accept a decision by the group it doesn't like. We showed that t-norms and more generally the class of uninorms having zero fixation provide appropriate aggregation operators to implement this primal collaborative imperative. We then discuss the possibility of an agent using a strategic manipulation of its preference information to get its preferred alternative. A mechanism based upon the use of an importance weighting is then suggested for modifying the construction of the group decision function to defend against strategic manipulation.
The algorithmics of folding proteins on lattices
Authors: Vijay Chandru, Abhi DattaSharma, V. S. Anil Kumar
Venue: Discrete Applied Mathematics (2003)

It should be possible to predict the fold of a protein into its native conformation, once we are given the sequence of the constituent amino acids. This is known as the protein structure prediction problem and is sometimes referred to as the problem of deciphering the second half of the genetic code. While large proteins fold in nature in seconds, computational chemists and biologists have found that folding proteins to their minimum energy conformations is a challenging unsolved optimization problem. Computational complexity theory has been useful in explaining, at least partially, this (Levinthal's) paradox. The pedagogic cross-disciplinary survey by Ngo, Marks and Karplus (Computational Complexity, Protein Structure Prediction and the Levinthal Paradox, Birkhauser, Basel, 1994) provides an excellent starting point for nonbiologists to take a plunge into the problem of folding proteins. Since then, there has been remarkable progress in the algorithmics of folding proteins on discrete lattice models, an account of which is presented herein.
High speed associative memories for feature extraction and visualisation
Authors: Aistis Raudys
Venue: Pattern Recognition Letters (2003)

New feature extraction method that handles nonlinearly separable datasets, preserves data geometry, minimises classification error directly and is designed especially for visualisation is suggested. The method employs hardware friendly binary correlation matrix memories (CMM), which makes the algorithm itself hardware friendly. To find coefficients of optimal linear orthogonal transformation and to speed up the calculations, binary CMM classifier and modified genetic optimisation technique are applied. The proposed technique was verified and compared with four competitive mapping techniques over a dozen of artificial and real world datasets. Experiments performed with respect to visualisation and classification accuracy showed that method is preferable to use on average sized nonlinear problems for extracting two features on behalf of visualisation.
Ecoulements externes de Stokes dans des domaines non réguliers et condition de Kutta-Joukowski généralisée
Authors: Fulgence Razafimahery
Venue: Zeitschrift f&uuml;r Angewandte Mathematik und Physik (ZAMP) (2003)

The aim of this work is to calculate the plane Stokes flows acting in the unbounded domains surrounding a given profil P presenting a trailing edge T. In order to have bounded pressure and bounded vorticity at T, we equate to zero the first derivative of the velocity: this condition is the generalized Kutta-Joukowski condition.
Network interface multicast protocols for wormhole-based networks of workstations
Authors: Cosimo Anglano, Claudio Casetti, Emilio Leonardi, Fabio Neri
Venue: Parallel Computing (2003)

Wormhole-routing high-speed local area networks (e.g., Myrinet), increasingly used to build high-performance Network of Workstations, do not usually provide hardware support to multicast communication, that must instead be implemented in software by sending several point-to-point messages. Network Interface protocols allow an efficient software implementation of multicast communication, but require flow control techniques (to avoid buffer overflows) that may lead to a severe performance degradation. In this paper we address the problem of designing reliable and efficient Network Interface multicast protocols. We propose a flow control technique that provides the basis for four multicast protocols, and we perform extensive simulations to characterize the impact that various factors (such as network topology, presence of unicast traffic, composition of multicast groups, etc.) have on their performance. Interestingly, our simulation experiments sometimes lead to observations that are in contrast with previous results. In particular, the most simple multicasting algorithms (e.g., separate addressing) may outperform sophisticated algorithms usually considered more effective, such as those based on spanning-trees.
Quantitative visual impact assessment using three-dimensional computer modelling
Authors: C. J. B. Cox, D. Schofield
Venue: Development and application of computer techniques to environmental studies (2002)

For the past 10 years, the AIMS Research Unit at the University of Nottingham, has employed Computer Graphics (CG) and Virtual Reality (VR) in civilian and industrial contexts for environmental and design visualisation, accident reconstruction, risk analysis, data visualisation and training simulators. It is recognised that Visual Impact Assessment (VIA), unlike many other aspects of Environmental Impact Assessments (EIA), relies less upon measurement than upon experience and judgement. Hence it is necessary for a more structured and consistent approach towards VIA, reducing the amount of bias and subjectivity.For proposed developments, there are very few quantitative techniques for the evaluation of visibility, and these existing methods can be highly inaccurate and time consuming. Percentage view changes are one of the few quantitative techniques, and the use of computer graphics in this field can reduce the inaccuracy and the time spent evaluating the visibility of either existing or proposed developments.This paper describes a method to quantitatively assess the visual impact of proposed developments on the landscape using CG techniques. This method allows the determination of accurate percentage view changes with the use of a computer generated model of the environment and the application of specialist software that has been developed by the University of Nottingham. The principles are easy to understand and therefore planners, authorisation agencies and members of the public can use and understand the results. A case study is shown to demonstrate the application and the capabilities of the technology.