ppxscal/embedding_network huggingface dataset:
Cost estimation of user-defined methods in object-relational database systems
Authors: Jihad Boulos, Kinji Ono
Venue: ACM SIGMOD Record (1999)

In this paper we present a novel technique for cost estimation of user-defined methods in advanced database systems. This technique is based on multi-dimensional histograms. We explain how the system collects statistics on the method that a database user defines and adds to the system. From these statistics a multi-dimensional histogram is built. Afterwards, this histrogram can be used for estimating the cost of the target method whenever this method is referenced in a query. This cost estimation is needed by the optimizer of the database system since this cost estimation needs to know the cost of a method in order to place it at its optimal position in the Query Execution Plan (QEP). We explain here how our technique works and we provide an example to better verify its functionality.
Bubbles and Market Crashes
Authors: Michael Youssefmir, Bernardo A. Huberman, Tad Hogg
Venue: Computational Economics (1998)

We present a dynamical theory of asset price bubbles that exhibits the appearance of bubbles and their subsequent crashes. We show that when speculative trends dominate over fundamental beliefs, bubbles form, leading to the growth of asset prices away from their fundamental value. This growth makes the system increasingly susceptible to any exogenous shock, thus eventually precipitating a crash. We also present computer experiments which in their aggregate behavior confirm the predictions of the theory.
Central Paths, Generalized Proximal Point Methods, and Cauchy Trajectories in Riemannian Manifolds
Authors: Alfredo N. Iusem, B. F. Svaiter, João Xavierda Cruz
Venue: SIAM Journal on Control and Optimization (1999)

We study the relationships between three concepts which arise in connection with variational inequality problems: central paths defined by arbitrary barriers, generalized proximal point methods (where a Bregman distance substitutes for the Euclidean one), and Cauchy trajectory in Riemannian manifolds. First we prove that under rather general hypotheses the central path defined by a general barrier for a monotone variational inequality problem is well defined, bounded, and continuous and converges to the analytic center of the solution set (with respect to the given barrier), thus generalizing results which deal only with complementarity problems and with the logarithmic barrier. Next we prove that a sequence generated by the proximal point method with the Bregman distance naturally induced by the barrier function converges precisely to the same point. Furthermore, for a certain class of problems (including linear programming), such a sequence is contained in the central path, making the concepts of central path and generalized proximal point sequence virtually equivalent. Finally we prove that for this class of problems the central path also coincides with the Cauchy trajectory in the Riemannian manifold defined on the positive orthant by a metric given by the Hessian of the barrier (i.e., a curve whose direction at each point is the negative gradient of the objective function at that point in the Riemannian metric).
Assigning labels in unknown anonymous networks (extended abstract)
Authors: Pierre Fraigniaud, Andrzej Pelc, David Peleg, Stéphane Pérennes
Venue: Proceedings of the nineteenth annual ACM symposium on Principles of distributed computing (2000)

We consider the task of distributedly assigning distinct labels to nodes of an unknown anonymous network. A priori, nodes do not have any identities (anonymous network) and do not know the topology or the size of the network (unknown network). They execute identical algorithms, apart from a distinguished node, called the source, which starts the labeling process. Our goal is to assign short labels, as fast as possible. The quality of a labeling algorithm is measured by the range from which the algorithm picks the labels, or alternatively, the length of the assigned labels. Natural efficiency measures are the time, i.e., the number of rounds required for the label assignment, and the message and bit complexities of the label assignment protocol, i.e., the total number of messages (resp., bits) circulating in the network. We present label assignment algorithms whose time and message complexity are asymptotically optimal and which assign short labels. On the other hand, we establish inherent trade-offs between quality and efficiency for labeling algorithms.
Reduced Systems for Three-Dimensional Elliptic Equations with Variable Coefficients
Authors: Chen Greif
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

We consider large sparse nonsymmetric linear systems arising from finite difference discretization of three-dimensional (3D) convection-diffusion equations with variable coefficients. We show that performing one step of cyclic reduction yields a system of equations which is well conditioned and for which fast convergence can be obtained. A certain block ordering strategy is applied, and analytical results concerning symmetrizability conditions and bounds on convergence rates are given. The analysis is accompanied by numerical examples.
Inexact Preconditioned Conjugate Gradient Method with Inner-Outer Iteration
Authors: Gene H. Golub, Qiang Ye
Venue: SIAM Journal on Scientific Computing (1999)

An important variation of preconditioned conjugate gradient algorithms is inexact preconditioner implemented with inner-outer iterations [G. H. Golub and M. L. Overton, Numerical Analysis, Lecture Notes in Math. 912, Springer, Berlin, New York, 1982], where the preconditioner is solved by an inner iteration to a prescribed precision. In this paper, we formulate an inexact preconditioned conjugate gradient algorithm for a symmetric positive definite system and analyze its convergence property. We establish a linear convergence result using a local relation of residual norms. We also analyze the algorithm using a global equation and show that the algorithm may have the superlinear convergence property when the inner iteration is solved to high accuracy. The analysis is in agreement with observed numerical behavior of the algorithm. In particular, it suggests a heuristic choice of the stopping threshold for the inner iteration. Numerical examples are given to show the effectiveness of this choice and to compare the convergence bound.
A high-level abstraction of shared accesses
Authors: Peter J. Keleher
Venue: ACM Transactions on Computer Systems (TOCS) (2000)

We describe the design and use of the tape mechanism, a new high-level abstraction of accesses to shared data for software DSMs. Tapes consolidate and generalize a number of recent protocol optimizations, including update-based locks and recorded-replay barriers. Tapes are usually created by &ldquo;recording&rdquo; shared accesses. The resulting recordings can be used to anticipate future accesses by tailoring data movement to application semantics. Tapes-based mechanisms are layered on top of existing shared-memory protocols, and are largely independent of the underlying memory model. Tapes can also be used to emulate the data-movement semantics of several update-based protocol implementations, without altering the underlying protocol implementation. We have used tapes to create the Tapeworm synchronization library. Tapeworm implements sophisticated record-replay mechanisms across barriers, augments locks with data-movement semantics, and allows the use of producer-consumer segments, which move entire modified segments when any portion of the segment is accessed. We show that Tapeworm eliminates 85% of remote misses, reduces message traffic by 63%, and improves performance by an average of 29% for our application suite.
Medical Record Innovations That Can Improve Physician Productivity
Authors: Ralph R. Grams, Glen Morgan
Venue: Journal of Medical Systems (1999)

Medical records are the fulcrum of patient care activities. They represent the primary reference point with respect to the patient's medical status and long-term planning. A significant portion of the patient care dollar is invested in the medical record document and its handling. The most critical part of this process takes place in the physician's examination room during the patient encounter. The use of SmartCharts4 is a way to expedite the chart generation process and improve the quality and consistency of the source information from which all future care and plans are generated. The process removes a substantial portion of the human memory cycle that is needed for chart development and improves the encounter process by exploring the full range of diagnostic signs and symptoms that are associated with a preselected diagnosis or patient problem. The system is designed for stand-alone operation or insertion into an already-functioning electronic medical record system.
Micro-compression: a novel technique for the nondestructive assessment of local bone failure
Authors: R. Müller, S. C. Gerber, W. C. Hayes
Venue: Technology and Health Care (1998)

Many bones within the axial and appendicular skeleton are subjected to repetitive, cyclic loading during the course of ordinary daily activities. If this repetitive loading is of sufficient magnitude or duration, fatigue failure of the bone tissue may result. In clinical orthopedics, trabecular fatigue fractures are observed as compressive stress fractures in the proximal femur, vertebrae, calcaneus and tibia, and are often preceded by buckling and bending of microstructural elements. However, the relative importance of bone density and architecture in the etiology of these fractures is poorly understood. The aim of the study was to investigate failure mechanisms of 3D trabecular bone using micro-computed tomography (\muCT). Because of its nondestructive nature, \muCT represents an ideal approach for performing not only static measurements of bone architecture but also dynamic measurements of failure initiation and propagation as well as damage accumulation. For the purpose of the study, a novel micro-compression device was devised to measure loaded trabecular bone specimens directly in a micro-tomographic system. The measurement window in the device was made of a radiolucent, highly stiff plastic to enable X-rays to penetrate the material. The micro-compressor has an outer diameter of 19 mm and a total length of 65 mm. The internal load chamber fits wet or dry bone specimens with maximal diameters of 9 mm and maximal lengths of 22 mm. For the actual measurement, first, the unloaded bone is measured in the \muCT. Second, a load-displacement curve is recorded where the load is measured with an integrated mini-button load cell and the displacement is computed directly from the \muCT scout-view. For each load case, a 3D snap-shot of the structure under load is taken providing 34 \mum nominal resolution. Initial measurements included specimens from bovine tibiae and whale spine to investigate the influence of the structure type on the failure mechanism. In a rod-like type of architecture as seen in the whale spine, structural failure was described by an initial buckling and bending of structural elements followed by a collapse of the overloaded trabeculae. In the more plate-like bovine tibial architecture, buckling and bending could not be observed. Failure rather seemed to occur instantaneously. In conclusion, micro-compression in combination with 3D \muCT allows visualization of failure initiation and propagation and monitoring of damage accumulation in a nondestructive way. We expect these findings to improve our understanding of the relative importance of density, architecture and load in the etiology of spontaneous fractures of the hip and the spine. Eventually, this improved understanding may lead to more successful approaches to the prevention of age-related fractures.
javax.XXL: a prototype for a library of query processing algorithms
Authors: Jochen van den Bercken, Jens-Peter Dittrich, Bernhard Seeger
Venue: ACM SIGMOD Record (2000)

Therefore, index structures can easily be used in queries. A typical example is a join cursor which consumes the outputs of two underlying cursors. Most of our work is however not dedicated to the area of relational databases, but mainly refers to spatial and temporal data. For spatial databases, for example, we provide several implementations of spatial join algorithms [3]. The cursor-based processing is however the major advantage of XXL in contrast to approaches like LEDA [6] and TPIE [7]. For more information on XXL see http://www.mathematik.uni-marburg.de/DBS/xxl.We will demonstrate the latest version of XXL using examples to show its core functionality. We will concentrate on three key aspects of XXL.Usage: We show how easily state-of-the-art spatial join-algorithms can be implemented in XXL using data from different sources. Reuse: We will demonstrate how to support different joins, e.g. spatial and temporal joins, using the same generic algorithm like Plug Join [1].Comparability: We will demonstrate how XXL serves as an ideal testbed to compare query processing algorithms and index structures.
Human&mdash;machine load sharing in rehabilitation robotics
Authors: T. Rahman, K. McClenathan
Venue: Technology and Health Care (1999)

A force-assist mechanism has been developed to mount on the Chameleon - a wheelchair mounted rehabilitation robot. The device will amplify the forces applied by the user, making it possible to lift a large weight with a small force. This paper describes the test-bed development; instrumentation of the Chameleon with power assistance; and preliminary results on system efficacy.
Interoperability between the X.509 and EDIFACT public key infrastructures: the DEDICA project
Authors: M. Rubia, J. C. Cruellas, M. Medina, I. Callego
Venue: ACM SIGGROUP Bulletin (1998)

Over the last few years considerable effort has been dedicated to specifying and developing public key infrastructures (PKI's). Several initiatives from all around the world have resulted in the emergence of one PKI based on X.509 certificates and another based on EDIFACT certificates. Both PKIs include their own certificates and messages to simplify their management. However, these two PKIs are not interoperable, mainly because of the fact that the certificates and messages are coded differently (ASN.1 and DER are used for X.509 PKI, EDIFACT syntax for EDIFACT PKI).DEDICA (Directory based EDI Certificate Access and management) is a research and development project established by the European Commission under the Telematics Applications Program. The main objective of the DEDICA project is to define and provide a means of making these two infrastructures interoperable without increasing the amount of information that they handle. The proposed solution involves the design and implementation of a gateway tool interconnecting both PKIs. The main objective of this gateway is to translate certificates produced in one PKI to certificates produced in the other, maintaining as much as possible of the information present in the first. In this way, any user certified for instance within an X.509 PKI could get an EDIFACT certificate from this gateway without having to register in an EDIFACT infrastructure and use it to exchange EDIFACT messages with people certified within an EDIFACT PKI, who could also use their software to verity an EDIFACT certificate. The DEDICA gateway must therefore be capable of converting certain functionality of the UN/EDIFACT KEYMAN message (used for certification management) into access operations for the X.500 Distributed Directory, and vice versa. The gateway will in fact act as a proxy CA for the CAs of each PKI (it will sign the certificate resulting from the translation process). The tools developed for the gateway can also be used ill systems with a mixture of components. They can allow CAs in one of the PKIs to behave as CAs in the other. This gives a much wider scope to the work being done, as it can be the starting point for further specifications and developments leading to interoperability between other PKIs currently being developed (SPKI, for instance).
Copyright and technology innovation in higher education
Authors: Susan Ferencz Stager
Venue: ACM SIGUCCS Newsletter (1998)

Future Practical Management of Information Ethics Problems articles will focus upon intellectual property issues. This is an area where the boundary between the legal and ethical domains is both indistinct and rapidly changing. I am inviting legal experts to comment upon areas that are particularly relevant to higher education. Susan Ferencz Stager, former Director of Planning and Policy for Information Technology at Indiana University and current third-year Law student, provides insight into the tension between property protection and innovation in the following article. Her closing sentence should be taken as fair warning of a major ethical-legal issue your appropriate use policy needs to address.
Outcomes of Cataract Surgery: Implications for the Developing World
Authors: May Khadem
Venue: Journal of Medical Systems (1999)

Cataract surgery has virtually eliminated cataract blindness in the developed world. However, in the economically developing areas of the world it is a staggering and escalating problem where it is the leading cause of blindness affecting 16&ndash;20 million people. Outcomes research has clearly shown that modern cataract surgery with intraocular lens implantation is a safe and effective means of restoring visual function and improving vision-related quality of life. Several recent developments provide hope in the global fight against cataract blindness: decrease in the cost of modern surgery&semi; available models of infrastructure development&semi; and a global plan for the elimination of avoidable blindness.
Separating Maximally Violated Comb Inequalities in Planar Graphs
Authors: Søren Asmussen, Reuven Y. Rubinstein, L. Fleischer Fleischer, E. Tardos
Venue: Mathematics of Operations Research (1999)

The Traveling Salesman Problem (TSP) is a benchmark problem in combinatorial optimization. It was one of the very first problems used for developing and testing approaches to solving large integer programs, including cutting plane algorithms and branch-and-cut algorithms. Much of the research in this area has been focused on finding new classes of facets for the TSP polytope, and much less attention has been paid to algorithms for separating from these classes of facets. In this paper, we consider the problem of finding violated comb inequalities. If there are no violated subtour constraints in a fractional solution of the TSP, a comb inequality may not be violated by more than 1. Given a fractional solution in the subtour elimination polytope whose graph is planar, we either find a violated comb inequality or determine that there are no comb inequalities violated by 1. Our algorithm runs in O(n + MC(n)) time, where MC(n) is the time to compute a cactus representation of all minimum cuts of a weighted planar graph on n vertices.
Modeling and simulation of an ATM backbone network
Authors: Saad O. Alkasabi, Yasser M. AL-Eissa
Venue: International Journal of Network Management (2000)

We present a simulation model to analyze the performance of a Mesh ATM backbone network: using the proposed model, we study the performance of a fully connected network topology. Then we assess the impact of different routing schemes on network performance. Copyright &copy; 2000 John Wiley Sons, Ltd.
Low-power task scheduling for multiple devices
Authors: Yung-Hsiang Lu, Luca Benini, Giovanni De Micheli
Venue: Proceedings of the eighth international workshop on Hardware/software codesign (2000)

Power management saves power by shutting down idle devices. These devices often serve requests from concurrently running tasks. Ordering task execution can adjust the lengths of idle periods and exploit better opportunities for power management. This paper presents an on-line low-power scheduling algorithm for multiple devices. Simulations show that it can save up to 33% power and reduce 40% state-transition delays. This algorithm is robust under imperfect knowledge of future requests and timing constraints; therefore, it is applicable to interactive systems.
Automatic title generation for EM
Authors: Paul E. Kennedy, Alexander G. Hauptmann
Venue: Proceedings of the fifth ACM conference on Digital libraries (2000)

Our prototype automatic title generation system inspired by statistical machine-translation approaches [1] treats the document title like a translation of the document. Titles can be generated without extracting words from the document. A large corpus of documents with human-assigned titles is required for training title "translation" models. On an f1 evaluation score our approach outperformed another approach based on Bayesian probability estimates [7].
Query containment for data integration systems
Authors: Todd Millstein, Alon Levy, Marc Friedman
Venue: Proceedings of the nineteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems (2000)

The problem of query containment is fundamental to many aspects of database systems, including query optimization, determining independence of queries from updates, and rewriting queries using views. In the data integration framework, however, the standard notion of query containment does not suffice. We define relative containment, which formalizes the notion of query containment relative to the sources available to the integration system. First we provide optimal bounds for relative containment for several important classes of datalog queries, including the common case of conjunctive queries. Next we provide bounds for the case when sources enforce access restrictions in the form of binding pattern constraints. Surprisingly, we show that relative containment for conjunctive queries is still decidable in this case, even though it is known that finding all answers to such queries may require a recursive datalog program over the sources. Finally, we provide tight bounds for variants of relative containment when the queries and source descriptions may contain comparison predicates.
Realization of Multidimensional Digital Transfer Functionswith Separable Numerator or Denominator Polynomials
Authors: T. Venkateswarlu, C. Eswaran
Venue: Multidimensional Systems and Signal Processing (1999)

In this paper a straightforward z-domain procedure for realizing multidimensional transfer functions with either numerator or denominator polynomial separable is presented. This procedure yields structures with minimum number of multipliers. It is shown that the number of delay elements can be reduced by selecting the optimum values for certain parameters. To facilitate this theorems that are applicable for some special cases are presented.
Can Web development courses avoid obsolescence?
Authors: Frank Klassner
Venue: ACM SIGCSE Bulletin (2000)

Yes.