ppxscal/embedding_network huggingface dataset:
Perturbation Analysis of the Cholesky Downdating and QR Updating Problems
Authors: Ji-Guang Sun
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

Given upper triangular matrices $R, G$ and column vectors $x, f$ such that $R^{T}R-xx^T$ and $(R+G)^{T}(R+G)-(x+f)(x+f)^T$ are positive definite, let $U$ and $U+T$ be the corresponding Cholesky factors. In this paper, upper bounds on $\|T\|$ in terms of $\|G\|$ and $\|f\|$ and upper bounds on $\|T\|/\|U\|$ in terms of $\|G\|/\|R\|$ and $\|f\|/\|x\|$ are given, and the first order perturbation expansions of $\|T\|$ and $\|T\|/\|U\|$ are derived. Moreover, a perturbation analysis of the QR updating problem is also given.
Floor acquisition multiple access (FAMA) for packet-radio networks
Authors: Chane L. Fullmer, J. J. Garcia-Luna-Aceves
Venue: Proceedings of the conference on Applications, technologies, architectures, and protocols for computer communication (1995)

A family of medium access control protocols for single-channel packet radio networks is specified and analyzed. These protocols are based on a new channel access discipline called floor acquisition multiple access (FAMA), which consists of both carrier sensing and a collision-avoidance dialogue between a source and the intended receiver of a packet. Control of the channel (the floor) is assigned to at most one station in the network at any given time, and this station is guaranteed to be able to transmit one or more data packets to different destinations with no collision with transmissions from other stations. The minimum length needed in control packets to acquire the floor is specified as a function of the channel propagation time. The medium access collision avoidance (MACA) protocol proposed by Karn and variants of CSMA based on collision avoidance are shown to be variants of FAMA protocols when control packets last long enough compared to the channel propagation delay. The throughput of FAMA protocols is analyzed and compared with the throughput of non-persistent CSMA. This analysis shows that using carrier sensing as an integral part of the floor acquisition strategy provides the benefits of MACA in the presence of hidden terminals, and can provide a throughput comparable to, or better than, that of non-persistent CSMA when no hidden terminals exist.
Scheduling Parallel Machines On-line
Authors: David B. Shmoys, Joel Wein, David P. Williamson
Venue: SIAM Journal on Computing (1995)

The problem of scheduling jobs on parallel machines is studied when (1) the existence of a job is not known until its unknown release date and (2) the processing requirement of a job is not known until the job is processed to completion. Two general algorithmic techniques are demonstrated for converting existing polynomial-time algorithms that require complete knowledge about the input data into algorithms that need less advance knowledge. Information-theoretic lower bounds on the length of on-line schedules are proven for several basic parallel machine models, and that almost all of our algorithms construct schedules with lengths that either match or come within a constant factor of the lower bound.
An efficient and fast parallel-connected component algorithm
Authors: Yujie Han, Robert A. Wagner
Venue: Journal of the ACM (JACM) (1990)

A parallel algorithm for computing the connected components of undirected graphs is presented. Shared memory computation models are assumed. For a graph of e edges and n nodes, the time complexity of the algorithm is &Ogr;(e/p + (n log n)/p + log2n) with p processors. The algorithm can be further refined to yield time complexity &Ogr;(H(e, n, p)/p + (n log n)/(p log(n/p)) + log2n), where H(e, n, p) is very close to &Ogr;(e). These results show that linear speedup can be obtained for up to p &le; e/log2n processors when e &ge; n log n. Linear speedup can still be achieved with up to p &le; n&egr; processors, 0 &le; &egr; < 1, for graphs satisfying e &ge; n log(*)n. Our results can be further improved if a more efficient integer sorting algorithm is available.
A critique of ANSI SQL isolation levels
Authors: Hal Berenson, Phil Bernstein, Jim Gray, Jim Melton, Elizabeth O'Neil
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

ANSI SQL-92 [MS, ANSI] defines Isolation Levels in terms of phenomena: Dirty Reads, Non-Repeatable Reads, and Phantoms. This paper shows that these phenomena and the ANSI SQL definitions fail to properly characterize several popular isolation levels, including the standard locking implementations of the levels covered. Ambiguity in the statement of the phenomena is investigated and a more formal statement is arrived at; in addition new phenomena that better characterize isolation types are introduced. Finally, an important multiversion isolation type, called Snapshot Isolation, is defined.
Greedy Packet Scheduling
Authors: Israel Cidon, Shay Kutten, Yishay Mansour, David Peleg
Venue: SIAM Journal on Computing (1995)

Scheduling packets to be forwarded over a link is an important subtask of the routing process in both parallel computing and in communication networks. This paper investigates the simple class of greedy scheduling algorithms, namely, algorithms that always forward a packet if they can. It is first proved that for various "natural" classes of routes, the time required to complete the transmission of a set of packets is bounded by the number of packets, $k$, and the maximal route length, $d$, for any greedy algorithm (including the arbitrary scheduling policy). Next, tight time bounds of $d+k-1$ are proved for a specific greedy algorithm on the class of shortest paths in $n$-vertex networks. Finally, it is shown that when the routes are arbitrary, the time achieved by various "natural" greedy algorithms can be as bad as $\Omega(d \sqrt{k} + k)$, for any $k$, and even for $d=\Omega(n)$.
VisDB: a system for visualizing large databases
Authors: Daniel A. Keim, Hans-Peter Kriegel
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

The VisDB system developed at the University of Munich is a sophisticated tool for visualizing and analyzing large databases. The key idea of the VisDB system is to support the exploration of large databases by using the phenomenal abilities of the human vision system which is able to analyze visualizations of mid-size to large amounts of data very efficiently. The goal of the VisDB system is to provide visualizations of large portions of the database, allowing properties of the data and structure in the data to become perceptually apparent.
Optimizing sparse representations for dataflow analysis
Authors: Erik Ruf
Venue: ACM SIGPLAN Notices (1995)

Sparse program representations allow inter-statement dependences to be represented explicitly, enabling dataflow analyzers to restrict the propagation of information to paths where it could potentially affect the dataflow solution. This paper describes the use of a single sparse program representation, the value dependence graph, in both general and analysis-specific contexts, and demonstrates its utility in reducing the cost of dataflow analysis. We find that several semantics-preserving transformations are beneficial in both contexts.
Set management: minimizing synchronization delays of prefabricated parts before assembly
Authors: Manfred Mittler, Michael Purm, Ottmar Gihr
Venue: Proceedings of the 27th conference on Winter simulation (1995)

The paper addresses the problem of synchronizing prefabricated parts for assembly into modules. We examine production environments arising out of semiconductor manufacturing and multi layer ceramics where several prefabricated parts, so-called sets, are necessary to complete a module. Frequently, some of these components are manufactured by the same production system. In order to minimize the inventory of the entire production system and simultaneously to achieve short cycle times, we propose sophisticated sequencing rules (named set management policies) to control the production of components. Based on global status information on the inventory at each service station these policies determine the component which is to be processed next. We evaluate the performance of the set management policies proposed, by means of simulation results for several production environments which feature rework and re-entrant flow. In terms of several performance measures we show that our sequencing rules achieve better results than standard rules such as FCFS of EDD. The mean of the performance measures and also their variances are considered.
Functional back-ends within the lambda-sigma calculus
Authors: Thérèse Hardin, Luc Maranget, Bruno Pagano
Venue: ACM SIGPLAN Notices (1996)

We define a weak lambda;-calculus, lambda; sigma;w, as a subsystem of the full lambda;-calculus with explicit substitutions lambda; sigma; uArr;. We claim that lambda; sigma;w could be the archetypal output language of functional compilers, just as the lambda;-calculus is their universal input language. Furthermore, lambda; sigma; uArr; could be the adequate theory to establish the correctness of simplified functional compilers. Here, we illustrate these claims by proving the correctness of two simplified compilers and runtime systems modeled as abstract machines. We first present the Krivine machine. Then, we give the first formal proofs of Cardelli's FAM and of its compiler.
A New HAD Algorithm for Optimal Routing of Hierarchically Structured Data Networks
Authors: Garng M. Huang, Shan Zhu
Venue: IEEE Transactions on Parallel and Distributed Systems (1996)

In this paper, a new algorithm based on hierarchical aggregation/disaggregation and decomposition/composition (HAD) scheme is proposed to solve the optimal routing problems (ORP) for hierarchically structured networks of multi-layer backbones. Our algorithm has two major differences with the existing HAD algorithms for hierarchically clustered networks [1], [2]: 1) our algorithm works with more general networks than the networks with the clustered structure; 2) our algorithm parallelizes the computations for different commodities (message flows defined by a pair of origin node and destination node) so that it speeds up with a parallel time complexity of O(mlog2(n)), which is much less than O(Mlog2(n)) needed for the existing HAD algorithms. Here, n is the number of nodes in the network; M is the number of commodities and m is a positive number usually much smaller than M and is a function of the patterns of all the commodities including the locations of all origin nodes and destination nodes, and the flow demand of each commodity. Furthermore, our algorithm can make a trade-off between the run time and the optimality, i.e., by allowing the solution to be sub-optimal, our algorithm can save great amount of computation time. The implementation of the algorithm for a 200-node network is simulated using OPNET simulation package (OPNET or Optimized Network Engineering Tools is developed by MIL3, Inc.), and the test results are consistent with our analysis.
Detecting coarse-grain parallelism using an interprocedural parallelizing compiler
Authors: Mary H. Hall, Saman P. Amarasinghe, Brian R. Murphy, Shih-Wei Liao, Monica S. Lam
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

This paper presents an extensive empirical evaluation of an interprocedural parallelizing compiler, developed as part of the Stanford SUIF compiler system. The system incorporates a comprehensive and integrated collection of analyses, including privatization and reduction recognition for both array and scalar variables, and symbolic analysis of array subscripts. The interprocedural analysis framework is designed to provide analysis results nearly as precise as full inlining but without its associated costs. Experimentation with this system shows that it is capable of detecting coarser granularity of parallelism than previously possible. Specifically, it can parallelize loops that span numerous procedures and hundreds of lines of codes, frequently requiring modifications to array data structures such as privatization and reduction transformations. Measurements from several standard benchmark suites demonstrate that an integrated combination of interprocedural analyses can substantially advance the capability of automatic parallelization technology.
Organization of final year projects
Authors: Kenneth M. Dawson-Howe
Venue: ACM SIGCSE Bulletin (1996)

This paper details a method for the organization of final year computer science projects which has been found to be extremely beneficial both from the point of view of the students and the supervisor. These projects count for 20% of the final degree result in this Department, and are a crucial part of the development of the student.The model proposed for the organization of the projects is one in which the students initially work in a group, co-operatively developing a basic platform on which they can then individually develop their projects. This organization allows the supervision to be achieved through regular group meetings, and provides the students with good experience (and all the benefits) of working in a group, while at the same time fulfilling the objective of getting the student to work on a complex task independently. An example of this project organization in practice, in the field of computer vision, is also detailed.
Systematic software reuse (panel): objects and frameworks are not enough
Authors: Martin Griss, Ivar Jacobson, Chris Jette, Bob Kessler, Doug Lea
Venue: Proceedings of the 1995 Symposium on Software reusability (1995)

Ensuring that object technology will achieve its promise of significant software reuse requires that special attention be paid to a combination of people, process and technology issues. Reuse will not happen automatically. The panelists will describe their experience with OO reuse and their views on the issues.
Fortran program specialization
Authors: Paul Kleinrubatscher, Albert Kriegshaber, Robert Zöchling, Robert Glück
Venue: ACM SIGPLAN Notices (1995)

We have developed and implemented a partial evaluator for a subset of Fortran 77. A partial evaluator is a tool for program transformation which takes as input a general program and a part of its input, and produces as output a specialized program. The goal is efficiency: a specialized program often runs an order of magnitude faster than the general program. The partial evaluator is based on the off-line approach and uses a binding-time analysis prior to the specialization phase. The source language includes multi-dimensional arrays, procedures and functions, as well as global storage. The system is presented and experimental results are given.
The economical method for generating random samples from discrete distributions
Authors: I. Deak
Venue: ACM Transactions on Mathematical Software (TOMS) (1986)

The idea of the economical method is applied for generating samples from any discrete distribution. In the resulting procedure, the expected number of uniformly distributed random numbers is less than in the alias method (practically 1). A refinement gives a version where in limit just one uniformly distributed number is required at the expense of some storage space.
Beware, techies bearing gifts
Authors: Elliot Soloway
Venue: Communications of the ACM (1995)

The latest techie panacea for fixing education is to just connect all the students to the Internet; with all that information out there, surely they will learn. In Project Globe, Vice President Gore, the U.S.'s chief techie, proposes to connect thousands of schools worldwide.
Using video to re-present the user
Authors: Francoise Brun-Cottan, Patricia Wall
Venue: Communications of the ACM (1995)

Advocates of user-centered design and participatory design, also referred to as &ldquo;work practice practitioners&rdquo; include computer scientists, systems designers, software engineers, social scientists, industrial and graphic designers, marketing, sales, and service personnel. Working singly or in teams, we have been identifying and combining effective techniques and methods of: gathering data, interacting with user participants, representing activities and observations, and integrating findings with the design and construction of new technologies.
Stochastic Approximation Methods for Systems Over an InfiniteHorizon
Authors: Harold J. Kushner, Felisa J. Vazquez-Abad
Venue: SIAM Journal on Control and Optimization (1996)

The paper develops efficient and general stochastic approximation (SA) methods for improving the operation of parametrized systems of either the continuous- or discrete-event dynamical systems types and which are of interest over a long time period. For example, one might wish to optimize or improve the stationary (or average cost per unit time) performance by adjusting the systems parameters. The number of applications and the associated literature are increasing at a rapid rate. This is partly due to the increasing activity in computing pathwise derivatives and adapting them to the average-cost problem. Although the original motivation and the examples come from an interest in the infinite-horizon problem, the techniques and results are of general applicability in SA. We present an updating and review of powerful ordinary differential equation--type methods, in a fairly general context, and based on weak convergence ideas. The results and proof techniques are applicable to a wide variety of applications. Exploiting the full potential of these ideas can greatly simplify and extend much current work. Their breadth as well as the relative ease of using the basic ideas are illustrated in detail via typical examples drawn from discrete-event dynamical systems, piecewise deterministic dynamical systems, and a stochastic differential equations model. In these particular illustrations, we use either infinitesimal perturbation analysis--type estimators, mean square derivative-type estimators, or finite-difference type estimators. Markov and non-Markov models are discussed. The algorithms for distributed/asynchronous updating as well as the fully synchronous schemes are developed.
The virtual Meiji village
Authors: Hitoshi Nakata
Venue: ACM SIGGRAPH Computer Graphics (1996)

In January of 1995 museum staff and the Kinjo Gakuin University Multimedia Center agreed to design a multimedia project to boost attendance at Museum Meiji Mura. Under the leadership of Hitoshi Nakata, Kinjo Gakuin University professors, Taisei Construction Co. Ltd. computer graphics technicians and Kinjo Media Mix students (a university club for computers and media) worked together to create the Virtual Meiji Village Project. This type of collaboration, though common in the United States, is rarely done in Japan.
APPL/A: a language for software process programming
Authors: Stanley M. Sutton,  Jr., Dennis Heimbigner, Leon J. Osterweil
Venue: ACM Transactions on Software Engineering and Methodology (TOSEM) (1995)

Software process programming is the coding of software processes in executable programming languages. Process programming offers many potential benefits, but their realization has been hampered by a lack of experience in the design and use of process programming languages. APPL/A is a prototype software process programming language developed to help gain this experience. It is intended for the coding of programs to represent and support software processes including process, product, and project management. APPL/A is defined as an extension to Ada, to which it adds persistent programmable relations, concurrent triggers on relation operations (for reactive control), optionally and dynamically enforceable predicates on relations (which may serve as constraints), and composite statements that provide alternative combinations of serializability, atomicity, and consistency enforcement (for programming high-level transactions). APPL/A has been used to code engineering-oriented applications, like requirements specification and design, as well as management-related activities, such as personnel assignment, task scheduling, and project monitoring. APPL/A has also enabled us to experiment with process program design techniques and architectures, including process state reification, intermittent (or persistent) processes, reflexive and metaprocesses, and multiple-process systems. Our ability to address a wide range of software processes and process characteristics indicates that the APPL/A constructs represent important and general capabilities for software process programming. &mdash;Authors' Abstract
On controlling the presentation of information
Authors: Geoffrey Pike
Venue: ACM SIGWEB Newsletter (1995)

One's right to read a newspaper in any conceivable idiosyncratic manner is not questioned. For historical reasons, many people are blind to this right when it comes to other media, such as television, radio, and the World Wide Web. When a signal is transmitted freely, accompanied by begging that people tune in, it seems untenable to charge viewers with copyright violations if they look at the signal, or portions thereof. "Rebroadcasting" is illegal, but anything that happens between legally acquiring information and privately viewing that information is harmless.
A Method of Combining Multiple Experts for the Recognition of Unconstrained Handwritten Numerals
Authors: Y. S. Huang, C. Y. Suen
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1995)

For pattern recognition, when a single classifier cannot provide a decision which is 100 percent correct, multiple classifiers should be able to achieve higher accuracy. This is because group decisions are generally better than any individual¿s. Based on this concept, a method called the ¿Behavior-Knowledge Space Method¿ was developed, which can aggregate the decisions obtained from individual classifiers and derive the best final decisions from the statistical point of view. Experiments on 46,451 samples of unconstrained handwritten numerals have shown that this method achieves very promising performances and outperforms voting, Bayesian, and Dempster-Shafer approaches.
Foundations of multimedia database systems
Authors: Sherry Marcus, V. S. Subrahmanian
Venue: Journal of the ACM (JACM) (1996)

Though numerous multimedia systems exist in the commercial market today, relatively little work has been done on developing the mathematical foundation of multimedia technology. We attempt to take some initial steps towards the development of a theoretical basis for a multimedia information system. To do so, we develop the motion of a structured multimedia database system. We begin by defining a mathematical model of a media-instance. A media-instance may be thought of as &ldquo;glue&rdquo; residing on top of a specific physical media-representation (such as video, audio, documents, etc). Using this &ldquo;glue&rdquo;, it is possible to define a general purpose logical query language to query multimedia data. This glue consists of a set of &ldquo;states&rdquo; (e.g., video frames, audio tracks, etc.) and &ldquo;features&rdquo;, together with relationships between states and/or features. A structured multimedia database system imposes a certain mathematical structures on the set of features/states. Using this notion of a structure, we are able to define indexing structures for processing queries, methods to relax queries when answers do not exist to those queries, as well as sound, complete and terminating procedures to answer such queries (and their relaxations, when appropriate). We show how a media-presentation can be generated by processing a sequence of queries, and furthermore we show that when these queries are extended to include constraints, then these queries can not only generate presentations, but also generate temporal synchronization properties and spatial layout properties for such presentations. We describe the architecture of a prototype multimedia database system based on the principles described in this paper.