ppxscal/embedding_network huggingface dataset:
Diffusion tree restructuring for indirect reference counting
Authors: Peter Dickman
Venue: Proceedings of the 2nd international symposium on Memory management (2000)

A new variant algorithm for distributed acyclic garbage detection is presented for use in hybrid garbage collectors. The existing fault-tolerance of Piquer's Indirect Reference Counting (IRC) is qualitatively improved by this new approach. The key insight that underpins this work is the observation that the parent of a node in the IRC diffusion tree need not remain constant. The new variant exploits standard mechanisms for implementing diffusion trees and remote references, using four simple low-cost techniques to dynamically restructure the trees to reduce their depth. This variant reduces third-party dependencies, which make standard IRC vulnerable to process failure, while retaining tolerance of message reordering and without incurring substantial overheads. The paper carefully motivates the algorithm, presents the full technical basis for its development, provides a clear explanation of implementation details and includes an initial discussion of performance issues.
Improved results for route planning in stochastic transportation
Authors: Justin Boyan, Michael Mitzenmacher
Venue: Proceedings of the twelfth annual ACM-SIAM symposium on Discrete algorithms (2001)

In the bus network problem, the goal is to generate a plan for getting from point X to point Y within a city using buses in the smallest expected time. Because bus arrival times are not determined by a fixed schedule but instead may be random, the problem requires more than standard shortest path techniques. In recent work, Datar and Ranade provide algorithms in the case where bus arrivals are assumed to be independent and exponentially distributed. We offer solutions to two important generalizations of the problem, answering open questions posed by Datar and Ranade. First, we provide a polynomial time algorithm for a much wider class of arrival distributions, namely those with increasing failure rate. This class includes not only exponential distributions but also uniform, normal, and gamma distributions. Second, in the case where bus arrival times are independent and geometric discrete random variables, we provide an algorithm for transportation networks of buses and trains, where trains run according to a fixed schedule.
Efficient quantum algorithms for some instances of the non-Abelian hidden subgroup problem
Authors: Gábor Ivanyos, Frédéric Magniez, Miklos Santha
Venue: Proceedings of the thirteenth annual ACM symposium on Parallel algorithms and architectures (2001)

In this paper we show that certain special cases of the hidden subgroup problem can be solved in polynomial time by a quantum algorithm. These special cases involve finding hidden normal subgroups of solvable groups and permutation groups, finding hidden subgroups of groups with small commutator subgroup and of groups admitting an elementary Abelian normal 2-subgroup of small index or with cyclic factor group.
Black box methods for least squares problems
Authors: B. D. Saunders
Venue: Proceedings of the 2001 international symposium on Symbolic and algebraic computation (2001)

We present algorithms to construct an efficient black box for the pseudoinverse, At, of a black box matrix A. This in also known as the Moore-Penrose inverse of A. For the system Ax = b over a subfield of the complex numbers: the vector x = Atb is the least squares solution having the least norm. When we say that A is a black box matrix we mean simply that methods are given to compute the matrix-vector products Au and uTA, for vectors u and vectors v of compatible length. No other assumptions are made about the structure or representation of the matrix. The entries may be integers or rational numbers or elements of a finite field. For the integer or rational case the method uses homomorphic images, and is based on an algorithm capable of computing the black box for the pseudoinverse, when it exists, over an arbitrary field. We discuss the asymptotic costs and some variants that are likely to be useful in practice. Over a finite field the solution, x = Atb, is uniquely defined when it exists. The ability to produce this particular solution is a useful addition to the range of ways solution to singular linear systems may be offered in the black box model.
Robust Real-Time Periodic Motion Detection, Analysis, and Applications
Authors: Ross Cutler, Larry S. Davis
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2000)

We describe new techniques to detect and analyze periodic motion as seen from both a static and a moving camera. By tracking objects of interest, we compute an object's self-similarity as it evolves in time. For periodic motion, the self-similarity measure is also periodic and we apply Time-Frequency analysis to detect and characterize the periodic motion. The periodicity is also analyzed robustly using the 2D lattice structures inherent in similarity matrices. A real-time system has been implemented to track and classify objects using periodicity. Examples of object classification (people, running dogs, vehicles), person counting, and nonstationary periodicity are provided.
Ethernet: distributed packet switching for local computer networks
Authors: Robert M. Metcalfe, David R. Boggs
Venue: Communications of the ACM (1976)

Ethernet is a branching broadcast communication system for carrying digital data packets among locally distributed computing stations. The packet transport mechanism provided by Ethernet has been used to build systems which can be viewed as either local computer networks or loosely coupled multiprocessors. An Ethernet's shared communication facility, its Ether, is a passive broadcast medium with no central control. Coordination of access to the Ether for packet broadcasts is distributed among the contending transmitting stations using controlled statistical arbitration. Switching of packets to their destinations on the Ether is distributed among the receiving stations using packet address recognition. Design principles and implementation are described based on experience with an operating Ethernet of 100 nodes along a kilometer of coaxial cable. A model for estimating performance under heavy loads and a packet protocol for error controlled communication are included for completeness.
Performance evaluation of highly concurrent computers by deterministic simulation
Authors: B. Kumar, E. S. Davidson
Venue: Communications of the ACM (1978)

Simulation is presented as a practical technique for performance evaluation of alternative configurations of highly concurrent computers. A technique is described for constructing a detailed deterministic simulation model of a system. In the model a control stream replaces the instruction and data streams of the real system. Simulation of the system model yields the timing and resource usage statistics needed for performance evaluation, without the necessity of emulating the system. As a case study, the implementation of a simulator of a model of the CPU-memory subsystem of the IBM 360/91 is described. The results of evaluating some alternative system designs are discussed. The experiments reveal that, for the case study, the major bottlenecks in the system are the memory unit and the fixed point unit. Further, it appears that many of the sophisticated pipelining and buffering techniques implemented in the architecture of the IBM 360/91 are of little value when high-speed (cache) memory is used, as in the IBM 360/195.
Development of PPRAM-link interface (PLIF) IP core for high-speed inter-SoC communication
Authors: Takanori Okuma, Koji Hashimoto, Kazuaki Murakami
Venue: Proceedings of the 2001 Asia and South Pacific Design Automation Conference (2001)

We are proposing "PPRAM-Link": a new high-speed communication standard for merged-DRAM/logic SoC architecture. PPRAM-Link standard is composed of physical/logical layers and an API for the upper software layer, which are standardized by PPRAM Consortium. We developed a PPRAM-Link Interface IP family, or "PLIF Core" that realizes logical protocols necessary for subaction-level communications, and it can be applied to various applications. In addition, we designed an FPGA-based PCI-to-PPRAM-Link board for inter-PC/WS communications.
Shape matching using edit-distance: an implementation
Authors: Philip N. Klein, Thomas B. Sebastian, Benjamin B. Kimia
Venue: Proceedings of the twelfth annual ACM-SIAM symposium on Discrete algorithms (2001)

We report on our experience with the implementation of an algorithm for comparing shapes by computing the edit-distance between their medial axes. A shape-comparison method that is robust to various visual transformations has several applications in computer vision, including organizing and querying an image database, and object recognition. There are two components to research on this problem, mathematical formulation of the shape-comparison problem and the computational solution method. We have a clear, well-defined formulation and polynomial-time algorithms for solution. Previous research has involved either ill-defined formulations or heuristic methods for solution. Our starting-point for the implementation is the edit-distance algorithm of Klein et al. [6]. We discuss how we altered that algorithm to handle rotation-invariance while keeping down the time and storage requirements. Most important, we define costs for the edit-operations and give an algorithm for computing them. We use a database of shapes to illustrates that our approach performs intuitively in categorization and indexing tasks, and our results are better than previous approaches.
Visual tool for teaching synchronization problems in operating systems
Authors: M. Afzal Bhatti
Venue: ACM SIGCSE Bulletin (2000)

During the last several years, many attempts were made to prove that information technology (IT) holds great promise for education. For that purpose all over world, research has been carried out on the instructional use of IT in education. The results of the research activity have repeatedly proven that computers can be powerful educational tools. Information technology, when properly used, can improve learning, motivate students, and help them gain higher-level cognitive skills critical to lifelong learning. Yet, despite the proven success of instructional computing, it has not yet been fully adopted in meaningful way into computer science education at university level. The paper is about an attempt to use information technology to teach basic concepts in one of the core computer science courses---operating systems---in a modest computing environment.
An open approach for deploying programming nodes into communication networks
Authors: Cris Amon C. Rocha, Aécio Paiva Braga, José Neuman de Souza
Venue: Workshop on Data communication in Latin America and the Caribbean (2001)

Nowadays, we are facing in the computer network reserach communication new challenges related to the concepts of programmable and active networks. Great efforts have been spent to make current data communication networks more flexible and dynamic. Unfortunately, such efforts are followed by complexity and, therefore, the process of deploying the mechanisms has been committed. In order to make this process simpler, this work presents an open approach for having programmable nodes that make computer networks more dynamic in terms of adding new services without increasing complexity. This approach presents SNPI (Simple Network Programmable Interface), which is group of skeletons and data structures resources that make possible to the programmers and developers a fast deployment of new services into the network. The mechanism presented allows that access to internal mechanisms of data flow processing in the network nodes.
A web-based little man computer simulator
Authors: William Yurcik, Larry Brumbaugh
Venue: ACM SIGCSE Bulletin (2001)

This paper describes a web-based simulation tool which can be used to teach introductory computer organization based on the conceptual paradigm of a Little Man Computer. Specifically we share examples how this tool can be used to improve student comprehension of the interaction between computer architecture, assembly language, and the operating system.
Some thoughts on parallel processing
Authors: Lynn D. Yarbrough
Venue: Communications of the ACM (1960)

In the past two years or so I have seen a number of papers and heard a number of talks describing the characteristics of (and the wonders inherent in) certain computers like Gamma 60, LARC, H-800, STRETCH, and others. Of course, all these machines share a capacity for parallel asynchronous multiple processing. Now this is a truly marvelous property, especially from the point of view of the common variety of &ldquo;my-job's-on-the-machine-keep-your-cotton-pickin'-hands-off&rdquo; programmer.
Fully automatic assessment of programming exercises
Authors: Riku Saikkonen, Lauri Malmi, Ari Korhonen
Venue: Proceedings of the 6th annual conference on Innovation and technology in computer science education (2001)

Automatic assessment of programming exercises has become an important method for grading students' exercises and giving feedback for them in mass courses. We describe a system called Scheme-robo, which has been designed for assessing programming exercises written in the functional programming language Scheme. The system assesses individual procedures instead of complete programs. In addition to checking the correctness of students' solutions the system provides many different tools for analysing other things in the program like its structure and running time, and possible plagiarism. The system has been in production use on our introductory programming course with some 300 students for two years with good results.
Synthesis of Resource Invariants for Concurrent Programs
Authors: Edmund Clarke,  Jr.
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1980)

Owicki and Gries have developed a proof system for conditional critical regions. In their system, logically related variables accessed by more than one process are grouped together as resources, and processes are allowed access to a resource only in a critical region for that resource. Proofs of synchronization properties are constructed by devising predicates called resource invariants which describe relationships among the variables of a resource when no process is in a critical region for the resource. In constructing proofs using the system of Owicki and Gries, the programmer is required to supply the resource invariants. Methods are developed in this paper for automatically synthesizing resource invariants. Specifically, the resource invariants of a concurrent program are characterized as least fixpoints of a functional which can be obtained from the text of the program. By the use of this fixpoint characterization and a widening operator based on convex closure, good approximations may be obtained for the resource invariants of many concurrent programs.
CMOS Design of a Current-Mode Multiplier/Divider Circuit with Applications to Fuzzy Controllers
Authors: Iluminada Baturone, Santiago Sánchez-Solano, José L. Huertas
Venue: Analog Integrated Circuits and Signal Processing (2000)

Multiplier and divider circuits are usually required in the fields of analog signal processing and parallel-computing neural or fuzzy systems. In particular, this paper focuses on the hardware implementation of fuzzy controllers, where the divider circuit is usually the bottleneck. Multiplier/divider circuits can be implemented with a combination of A/D-D/A converters. An efficient design based on current-mode data converters is presented herein. Continuous-time algorithmic converters are chosen to reduce the control circuitry and to obtain a modular design based on a cascade of bit cells. Several circuit structures to implement these cells are presented and discussed. The one that is selected enables a better trade-off speed/power than others previously reported in the literature while maintaining a low area occupation. The resulting multiplier/divider circuit offers a low voltage operation, provides the division result in both analog and digital formats, and it is suitable for applications of low or middle resolution (up to 9 bits) like applications to fuzzy controllers. The analysis is illustrated with Hspice simulations and experimental results from a CMOS multiplier/divider prototype with 5-bit resolution. Experimental results from a CMOS current-mode fuzzy controller chip that contains the proposed design are also included.
Robust Segmentation of Primitives from Range Data in the Presence of Geometric Degeneracy
Authors: David Marshall, Gabor Lukacs, Ralph Martin
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2001)

This paper addresses a common problem in the segmentation of range images. We would like to identify and fit surfaces of known type wherever these are a good fit. This paper presents methods for the least-squares fitting of spheres, cylinders, cones, and tori to 3D point data, and their application within a segmentation framework. Least-squares fitting of surfaces other than planes, even of simple geometric type, has been rarely studied. Our main application areas of this research are reverse engineering of solid models from depth-maps and automated 3D inspection where reliable extraction of these surfaces is essential. Our fitting method has the particular advantage of being robust in the presence of geometric degeneracy, i.e., as the principal curvatures of the surfaces being fitted decrease (or become more equal), the results returned naturally become closer and closer to those surfaces of ¿simpler type,¿ i.e., planes, cylinders, cones, or spheres, which best describe the data. Many other methods diverge because, in such cases, various parameters or their combination become infinite.
Identifying topics for instructional improvement through on-line tracking of programming assignments
Authors: Dorota M. Huizinga
Venue: Proceedings of the 6th annual conference on Innovation and technology in computer science education (2001)

This paper stresses the need for identifying specific learning objectives for student programming projects and describes the use of an on-line project submission system for assessment of those objectives. Specifically, the emphasis of the article is on on-line tracking of student progress in order to identify topics that need particular instructional attention. The examples and data collected are drawn from a junior level operating system course.
A Deflated Version of the Conjugate Gradient Algorithm
Authors: Y. Saad, M. Yeung, J. Erhel, F. Guyomarc'h
Venue: SIAM Journal on Scientific Computing (1999)

We present a deflated version of the conjugate gradient algorithm for solving linear systems. The new algorithm can be useful in cases when a small number of eigenvalues of the iteration matrix are very close to the origin. It can also be useful when solving linear systems with multiple right-hand sides, since the eigenvalue information gathered from solving one linear system can be recycled for solving the next systems and then updated.
ELIZA &mdash; a computer program for the study of natural language communication between man and machine
Authors: Joseph Weizenbaum
Venue: Communications of the ACM (1983)

ELIZA is a program operating within the MAC time-sharing system of MIT which makes certain kinds of natural language conversation between man and computer possible. Input sentences are analyzed on the basis of decomposition rules which are triggered by key words appearing in the input text. Responses are generated by reassembly rules associated with selected decomposition rules. The fundamental technical problems with which ELIZA is concerned are: (1) the identification of key words, (2) the discovery of minimal context, (3) the choice of appropriate transformations, (4) generation of responses in the absence of key words, and (5) the provision of an editing capability for ELIZA &ldquo;scripts&rdquo;. A discussion of some psychological issues relevant to the ELIZA approach as well as of future developments concludes the paper.
Is Sometimes Ever Better Than Always?
Authors: David Gries
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1979)

The &ldquo;intermittent assertion&rdquo; method for proving programs correct is explained and compared with the conventional method. Simple conventional proofs of iterative algorithms that compute recursively defined functions, including Ackermann's function, are given.
Implementing a high-integrity executive using Ravenscar
Authors: Neil Audsley, Alan Burns, Andy Wellings
Venue: ACM SIGAda Ada Letters (2001)

This paper discusses the use of the Ravenscar profile in the implementation of an APEX-compliant high-integrity executive. In general, the Ravenscar profile was found to have enough expressive power to implement a large proportion of the executive. However, the lack of dynamic priorities and single item queues were problematic.
Use of a Nonprocedural Specification Language and Associated Program Generator in Software Development
Authors: N. S. Prywes, Amir and S. Shastry
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1979)

The Model II language and the associated program generator are used to explain and illustrate the use of very high level nonprocedural languages for computer programming. The effect of a very high level language is obtained in Model II through the elimination of procedural and control facilities that exist in high level programming languages such as PL/I or Cobol. In particular, the statements may be given in any order and there are no control constructs such as input/output, iterations, and memory allocation. The task of ordering the statements for execution and providing control statements is performed by the automatic program generator. The specification of a program is therefore much shorter (approximately one-fifth) than the equivalent high level procedural language program. Most important, a user need not regard the task of specifying a program as defining a process but rather as describing data and relations. This point of view greatly reduces the computer programming proficiency required of a user. The paper focuses on an example of the use of the language in business data processing, its advantages, and its novelty. It only briefly reviews the methodology incorporated in the existing program generator, a detailed description of which may be found in the references.
On the Fitting of Surfaces to Data with Covariances
Authors: Wojciech Chojnacki, Michael J. Brooks, Anton van den Hengel, Darren Gawley
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2000)

We consider the problem of estimating parameters of a model described by an equation of special form. Specific models arise in the analysis of a wide class of computer vision problems, including conic fitting and estimation of the fundamental matrix. We assume that noisy data are accompanied by (known) covariance matrices characterizing the uncertainty of the measurements. A cost function is first obtained by considering a maximum-likelihood formulation and applying certain necessary approximations that render the problem tractable. A novel, Newton-like iterative scheme is then generated for determining a minimizer of the cost function. Unlike alternative approaches such as Sampson's method or the renormalization technique, the new scheme has as its theoretical limit the minimizer of the cost function. Furthermore, the scheme is simply expressed, efficient, and unsurpassed as a general technique in our testing. An important feature of the method is that it can serve as a basis for conducting theoretical comparison of various estimation approaches.