ppxscal/embedding_network huggingface dataset:
Density biased sampling: an improved method for data mining and clustering
Authors: Christopher R. Palmer, Christos Faloutsos
Venue: ACM SIGMOD Record (2000)

Data mining in large data sets often requires a sampling or summarization step to form an in-core representation of the data that can be processed more efficiently. Uniform random sampling is frequently used in practice and also frequently criticized because it will miss small clusters. Many natural phenomena are known to follow Zipf's distribution and the inability of uniform sampling to find small clusters is of practical concern. Density Biased Sampling is proposed to probabilistically under-sample dense regions and over-sample light regions. A weighted sample is used to preserve the densities of the original data. Density biased sampling naturally includes uniform sampling as a special case. A memory efficient algorithm is proposed that approximates density biased sampling using only a single scan of the data. We empirically evaluate density biased sampling using synthetic data sets that exhibit varying cluster size distributions finding up to a factor of six improvement over uniform sampling.
"Cool low power" 1GHz multi-port register file and dynamic latch in 1.8 V, 0.25 μm SOI and bulk technology (poster session)
Authors: R. V. Joshi, W. Hwang, S. C. Wilson, C. T. Chuang
Venue: Proceedings of the 2000 international symposium on Low power electronics and design (2000)

This paper describes power analysis at sub-zero temperatures for a high performance dynamic multiport register file (6 Read and 2 Write ports, 32 wordlines x 64 bitlines) fabricated in 0.25 &mgr;m Silicon on Insulator (SOI) and bulk technologies. Based on the hardware it is shown that the performance of both register file and latch improves by 2-3.5% per 10§ C reduction in temperature. The standby power for SOI reduces by 1.5% to 3 per 10§ C temperature drop down to -30§ C. The SOI chip is shown to have more significant performance improvement at low temperatures compared to bulk chip due to the floating body effect which partially offsets the increase in the threshold voltages (Vt). The low temperature performance gain is attributed to reduction in capacitance (around 7-8%) and rest is due to dynamic threshold voltages. At 30§ C the register file is capable of functioning close to 1.02 GHz for read and write operations in a single cycle.
A clustering- and probability-based approach for time-multiplexed FPGA partitioning
Authors: Mango Chia-Tso Chao, Guang-Ming Wu, Iris Hui-Ru Jiang, Yao-Wen Chang
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

Improving logic density by time-sharing, time-multiplexed FPGAs (TMFPGAs) have become an important research topic for reconfigurable computing. Due to the precedence and capacity constraints in TMFPGAs, the clustering and partitioning problems for TMFPGAs are different from the traditional ones. In this paper, we propose a two-phase hierarchical approach to solve the partitioning problem for TMFPGAs. With the precedence and capacity considerations for both phases, the first phase clusters nodes to reduce the problem size, and the second phase applies a probability-based iterative-improvement approach to minimize cut cost. Experimental results based on the Xilinx TMFPGA architecture show that our algorithm significantly outperforms previous works.
2D Model-Following Servo System
Authors: Minoru Yamada, Li Xu, Osami Saito
Venue: Multidimensional Systems and Signal Processing (1999)

This paper gives, in view of the feature of practical 2D (2-dimensional) systems, a formulation of the 2D model-following servo problem for the case where one of the independent variables of the considered 2D systems is unbounded and the other one is bounded. That is, to determine a control input such that the outputs of a given 2D plant asymptotically track, with tracking error as small as possible, the (step) response of a given 2D model system as the unbounded variable approaches infinite. It is shown that this problem under a specified quadratic performance index can be transformed into a 1D LQR problem, and thus can be solved by the well-known 1D approaches. The relation between the solvability condition obtained for the equivalent 1D LQR problem and the practical stabilizability and detectability of the original 2D plant is clarified. Its application to the design of non-unit memory linear multipass processes is also shown. Finally, a numerical example for metal rolling process is given to verify the effectiveness.
Developing a digital library of computer science teaching resources
Authors: Scott Grissom, Deborah Knox, Elana Copperman, Wanda Dann, Michael Goldweber, Janet Hartman, Marja Kuittinen, David Mutchler, Nick Parlante
Venue: ACM SIGCUE Outlook (1998)

We describe recommendations for how to plan and develop a web-based digital library to support computer science education, i.e., the online Computer Science Teaching Center (CSTC) lt;www.cstc.org/~cstc gt;. This report details three facets: the identification of appropriate resources for inclusion in the CSTC, the review process for submissions, and the development and promotion of CSTC. A taxonomy of teaching resources is provided, and includes informal feedback from ITiCSE '98 conference participants enumerating desirable materials. Categories recommended for inclusion are: Labware / Courseware, Presentation / Exposition, On-line Course, Small Assignment, and Large Assignment. A formal review process is defined and detailed in order to insure that high quality materials are contained in the CSTC. A core set of reviewer guidelines is presented, suitable for the resources identified. Finally, recommendations for the marketing and the mechanics of the site are presented. The CSTC initially will support materials of visualizations, laboratory projects, and NSF CISE Education Innovation projects. Strong association with professional organizations, such as ACM and IEEE, is recommended. The working group unanimously recommends that access to CSTC resources should remain free of charge, to serve the widest possible audience.
ASPEN: A Microsimulation Model of the Economy
Authors: N. Basu, R. Pryor, T. Quint
Venue: Computational Economics (1998)

In this report we present ASPEN, a new agent-based microeconomic simulation model of the U.S. economy being developed at Sandia National Laboratories (SNL). The model is notable because it allows a large number of individual economic agents to be modeled at a high level of detail and with a great degree of freedom. Some of the features of ASPEN are (a) a sophisticated message-passing system which allows individual pairs of agents to communicate with one another, (b) the use of genetic algorithms to simulate certain agents&lsquo; learning, and (c) a detailed financial sector which includes a banking system and a bond market. Results from runs of the model are also presented.
A Fast Recursive Algorithm for Constructing Matrices with Prescribed Eigenvalues and Singular Values
Authors: Moody T. Chu
Venue: SIAM Journal on Numerical Analysis (2000)

The Weyl--Horn theorem characterizes a relationship between the eigenvalues and the singular values of an arbitrary matrix. Based on that characterization, a fast recursive algorithm is developed to construct numerically a matrix with prescribed eigenvalues and singular values. Besides being of theoretical interest, the technique could be employed to create test matrices with desired spectral features. Numerical experiment shows this algorithm to be quite efficient and robust.
Inequalities for Unitarily Invariant Norms
Authors: Xingzhi Zhan
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

Let A,B,X be complex matrices with A,B positive semidefinite. It is proved that (2+t)||ArXB2-r+A2-rXBr||\le 2||A2X+tAXB+XB2|| for any unitarily invariant norm $||\cdot||$ and real numbers r,t satisfying $1\le 2r\le 3,$ $-2 r=1, t=0$ of this result is the well-known arithmetic-geometric mean inequality due to R. Bhatia and C. Davis [SIAM J. Matrix Anal. Appl., 14 (1993), pp. 132--136]. Several other unitarily invariant norm inequalities are derived.
Positivity of Block Tridiagonal Matrices
Authors: Martin Bohner, Ondrej Doslý
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

This paper relates disconjugacy of linear Hamiltonian difference systems (LHdS) (and hence positive definiteness of certain discrete quadratic functionals) to positive definiteness of some block tridiagonal matrices associated with these systems and functionals. As a special case of a Hamiltonian system, Sturm--Liouville difference equations are considered, and analogous results are obtained for these important objects.
Second Order Hamilton--Jacobi Equations in Hilbert Spaces and Stochastic Boundary Control
Authors: Fausto Gozzi, Elisabeth Rouy, Andrzej Swiech
Venue: SIAM Journal on Control and Optimization (2000)

The paper is concerned with fully nonlinear second order Hamilton--Jacobi--Bellman--Isaacs equations of elliptic type in separable Hilbert spaces which have unbounded first and second order terms. The viscosity solution approach is adapted to the equations under consideration and the existence and uniqueness of viscosity solutions are proved. A stochastic optimal control problem driven by a parabolic stochastic PDE with control of Dirichlet type on the boundary is considered. It is proved that the value function of this problem is the unique viscosity solution of the associated Hamilton--Jacobi--Bellman equation.
Dragonfly: linking conceptual and implementation architectures of multiuser interactive systems
Authors: Gary E. Anderson, T. C. Nicholas Graham, Timothy N. Wright
Venue: Proceedings of the 22nd international conference on Software engineering (2000)

Software architecture styles for developing multiuser applications are usually defined at a conceptual level, abstracting such low-level issues of distributed implementation as code replication, caching strategies and concurrency control policies. Ultimately, such conceptual architectures must be cast into code. The iterative design inherent in interactive systems implies that significant evolution will take place at the conceptual level. Equally, however, evolution occurs at the implementation level in order to tune performance. This paper introduces Dragonfly, a software architecture style that maintains a tight, bidirectional link between conceptual and implementation software architectures, allowing evolution to be performed at either level. Dragonfly has been implemented in the Java-based TeleComputing Developer (TCD) toolkit.
Internet environment and outsourcing
Authors: Dan Salenger
Venue: International Journal of Network Management (1997)

This article discusses the issue of internet security from a business perspective. It describes strategies that relate to the needs of different types of business, and covers both outsourced and in-house systems. &copy; 1997 John Wiley & Sons, Ltd.
Ranking Primitive Recursions: The Low Grzegorczyk Classes Revisited
Authors: Stephen J. Bellantoni, Karl-Heinz Niggl
Venue: SIAM Journal on Computing (1999)

Traditional results in subrecursion theory are integrated with the recent work in "predicative recursion" by defining a simple ranking $\rho$ of all primitive recursive functions. The hierarchy defined by this ranking coincides with the Grzegorczyk hierarchy at and above the linear-space level. Thus, the result is like an extension of the Schwichtenberg--Müller theorems. When primitive recursion is replaced by recursion on notation, the same series of classes is obtained except with the polynomial time computable functions at the first level.
Math link: linking curriculum, instructional strategies, and technology to enhance teaching and learning
Authors: Harriet G. Taylor
Venue: ACM SIGCSE Bulletin (1999)

Math Link was a professional development project involving Louisiana State University and the West Feliciana Parish School District in the United States. Math Link focused on teachers in grades three through six in the entire district and included over ninety percent of the teachers in the district. The teachers participated in a three week summer workshop directed by a professional staff that included two elementary mathematics specialists, a technology specialist, a mathematics specialist/site coordinator from the school district, a mathematics education professor, and an educational technology professor.During the summer, the educators worked on four major components: technology tools to support learning: mathematics standards, instructional methodology, and assessment; team building and collaboration; and instructional models that they would implement. During the academic year, a site coordinator provided instructional and resource support for all the teachers. The site coordinator also monitored progress and worked directly with the university staff directing the project. Four day-long workshops were also held during the school year. During the following summer, the educators worked at the university for two more weeks to formalize their instructional models and curriculum and plan for the future.
Finding an Even Simple Path in a Directed Planar Graph
Authors: Zhivko Prodanov Nedev
Venue: SIAM Journal on Computing (1999)

In this paper we show that the following problem, the even simple path (ESP) problem for directed planar graphs, is solvable in polynomial time:Given: a directed planar graph G=(V,E) and two nodes s, (starting node), t ,(targetnode) \in V; Find: a simple path (i.e., without repeated nodes) from s to t of even length. (The length of the path is the number of edges it contains.)
Active database systems
Authors: Norman W. Paton, Oscar Díaz
Venue: ACM Computing Surveys (CSUR) (1999)

Active database systems support mechanisms that enable them to respond automatically to events that are taking place either inside or outside the database system itself. Considerable effort has been directed towards improving understanding of such systems in recent years, and many different proposals have been made and applications suggested. This high level of activity has not yielded a single agreed-upon standard approach to the integration of active functionality with conventional database systems, but has led to improved understanding of active behavior description languages, execution models, and architectures. This survey presents the fundamental characteristics of active database systems, describes a collection of representative systems within a common framework, considers the consequences for implementations of certain design decisions, and discusses tools for developing active applications.
View-based query processing for regular path queries with inverse
Authors: Diego Calvanese, Moshe Y. Vardi, Giuseppe de Giacomo, Maurizio Lenzerini
Venue: Proceedings of the nineteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems (2000)

View-based query processing is the problem of computing the answer to a query based on a set of materialized views, rather than on the raw data in the database. The problem comes in two different forms, called query rewriting and query answering, respectively. In the first form, we are given a query and a set of view definitions, and the goal is to reformulate the query into an expression that refers only to the views. In the second form, besides the query and the view definitions, we are also given the extensions of the views and a tuple, and the goal is to check whether the knowledge on the view extensions logically implies that the tuple satisfies the query.In this paper we address the problem of view-based query processing in the context of semistructured data, in particular for the case of regular-path queries extended with the inverse operator. Several authors point out that the inverse operator is one of the fundamental extensions for making regular-path queries useful in real settings. We present a novel technique based on the use of two-way finite-state automata. Our approach demonstrates the power of this kind of automata in dealing with the inverse operator, allowing us to show that both query rewriting and query answering with the inverse operator has the same computational complexity as for the case of standard regular-path queries.
Record-boundary discovery in Web documents
Authors: D. W. Embley, Y. Jiang, Y.-K. Ng
Venue: Proceedings of the 1999 ACM SIGMOD international conference on Management of data (1999)

Extraction of information from unstructured or semistructured Web documents often requires a recognition and delimitation of records. (By &ldquo;record&rdquo; we mean a group of information relevant to some entity.) Without first chunking documents that contain multiple records according to record boundaries, extraction of record information will not likely succeed. In this paper we describe a heuristic approach to discovering record boundaries in Web documents. In our approach, we capture the structure of a document as a tree of nested HTML tags, locate the subtree containing the records of interest, identify candidate separator tags within the subtree using five independent heuristics, and select a consensus separator tag based on a combined heuristic. Our approach is fast (runs linearly for practical cases within the context of the larger data-extraction problem) and accurate (100% in the experiments we conducted).
Ada as a teaching language
Authors: SY Wong
Venue: ACM SIGAda Ada Letters (1999)

There is a need for a single, simple language suitable both for teaching the important fundamentals of programming and for practical applications long after graduation.
On-line reorganization in object databases
Authors: Mohana K. Lakhamraju, Rajeev Rastogi, S. Seshadri, S. Sudarshan
Venue: ACM SIGMOD Record (2000)

Reorganization of objects in an object databases is an important component of several operations like compaction, clustering, and schema evolution. The high availability requirements (24 &times; 7 operation) of certain application domains requires reorganization to be performed on-line with minimal interference to concurrently executing transactions. In this paper, we address the problem of on-line reorganization in object databases, where a set of objects have to be migrated from one location to another. Specifically, we consider the case where objects in the database may contain physical references to other objects. Relocating an object in this case involves finding the set of objects (parents) that refer to it, and modifying the references in each parent. We propose an algorithm called the Incremental Reorganization Algorithm (IRA) that achieves the above task with minimal interference to concurrently executing transactions. The IRA algorithm holds locks on at most two distinct objects at any point of time. We have implemented IRA on Brahma, a storage manager developed at IIT Bombay, and conducted an extensive performance study. Our experiments reveal that IRA makes on-line reorganization feasible, with very little impact on the response times of concurrently executing transactions and on overall system throughput. We also describe how the IRA algorithm can handle system failures.
A Time-Space Tradeoff for Undirected Graph Traversal by Walking Automata
Authors: Paul Beame, Allan Borodin, Prabhakar Raghavan, Walter L. Ruzzo, Martin Tompa
Venue: SIAM Journal on Computing (1999)

We prove a time-space tradeoff for traversing undirected graphs, using a structured model that is a nonjumping variant of Cook and Rackoff's "jumping automata for graphs."
Is osteoporosis a matter of over-adaptation?
Authors: Harrie Weinans
Venue: Technology and Health Care (1998)

The stiffness and strength of cancellous bone depends on the amount of bone mineral (BMD) and on the three-dimensional distribution of the mineral (architecture). The relationship between mechanical properties and architecture, excluding confounding effects due to BMD can be studied using computer models of cancellous bone. It was shown that adaptation to mechanical deformation energy leads to an architecture which is an optimal or semi-optimal configuration with respect to maximal stiffness and minimal mass. Thus, the stiffness of the cancellous bone relative to the amount of bone (the bone density) can be considered as an optimality criterion. Based on these findings we assumed that the status of osteoporosis - or better fracture risk - could be related to how close this optimality criterion was met. In other words, we assumed that a higher fracture risk is simply related to a less optimal structure. This was tested for cancellous bone samples taken from post mortem vertebral bodies from two groups of subjects: one group with high fracture incidence during their lives and one group of healthy controls. It was found that the specimen from the high fracture incidence group had an architecture leading to a slightly stiffer structure relative to the BMD value. The conclusion is therefore that vertebral bone specimen from subjects with high fracture incidence are better optimized which was contradictory to what we expected. This finding indicates that bone specimen from the healthy control subjects had bone matrix at locations which are relatively unloaded. This tissue can be considered as not mechanically efficient or functional. A possible explanation of the present findings is that bone from subjects with increased fracture incidence is better adapted to mechanical stress, because it needs all bone material to carry the load. This stronger adaptation might be related to a compromised safety factor against bone loss, or diminished intrinsic matrix properties (e.g., microdamage).
Performance analysis of centralized FH-CDMA wireless networks
Authors: Khairi Ashour Mohamed, László Pap
Venue: Wireless Networks (1999)

Centralized CDMA networks with unslotted Aloha random-access mode are considered. Users communicate with a central node by sharing a finite number of signature sequences assigned to the receivers at the central node. Two methods for sharing preamble codes are considered. In one method a common preamble code is used by all receivers, and in the other method a distinct code is assigned for each receiver. A unified analysis framework for evaluating the performance of centralized FH-CDMA networks is developed. Closed form expressions for packet decoding error probabilities are derived. Numerical results show that common preamble codes can support only low traffic levels. However, by appropriately selecting the design parameters, acceptable levels of packet loss probabilities are achievable with the receiver-based preambles.
The block-based trace cache
Authors: Bryan Black, Bohuslav Rychlik, John Paul Shen
Venue: Proceedings of the 26th annual international symposium on Computer architecture (1999)

The trace cache is a recently proposed solution to achieving high instruction fetch bandwidth by buffering and reusing dynamic instruction traces. This work presents a new block-based trace cache implementation that can achieve higher IPC performance with more efficient storage of traces. Instead of explicitly storing instructions of a trace, pointers to blocks constituting a trace are stored in a much smaller trace table. The block-based trace cache renames fetch addresses at the basic block level and stores aligned blocks in a block cache. Traces are constructed by accessing the replicated block cache using block pointers from the trace table. Performance potential of the block-based trace cache is quantified and compared with perfect branch prediction and perfect fetch schemes. Comparing to the conventional trace cache, the block-based design can achieve higher IPC, with less impact on cycle time.Results: Using the SPECint95 benchmarks, a 16-wide realistic design of a block-based trace cache can improve performance 75% over a baseline design and to within 7% of a baseline design with perfect branch prediction. With idealized trace prediction, it is shown the block-based trace cache with an 1K-entry block cache achieves the same performance of the conventional trace cache with 32K entries.