ppxscal/embedding_network huggingface dataset:
Time-series similarity problems and well-separated geometric sets
Authors: Béla Bollobás, Gautam Das, Dimitrios Gunopulos, Heikki Mannila
Venue: Nordic Journal of Computing (2001)

Given a pair of nonidentical complex objects, defining (and determining) how similar they are to each other is a nontrivial problem. In data mining applications, one frequently needs to determine the similarity between two time series. We analyze a model of time-series similarity that allows outliers, different scaling functions, and variable sampling rates. We present several deterministic and randomized algorithms for computing this notion of similarity. The algorithms are based on nontrivial tools and methods from computational geometry. In particular, we use properties of families of well-separated geometric sets. The randomized algorithm has provably good performance and also works extremely efficiently in practice.
On Mutually Interfering Parallel Servers Subject to External Disturbances
Authors: Kimberly M. Wasserman, Tava Lennon Olsen
Venue: Operations Research (2001)

This paper considers a continuous-time non-Markovian parallel queueing system subject to external disturbances. The servers are mutually interfering in that their service rates are nonlinearly interdependent functions of the controls applied by the servers, and external discrete-valued continuous-time random disturbances. At certain time epochs, namely, every ? time units, the servers may adjust their service rates by changing the values of their controls; however, the system may change its state several times between successive decision epochs. The stability region of the system is established and a service rate control policy p* is provided, where an arrival rate vector in the interior of the region is sufficient for stability under p*, and a vector in the closure is necessary for stability under any policy. The stability region depends on ? and the variations of the disturbances between decision epochs, and p* does not require knowledge of the arrival rates. The stability region is not in general monotonic in ?, but under perfect continuous control (? = 0) the stability region is a superset of that under ? > 0. This queueing model captures essential features of resource allocation and stochastic control problems encountered in a number of telecommunication, transportation, and manufacturing systems.
On the invertibility of time series models
Authors: C. W. J. Granger, Allan Andersen
Venue: Essays in econometrics: Spectral analysis, seasonality, nonlinearity, methodology, and forecasting (2001)

A generalized definition of invertibility is proposed and applied to linear, non-linear and bilinear models. It is shown that some recently studied non-linear models are not invertible, but conditions for invertibility can be achieved for the other models.
Performance evaluation of an admission control algorithm: dynamic threshold with negotiation
Authors: Sheng-Tzong Cheng, Chi-Ming Chen, Ing-Ray Chen
Venue: Performance Evaluation (2003)

An admission control algorithm for a multimedia server is responsible for determining if a new request can be accepted without violating the QoS requirements of the existing requests in the system. Most admission control algorithms treat every request uniformly and hence optimize the system performance by maximizing the number of admitted and served requests. In practice, requests might have different levels of importance to the system. Requests offering high contribution or reward to the system performance deserve priority treatment. Failure of accepting a high-priority request would incur high penalty to the system.A novel threshold-based admission control algorithm with negotiation for two priority classes of requests is proposed in our previous study. The server capacity is divided into three partitions based on the threshold values: one for each class of requests and one common pool shared by two classes of requests. Reward and penalty are adopted in the proposed system model. High-priority requests are associated with higher values of reward as well as penalty than low-priority ones. In this paper, given the characteristics of the system workload, the proposed analytical models aim to finds the best partitions, optimizing the system performance based on the objective function of the total reward minus the total penalty. The negotiation mechanism reduces the QoS requirements of several low-priority clients, by cutting out a small fraction of the assigned server capacity, to accept a new high-priority client and to achieve a higher net earning value. Stochastic Petri-Net model is used to find the optimal threshold values and two analytical methods are developed to find sub-optimal settings. The experiment results show that the sub-optimal solutions found by the proposed analytical methods are very close to optimal ones. The methods enable the algorithm to dynamically adjust the threshold values, based on the characteristics of the system workload, to achieve higher system performance.
Kernel mode Linux
Authors: Toshiyuki Maeda
Venue: Linux Journal (2003)

Run any program in kernel space for maximum speed, but use your new power responsibly.
Solving Parallel Machine Scheduling Problems by Column Generation
Authors: Zhi-Long Chen, Warren B. Powell
Venue: INFORMS Journal on Computing (1999)

We consider a class of problems of scheduling n jobs on m identical, uniform, or unrelated parallel machines with an objective of minimizing an additive criterion. We propose a decomposition approach for solving these problems exactly. The decomposition approach first formulates these problems as an integer program, and then reformulates the integer program, using Dantzig-Wolfe decomposition, as a set partitioning problem. Based on this set partitioning formulation, branch-and-bound exact solution algorithms can be designed for these problems. In such a branch-and-bound tree, each node is the linear relaxation problem of a set partitioning problem. This linear relaxation problem is solved by a column generation approach where each column represents a schedule on one machine and is generated by solving a single machine subproblem. Branching is conducted on variables in the original integer programming formulation instead of variables in the set partitioning formulation such that single machine subproblems are more tractable. We apply this decomposition approach to two particular problems: the total weighted completion time problem and the weighted number of tardy jobs problem. The computational results indicate that the decomposition approach is promising and capable of solving large problems.
Object-oriented concept mapping using UML class diagrams
Authors: Ernest Ferguson
Venue: Journal of Computing Sciences in Colleges (2003)

Concept maps have proven beneficial in the assessment of students' preconceptions and mental models in the natural sciences. This paper examines if it is possible to create concept-map class diagrams from the Unified Modeling Language to assess student's mental models upon entry into a course and to monitor their development throughout the course. Perhaps the use of UML in the cognitive area will facilitate students' understanding of object-oriented software design. Hopefully the mental models obtained can make instructional designers cognizant of the common misconceptions and pitfalls students have in the conceptually challenging area of object-oriented software design.
Forecasting the US unemployment rate
Authors: Tommaso Proietti
Venue: Computational Statistics Data Analysis (2003)

The primary interest is in out-of-sample forecasting of the US monthly unemployment rate. Several linear unobserved components models are fitted and their comparative forecasting accuracy is assessed by means of an extensive rolling-origin procedure using a test period that covers the last two decades. An attempt is made to link forecasting performance to the time domain properties of the models and the evidence is that highly persistent models perform better. Deletion diagnostics and normality tests, along with documenting possible departures from linearity and Gaussianity attributable to business cycle and turning point asymmetries, foster the conclusion that these are mostly concentrated in the pre-forecast period (1948-1980). A search is made for plausible nonlinear extensions capable of accounting for dynamic asymmetries in unemployment rates, leading to the specification of a cyclical trend model with smooth transition in the underlying parameters that improves forecast accuracy at short lead times and at the end of the sample period; as expected, though significant, the gains are not exceptionally large. The generalised impulse response function casts some light on the interpretation of the results. In particular, the main evidence is that persistence is not a stable feature over the business cycle.
Invariants of fold-maps via stable homotopy groups
Authors: Yoshifumi Ando
Venue: Publications of the Research Institute for Mathematical Sciences (2002)

In the 2-jet space J2(n,p) of smooth map germs (Rn, 0) → (Rp, 0) with n ≥ p ≥ 2, we consider the subspace Ωn-p+1,0(n,p) consisting of all 2-jets of regular germs and map germs with fold singularities. In this paper we determine the homotopy type of the space Ωn-p+1,0(n,p). Let N and P be smooth (C∞) manifolds of dimensions n and p. A smooth map f : N → P is called a fold-map if f has only fold singularities. We will prove that this homotopy type is very useful in finding invariants of fold-maps. For instance, by applying the homotopy principle for fold-maps in [An3] and [An4] we prove that if n - p + 1 is odd and P is connected, then there exists a surjection of the set of cobordism classes of fold-maps into P to the stable homotopy group limk,l → ∞πn+k+l(T(vPk) ∧ T (γGn-p+1,ll)). Here, vPk is the normal bundle of P in Rp+k and γGn-p+1,ll denote the canonical vector bundles of dimension l over the grassman manifold Gn-p+l,l. We also prove the oriented version.
Optimal Commonality in Component Design
Authors: Ulrich W. Thonemann, Margaret L. Brandeau
Venue: Operations Research (2000)

Increased competition and more demanding customers have forced companies to offer a wide variety of products. Component commonality can help companies reduce the cost of providing product variety to their customers. However, determining the extent to which component commonality should be used is difficult. In this paper we present an approach to determine the optimal level of component commonality for end-product components that do not differentiate models from the customer's perspective. The work was inspired by and applied to a wire-harness design problem faced by a major automobile manufacturer. We model the component design problem as a mathematical program that considers production, inventory holding, setup, and complexity costs (the cost in indirect functions caused by component variety). We develop two approaches to solve the problem: a branch-and-bound algorithm that can solve small- and medium-size problems optimally, and a simulated annealing algorithm that can solve large-size problems heuristically. We apply both algorithms to the wireharness design problem faced by the automobile manufacturer and to a number of randomly generated test problems. We show that an optimal design achieves high cost savings by using significantly fewer variants than a no-commonality design but significantly more variants than a full-commonality design. We apply sensitivity analysis to identify extreme conditions under which the no-commonality and full-commonality designs perform well, and we identify the key cost drivers for our application. Finally, we describe the impact of our analysis on the company's subsequent component design decisions.
The Stochastic Economic Lot Scheduling Problem: Heavy Traffic Analysis of Dynamic Cyclic Policies
Authors: David M. Markowitz, Martin I. Reiman, Lawrence M. Wein
Venue: Operations Research (2000)

We consider two queueing control problems that are stochastic versions of the economic lot scheduling problem: A single server processesN customer classes, and completed units enter a finished goods inventory that services exogenous customer demand. Unsatisfied demand is backordered, and each class has its own general service time distribution, renewal demand process, and holding and backordering cost rates. In the first problem, a setup cost is incurred when the server switches class, and the setup cost is replaced by a setup time in the second problem. In both problems we employ a long-run average cost criterion and restrict ourselves to a class of dynamic cyclic policies, where idle periods and lot sizes are state-dependent, but theN classes must be served in a fixed sequence. Motivated by existing heavy traffic limit theorems, we make a time scale decomposition assumption that allows us to approximate these scheduling problems by diffusion control problems. Our analysis of the approximating setup cost problem yields a closed-form dynamic lot-sizing policy and a computational procedure for an idling threshold. We derive structural results and an algorithmic procedure for the setup time problem. A computational study compares the proposed policy and several alternative policies to the numerically computed optimal policy.
Asymptotic expansion of the null distribution of test statistic for linear hypothesis in nonnormal linear model
Authors: Hirokazu Yanagihara
Venue: Journal of Multivariate Analysis (2003)

This paper is concerned with the null distribution of test statistic T for testing a linear hypothesis in a linear model without assuming normal errors. The test statistic includes typical ANOVA test statistics. It is known that the null distribution of T converges to χ2 when the sample size n is large under an adequate condition of the design matrix. We extend this result by obtaining an asymptotic expansion under general condition. Next, asymptotic expansions of one- and two-way test statistics are obtained by using this general one. Numerical accuracies are studied for some approximations of percent points and actual test sizes of T for two-way ANOVA test case based on the limiting distribution and an asymptotic expansion.
Discrete location problems with push-pull objectives
Authors: Jakob Krarup, David Pisinger, Frank Plastria
Venue: Discrete Applied Mathematics (2002)

The models within operational research concerned with locational decisions mostly either consider only the positive effects, pulling the facilities towards demand, or only negative effects, pushing the facilities away from the places affected by the facilities' nearness. In real-world situations both of these opposing forces are at work. We give an overview of a number of push-pull models, yielding alternative ways to incorporate both types of effects simultaneously. The discussion is restricted to models of combinatorial optimisation and includes indications of reduction to standard models and/or algorithmic approaches where possible.
Application scenarios for scientific visualization and virtual reality using a CAVE infrastructure
Authors: Ch. Stern, H. Noser, J. Weissmann, P. Stucki
Venue: Proceedings of the workshop on Virtual environments 2003 (2003)

Today's Virtual Reality applications require a high degree of immersion. This may be achieved by using a CAVE incorporating powerful 3D computer graphics workstations, panoramic multiple screen displays and projection walls, stereovision and interaction devices such as trackers and data gloves. This article describes Virtual Reality applications from the fields of scientific visualization in medicine and education embedded within the Blue-C environment, a state-of-the-art CAVE infrastructure.
The Paderborn University BSP (PUB) library
Authors: Olaf Bonorden, Ben Juurlink, Ingo von Otte, Ingo Rieping
Venue: Parallel Computing (2003)

The Paderborn University BSP (PUB) library is a C communication library based on the BSP model. The basic library supports buffered as well as unbuffered non-blocking communication between any pair of processors and a mechanism for synchronizing the processors in a barrier style. In addition, PUB provides non-blocking collective communication operations on arbitrary subsets of processors, the ability to partition the processors into independent groups that execute asynchronously from each other, and a zero-cost synchronization mechanism. Furthermore, some techniques used in the implementation of the PUB library deviate significantly from the techniques used in other BSP libraries.
No usability test is an island: is our expertise enough on its own?
Authors: Tim Westall
Venue: The usability business: making the web work (2001)

As technology products continue to offer more services to more types of user for more reasons, it's becoming harder and harder to make a living as an expert in only one area. When so many factors contribute to the way people respond to a web-site or a technology product, it seems increasingly that usability expertise is no longer enough in itself. Instead, experts in a number of specialities now need to know more about each other if they are to be able to give clients what they want. Branding, marketing, technology, consumer research and graphic design are mingling with each other and with usability to influence the way users experience technology - it's very difficult to apply one without an awareness of the other. This chapter illustrates the pitfalls of having too much as well as too little expertise, and argues for both a greater integration of skillsets and a deeper appreciation of expertise.
SmartPad: a finger-sensing keypad for mobile interaction
Authors: Jun Rekimoto, Haruo Oba, Takaaki Ishizawa
Venue: CHI '03 extended abstracts on Human factors in computing systems (2003)

This paper introduces SmartPad, a new input device for mobile computers that is an enhanced physical keypad by a finger position sensor. This input device acts as a normal keypad for mobile devices, such as cellular phones, and also recognizes finger position on the keypad be before the user presses the key. This feature is used to recognize finger gesture on the keypad, and can also be used to give preview information to the user before the user actually pressing the key. This previewable function helps users to predict the effect of the action, and it is also helpful when the key definitions are frequently changed according to the context, such as in the case of universal commanders.
Introduction of accounting capabilities in future service architectures
Authors: E. C. Tzifa, P. P. Demestichas, N. I. Liossis, N. D. Polydorou, M. E. Anagnostou
Venue: Journal of Systems and Software (2002)

This paper proposes enhancements to the accounting support capabilities of legacy, standardised service architectures. The TINA service architecture is used as a reference, even though our approach is applicable to other models as well. The key points in this paper are the following. First, the definition of minimal extensions to the standard service architecture components, so as to enable them to offer accounting information. Second, the definition of the interface among the extended service architecture components and the new components that will undertake the accounting functionality. Third, the definition of the functionality of the new components that will undertake the accounting functionality. New components are defined so as to minimally impact the specified service architecture.
On algebraic and logical specifications of classes of regular languages
Authors: Bakhadyr Khoussainov
Venue: Theoretical Computer Science (2003)

The paper studies classes of regular languages based on algebraic constraints imposed on transitions of automata and discusses issues related to specifications of these classes from algebraic, computational and logical points of view.
The equation a2(k+2,S(n))= a2(k+1,S(n))+ a2(k,S(n))
Authors: Xigeng Chen
Venue: Smarandache notions (2002)

For any positive integer a, let S(a) be the Smarandache function of a. For any positive integers r and b, let a(r,b) be the first r digits of b. In this paper we prove that the title equation has no positive integer solutions (n,k).
On Formal Semantics and Analysis of Typed Modeling Languages: An Analysis of Ascend
Authors: Hemant K. Bhargava, Ramayya Krishnan, Peter Piela
Venue: INFORMS Journal on Computing (1998)

The use of strong typing, exemplified in the Ascend modeling language, is a recent phenomenon in executable modeling languages for mathematical modeling. It is also one that has significant potential for improving the functionality of computer-based modeling environments. Besides being a strongly typed language, Ascend is unique in providing operators that allow dynamic type inference, a feature that has been shown to be useful in assisting model evolution and reuse. We develop formal semantics for the type system in Ascend-focusing on these operators-and analyze its mathematical and computational properties. We show that despite the strong interactions between various statements involving the operators, the language does possess certain desirable mathematical and computational properties. Further, our analysis identifies general issues in the design and implementation of type systems in mathematical modeling languages. The methods used in the article are applicable beyond Ascend to a class of typed modeling languages that may be developed in the future.
Complexity Theory and Organization Science
Authors: Gérard P. Cachon, Paul H. Zipkin, Philip Anderson
Venue: Organization Science (1999)

Complex organizations exhibit surprising, nonlinear behavior. Although organization scientists have studied complex organizations for many years, a developing set of conceptual and computational tools makes possible new approaches to modeling nonlinear interactions within and between organizations. Complex adaptive system models represent a genuinely new way of simplifying the complex. They are characterized by four key elements: agents with schemata, self-organizing networks sustained by importing energy, coevolution to the edge of chaos, and system evolution based on recombination. New types of models that incorporate these elements will push organization science forward by merging empirical observation with computational agent-based simulation. Applying complex adaptive systems models to strategic management leads to an emphasis on building systems that can rapidly evolve effective adaptive solutions. Strategic direction of complex organizations consists of establishing and modifying environments within which effective, improvised, self-organized solutions can evolve. Managers influence strategic behavior by altering the fitness landscape for local agents and reconfiguring the organizational architecture within which agents adapt.