ppxscal/embedding_network huggingface dataset:
Finding generalized projected clusters in high dimensional spaces
Authors: Charu C. Aggarwal, Philip S. Yu
Venue: ACM SIGMOD Record (2000)

High dimensional data has always been a challenge for clustering algorithms because of the inherent sparsity of the points. Recent research results indicate that in high dimensional data, even the concept of proximity or clustering may not be meaningful. We discuss very general techniques for projected clustering which are able to construct clusters in arbitrarily aligned subspaces of lower dimensionality. The subspaces are specific to the clusters themselves. This definition is substantially more general and realistic than currently available techniques which limit the method to only projections from the original set of attributes. The generalized projected clustering technique may also be viewed as a way of trying to redefine clustering for high dimensional applications by searching for hidden subspaces with clusters which are created by inter-attribute correlations. We provide a new concept of using extended cluster feature vectors in order to make the algorithm scalable for very large databases. The running time and space requirements of the algorithm are adjustable, and are likely ta tradeoff with better accuracy.
Efficient and extensible algorithms for multi query optimization
Authors: Prasan Roy, S. Seshadri, S. Sudarshan, Siddhesh Bhobe
Venue: ACM SIGMOD Record (2000)

Complex queries are becoming commonplace, with the growing use of decision support systems. These complex queries often have a lot of common sub-expressions, either within a single query, or across multiple such queries run as a batch. Multiquery optimization aims at exploiting common sub-expressions to reduce evaluation cost. Multi-query optimization has hither-to been viewed as impractical, since earlier algorithms were exhaustive, and explore a doubly exponential search space. In this paper we demonstrate that multi-query optimization using heuristics is practical, and provides significant benefits. We propose three cost-based heuristic algorithms: Volcano-SH and Volcano-RU, which are based on simple modifications to the Volcano search strategy, and a greedy heuristic. Our greedy heuristic incorporates novel optimizations that improve efficiency greatly. Our algorithms are designed to be easily added to existing optimizers. We present a performance study comparing the algorithms, using workloads consisting of queries from the TPC-D benchmark. The study shows that our algorithms provide significant benefits over traditional optimization, at a very acceptable overhead in optimization time.
Optimizing existential datalog queries
Authors: Raghu Ramakrishnan, Catriel Beeri, Ravi Krishnamurthy
Venue: Proceedings of the seventh ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1988)

The problem of pushing projections in recursive rules has received little attention. The objective of this paper is to motivate this problem and present some (partial) solutions. We consider programs with function-free rules, also known as Datalog programs. After formally defining existential subqueries, we present a syntactic criterion for detecting them and then consider optimization in three areas 1) We identify the existential subqueries and make them explicit by rewriting the rules. This, in effect, automatically captures some aspects of Prolog's cut operator that are appropriate to the bottom-up model of computation 2) We eliminate argument positions in recursive rules by &ldquo;pushing projections&rdquo; 3) We observe that &ldquo;pushing projections&rdquo; in rules also has the effect of making some rules (even recursive rules) redundant and try to (identify and) discard them
The high level architecture and beyond: technology challenges
Authors: Judith S. Dahmann
Venue: Proceedings of the thirteenth workshop on Parallel and distributed simulation (1999)

The High Level Architecture (HLA) provides the specification of a software architecture for distributed simulation. The baseline definition of the HLA includes the HLA Rules, The HLA Interface Specification, and the HLA Object Model Template. The HLA Rules are a set of 10 basic rules that define the responsibilities and relationships among the components of an HLA federation. The HLA Interface Specification provides a specification of the functional interfaces between HLA federates and the HLA Runtime Infrastructure. The HLA OMT provides a common presentation format for HLA Simulation and Federation Object Models.The HLA was developed over the past three years. It is currently in the process of being applied with simulations developed for analysis, training and test and evaluation and incorporated into industry standards for distributed simulation by both the Object Management Group and the IEEE. This paper provides a discussion of key areas where there are technology challenges in the future implementation and application of the HLA.
Robust Optical Flow Computation Based on Least-Median-of-Squares Regression
Authors: E. P. Ong, M. Spann
Venue: International Journal of Computer Vision (1999)

An optical flow estimation technique is presented which is based on the least-median-of-squares (LMedS) robust regression algorithm enabling more accurate flow estimates to be computed in the vicinity of motion discontinuities. The flow is computed in a blockwise fashion using an affine model. Through the use of overlapping blocks coupled with a block shifting strategy, redundancy is introduced into the computation of the flow. This eliminates blocking effects common in most other techniques based on blockwise processing and also allows flow to be accurately computed in regions containing three distinct motions.A multiresolution version of the technique is also presented, again based on LMedS regression, which enables image sequences containing large motions to be effectively handled.An extensive set of quantitative comparisons with a wide range of previously published methods are carried out using synthetic, realistic (computer generated images of natural scenes with known flow) and natural images. Both angular and absolute flow errors are calculated for those sequences with known optical flow. Displaced frame difference error, used extensively in video compression, is used for those natural scenes with unknown flow. In all of the sequences tested, a comparison with those methods that result in a dense flow field (greater than 80% spatial coverage), show that the LMedS technique produces the least error irrespective of the error measure used.
DPLab: an environment for distributed programming
Authors: Mordechai Ben-Ari, Shawn Silverman
Venue: ACM SIGCSE Bulletin (1999)

This paper describes the software package DPLab which implements an integrated GUI environment for developing distributed programs. The environment includes a text editor, a compiler, and a runtime system that establishes communications between networked computers and provides primitives for message passing between the computers. The source language is Pascal extended with these primitives and with constructs for concurrent programming. The package is implemented in Java and Swing for portability.
On Isoperimetric Connectivity in Vertex-Transitive Graphs
Authors: Y. O. Hamidoune, A. S. Lladó, O. Serra, R. Tindell
Venue: SIAM Journal on Discrete Mathematics (2000)

We shall define the $k$-isoperimetric connectivity $\lambda _k$ of a regular graph $\Gamma $ as the minimum number of arcs originating in a set with cardinality not exceeding half the order of the graph and containing at least $k$ vertices. Clearly $\lambda _k \leq dk-e_k$, where $d$ is the degree of $\Gamma$ and $e_k$ is the maximal number of edges induced on a set of $k$ vertices. We shall show that Cayley graphs with a prime order and arc-transitive graphs have $\lambda _k =dk-e_k$, provided that $d\geq 3k-3$. We describe all vertex-transitive graphs where $\lambda _2\leq 2d-3$.
Distributed Route Selection for Establishing Real-Time Channels
Authors: Kang G. Shin, Chih-Che Chou, Seok-Kyu Kweon
Venue: IEEE Transactions on Parallel and Distributed Systems (2000)

To guarantee the delivery of real-time messages before their deadline, a real-time channel or connection must be established before the transmission of any message belonging to the connection. During this channel establishment phase, one must first select a route between the source and destination of this channel and then reserve sufficient resources along this route so that the worst-case end-to-end delay over the selected route may not exceed the user-specified delay bound. We propose an efficient distributed route selection scheme that is guaranteed to find a ¿qualified¿ route, if any, satisfying the performance requirement of the requested channel without compromising any of the existing guarantees. The proposed scheme can also eliminate the common reliability/performance bottleneck of a centralized route selection scheme while improving efficiency over the centralized and other distributed schemes. Although the proposed solution starts with searching all possible routes in parallel, it prunes infeasible routes quickly, and its worst-case operational overhead is shown to be only a linear function of the number of links in the network. Several examples and simulation results are presented to demonstrate the effectiveness of the proposed distributed route selection scheme as compared to sequential route-search schemes.
On-the-Fly Model Checking Under Fairness that Exploits Symmetry
Authors: Viktor Gyuris, A. Prasad Sistla
Venue: Formal Methods in System Design (1999)

An on-the-fly algorithm for model checking under fairness is presented. The algorithm utilizes symmetry in the program to reduce the state space, and employs novel techniques that make the on-the-fly model checking feasible. The algorithm uses state symmetry and eliminates parallel edges in the reachability graph. Experimental results demonstrating dramatic reductions in both the running time and memory usage are presented.
Parameterized system design
Authors: Tony D. Givargis, Frank Vahid
Venue: Proceedings of the eighth international workshop on Hardware/software codesign (2000)

Continued growth in chip capacity has led to new methodologies stressing reuse, not only of pre-designed processing components, but even of entire pre-designed architectures. To be used across a variety of applications, such architectures must be heavily parameterized, so they can adapt to those applications' differing constraints by trading off power, performance and size. We describe several parameterized system design issues, and provide results showing how a single architecture with easily configurable parameters can support a wide range of tradeoffs.
The Lack of Influence of the Right-Hand Side on the Accuracy of Linear System Solution
Authors: J. M. Banoczi, Nan-Chieh Chiu, Grace E. Cho, Ilse C. F. Ipsen
Venue: SIAM Journal on Scientific Computing (1998)

It is commonly believed that a fortunate right-hand side b can significantly reduce the sensitivity of a system of linear equations Ax=b. We show, both theoretically and experimentally, that this is not true when the system is solved (in floating point arithmetic) with Gaussian elimination or the QR factorization: the error bounds essentially do not depend on b, and the error itself seems to depend only weakly on b. Our error bounds are exact (rather than first-order); they are tight; and they are stronger than the bound of Chan and Foulser.We also present computable lower and upper bounds for the relative error. The lower bound gives rise to a stopping criterion for iterative methods that is better than the relative residual. This is because the relative residual can be much larger, and it may be impossible to reduce it to a desired tolerance.
Pseudospectral Solution of the Two-Dimensional Navier--Stokes Equations in a Disk
Authors: D. J. Torres, E. A. Coutsias
Venue: SIAM Journal on Scientific Computing (1999)

An efficient and accurate algorithm for solving the two-dimensional (2D) incompressible Navier--Stokes equations on a disk with no-slip boundary conditions is described. The vorticity-stream function formulation of these equations is used, and spatially the vorticity and stream functions are expressed as Fourier--Chebyshev expansions. The Poisson and Helmholtz equations which arise from the implicit-explicit time marching scheme are solved as banded systems using a postconditioned spectral $\tau$-method. The polar coordinate singularity is handled by expanding fields radially over the entire diameter using a parity modified Chebyshev series and building partial regularity into the vorticity. The no-slip boundary condition is enforced by transferring one of the two boundary conditions imposed on the stream function onto the vorticity via a solvability constraint. Significant gains in run times were realized by parallelizing the code in message passage interface (MPI).
A new approach to the design and analysis of peer-to-peer mobile networks
Authors: Imrich Chlamtac, András Faragó
Venue: Wireless Networks (1999)

This paper introduces a new model and methodological approach for dealing with the probabilistic nature of mobile networks based on the theory of random graphs. Probabilistic dependence between the random links prevents the direct application of the theory of random graphs to communication networks. The new model, termed Random Network Model, generalizes conventional random graph models to allow for the inclusion of link dependencies in a mobile network. The new Random Network Model is obtained through the superposition of Kolmogorov complexity and random graph theory, making in this way random graph theory applicable to mobile networks. To the best of the authors' knowledge, it is the first application of random graphs to the field of mobile networks and a first general modeling framework for dealing with ad-hoc network mobility. The application of this methodology makes it possible to derive results with proven properties. The theory is demonstrated by addressing the issue of the establishment of a connected virtual backbone among mobile clusterheads in a peer-to-peer mobile wireless network. Using the Random Network Model, we show that it is possible to construct a randomized distributed algorithm which provides connectivity with high probability, requiring exponentially fewer connections (peer-to-peer logical links) per clusterhead than the number of connections needed for an algorithm with a worst case deterministic guarantee.
Process Variation As a Determinant of Bank Performance: Evidence From the Retail Banking Study
Authors: Frances X. Frei, Ravi Kalakota, Andrew J. Leone, Leslie M. Marx
Venue: Management Science (1999)

This paper explores the relation between retail banks' branch-based processes and financial performance. There are 11 processes included in this study, which represent the bulk of the activities performed in a typical retail branch (e.g., opening checking accounts). The first finding of this study is that the financial performance of banks that perform better across these processes tend to be better than that of other banks. In addition to the variation in process performance across banks, there is also substantial variation across processes within banks. That is, banks that performed well in one process often performed quite badly in another. We present an analytical model that shows that improvement in process variation can be more important than improvement in aggregate process performance when dealing with certain customer segments. Empirical evidence from the Wharton Financial Institution Center Retail Banking Study of bank holding companies in the United States provides support.
Location update and routing scheme for a mobile computing environment
Authors: Anna Hać, Yujing Huang
Venue: International Journal of Network Management (2000)

We present a new hierarchical location update and routing scheme for a wide area mobile computing environment with scalability of network hierarchy. Our scheme provides nearly optimal routing for most communication bypassing the mobile host&apos;s home network and home agent. We use simulation to compare our scheme with other schemes in both non&hyphen;hierarchical and hierarchical network architectures. Copyright &copy; 2000 John Wiley Sons, Ltd.
Frame Rate and Viseme Analysis for Multimedia Applications toAssist Speechreading
Authors: Jay J. Williams, Janet C. Rutledge, Aggelos K. Katsaggelos, Dean C. Garstecki
Venue: Journal of VLSI Signal Processing Systems (1998)

Current video conference and phone systems do not provide the necessary temporal resolution and motion for speechreading. In this paper the perceptual boundaries which effect speechreading performance are investigated. Analysis of the relationships between viseme groupings, accuracy of viseme recognition and presentation frame rate is presented based on the results of subject testing. Results reveal a minimum frame rate of 10 frames per second (fps) for distinguishing viseme groupings. Confusion analysis results demonstrate the importance of the tongue and teeth oral features for speechreading. These results are critical to the design of speech-assisted video systems to enhance speechreading for individuals with impaired hearing.
Flows in Undirected Unit Capacity Networks
Authors: Andrew V. Goldberg, Satish Rao
Venue: SIAM Journal on Discrete Mathematics (1999)

We describe an O(min(m,n3/2)m1/2)-time algorithm for finding maximum flows in undirected networks with unit capacities and no parallel edges. This improves upon the previous bound of Karzanov and Even and Tarjan when $m = \omega(n^{3/2})$, and upon a randomized bound of Karger when $v = \Omega(n^{7/4}/m^{1/2})$.
The facilitators perspective on meetings and implications for group support systems design
Authors: Stephen C. Hayne
Venue: ACM SIGMIS Database (1999)

Based on research into group process facilitation, a meeting model is proposed that defines the many activities comprising group work and highlights the critical facilitator actions. Facilitating group work is a dynamic process that involves managing relationships among people, tasks and technology, as well as structuring the interactions contributing to an effective meeting. By examining existing group support systems (GSS), it is shown that assistance for facilitation is low. With this information, methods are proposed to improve facilitation support (and therefore the meeting process) in GSS for face-to-face or dispersed environments.
Constructing, organizing, and visualizing collections of topically related Web resources
Authors: Loren Terveen, Will Hill, Brian Amento
Venue: ACM Transactions on Computer-Human Interaction (TOCHI) (1999)

For many purposes, the Web page is too small a unit of interaction and analysis. Web sites are structured multimedia documents consisting of many pages, and users often are interested in obtaining and evaluating entire collections of topically related sites. Once such a collection is obtained, users face the challenge of exploring, comprehending and organizing the items. We report four innovations that address these user needs: (1) we replaced the Web page with the Web site as the basic unit of interaction and analysis;(2) we defined a new informationstructure, the clan graph, that groups together sets of related sites; (3) we augment the representation of a site with a site profile, information about site structure and content that helps inform user evaluation of a site; and (4) we invented a new graph visualization, the auditorium visualization, that reveals important structural and content properties of sites within a clan graph. Detailed analysis and user studies document the utility of this approach. The clan graph construction algorithm tends to filter out irrelevant sites and discover additional relevant items. The auditorium visualization, augmented with drill-down capabilities to explore site profile data, helps users to find high-quality sites as well as sites that serve a particular function.
Importance of Convection and Damping on Rates of Convergence for the Lax--Wendroff Method
Authors: Joseph Kolibal
Venue: SIAM Journal on Scientific Computing (1999)

It is well known that in solving steady state problems using hyperbolic time-stepping methods the intent is to drive the transients to zero as quickly as possible. In this paper the convergence to steady state of the Lax--Wendroff method applied to solving the equations of gas dynamics is analyzed for the Laval nozzle problem by comparing the relative rates of damping and convection using a linearized eigenmode analysis. This analysis is developed for the simpler isenthalpic system and then extended to the full Euler equations. Finally, this allows a comparison between these systems. For both models, useful analytical information can be gleaned about the transient behavior of these systems, especially in regard to quantifying the competitive factors affecting the removal of unsteady waves.
A (2.954 + &epsilon;)n oblivious routing algorithm on 2D meshes
Authors: Kazuo Iwama, Eiji Miyano
Venue: Proceedings of the twelfth annual ACM symposium on Parallel algorithms and architectures (2000)

We present a deterministic, oblivious, permutation-routing algorithm on the n &times; n mesh of constant queue-size. It runs in (2.954+&egr;)n steps for any &egr; > 0. Previously, an O(n)-time algorithm was known but with no nontrivial upper bounds on the constant factor.
New Approach to the Medical Information System for Quality Management in Patient Care: Development of Problem Mapping System
Authors: Yoshiyasu Okuhara, Yasuhiro Kitazoe, Yuichi Narita, Yukio Kurihara, Kimio Matsuura, Toshiji Saibara, Saburo Onishi, Atsushi Kagiyama, Noriko Inaoka
Venue: Journal of Medical Systems (1999)

A new type of medical information system named Problem Mapping System (P-Map) has been developed, which aids physicians with solving patients' problems. With this system, physicians can define the problems of in-patients, monitor their progress clearly, and share information efficiently. In P-map, a list of problems, such as disease names, can be set for each inpatient easily. The progress of each problem is clearly shown using progress lines on a time axis. Physicians can save the Subjective Objective Assessment Plan (SOAP) notes which are linked to each problem. At the final stage of patient care, a discharge summary can be made easily. With the aid of this system, the quality of patient care is improved due to the following: (1) physicians can make the best decision&semi; (2) medical staff in the same team can provide the best medical treatment&semi; (3) evaluation of each medical treatment is easy&semi; (4) saved data can be used effectively for education and research&semi; (5) the system can improve cooperation with other medical institutes by providing discharge summary information which can be distributed using e-mail&semi; and (6) the system can improve patients' understanding for the purpose of informed consent by providing clear and well organized information to patients.
Synthesis for multiple input wires replacement of a gate for wiring consideration
Authors: Shih-Chieh Chang, Jung-Cheng Chuang, Zhong-Zhen Wu
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

The alternative wire technique attempts to replace a target wire by another wire without charging the logic functionality. In this paper, we propose two new transformations of replacing wires. One transformation simultaneously replaces multiple input wires of a gate by a new set of input wires and the other performs gate decompostion during the alternative wire process. To accomplish such complex transformations, we discuss some theoretical foundations for replacing multiple wires. Understanding how wires/gates can be replaced by other wires/gates allows us to speedup the process tremendously.