ppxscal/embedding_network huggingface dataset:
Contention Resolution with Guaranteed Constant Expected Delay
Authors: Leslie A Goldberg, Philip D. MacKenzie
Venue:  (1997)

We study contention resolution in multiple-access channels such as the Ethernet. Under a stochastic model of continuous packet generation from a set of n processors, we construct a protocol which guarantees constant expected delay for generation rates up to a fixed constant which is less than 1. Previous protocols which are stable for constant arrival rates do not guarantee constant expected delay. The two protocols that achieved results closest to this are one by Raghavan and Upfal, which only guarantees logarithmic (in n) expected delay, and one by Paterson and Srinivasan, which only guarantees constant expected delay with high probability. (In the latter protocol, there is a non-zero probability that the initial clock synchronization might fail and cause the expected delay to grow unboundedly.) Although those protocols do not guarantee constant expected delay, we have used ideas from them in the construction of our protocol, which does guarantee constant expected delay. We achieve our results using a technique called Robust Synchronization which is applied periodically in our protocol. The introduction of this technique and the analysis of this technique are the major contributions of the paper.
Sequences of Revisions: On the Semantics of Nested Conditionals
Authors: Craig Boutilier
Venue:  (1992)

The truth conditions for conditional sentences have been well-studied, but few compelling attempts have been made to define means of evaluating iterated or nested conditionals. We start with a semantic account of subjunctive conditionals based on the AGM model of revision, and extend this model in a natural fashion to account for right-nesting of conditionals, describing a process called ``natural revision''''. These sentences capture sequences of propositional revisions of a knowledge base. We examine the properties of this model, demonstrating that the maximum amount of conditional information in a belief set is preserved after revision. Furthermore, we show how any sequence of revisions can be reduced to natural revision by a single sentence. This demonstrates that any arbitrarily nested sentence is equivalent to a sentence without nesting of the conditional connective. We show cases where revision models, even after the processing of an arbitrary sequence of revisions, can be described purely propositionally, and often in a manner that permits tractable inference. We also examine a form of revision known as ``paranoid revision'''' which appears to be the simplest form of belief revision that fits within the AGM framework, and captures semantically the notion of full meet revision.
A Procedural Model of Recognition for Machine Perception
Authors: William S. Heavens
Venue:  (1978)

This thesis is concerned with aspects of a theory of machine perception. It is shown that a comprehensive theory is emerging from research in computer vision, natural language understanding, cognitive psychology, and Artificial Intelligence programming language technology. A number of aspects of machine perception are characterized. Perception is a recognition process which composes new descriptions of sensory experience in terms of stored steriotypical knowledge of the world. Perception requires both a schema-based formalism for the representation of knowledge and a model of the processes necessary for performing search and deduction on that representation. As an approach towards the development of a theory of machine perception, a computational model of recognition is presented. The similarity of the model to formal mechanisms in parsing theory is discussed. The recognition model integrates top-down, hypothesis-driven search with bottom-up, data-driven search in hierarchical schemata representations. Heuristic procedural methods are associated with particular schemata as models to guide their recognition. Multiple methods may be applied concurrently in both top-down and botton-up search modes. The implementation of the recognition model as an Artificial Intelligence programming language called MAYA is described. MAYA is a multiprocessing dialect of LISP that provides data structures for representing schemata networks and control structures for integrating top-down and bottom-up processing. A characteristic example from scene analysis, written in MAYA, is presented to illustrate the operation of the model and the utility of the programming language. A programming reference manual for MAYA is included. Finally, applications for both the recognition model and MAYA are discussed and some promising directions for future research proposed.
A Logical Framework for Depiction and Image Interpretation
Authors: Raymond Reiter, Alan K. Mackworth
Venue:  (1988)

We propose a logical framework for depiction and interpretation that formalizes image domain knowledge, scene domain knowledge and the depiction mapping between the image and scene domains. This framework requires three sets of axioms: image axioms, scene axioms and depiction axioms. An interpretation of an image is defined to be a logical model of these axioms. \n The approach is illustrated by a case study, a reconstruction in first order logic of a simplified map understanding program, Mapsee. The reconstruction starts with a description of the map and a specification of general knowledge of maps, geographic objects and their depiction relationships. For the simple map world we show how the task level specification may be refined to a provably correct implementation by applying model-preserving transformations to the initial logical representation to produce a set of propositional formulas. The implementation may use known constraint satisfaction techniques to find the set of models of these propositional formulas. In addition, we sketch preliminary logical treatments for image queries, contingent scene knowledge, ambiguity in image description, occlusion, complex objects, preferred interpretations and image synthesis. \n This approach provides a formal framework for analyzing and going beyond existing systems such as Mapsee, and for understanding the use of constraint satisfaction techniques. It can be used as a foundation for the specification, design and implementation of vision and graphics systems that are correct with respect to the task and algorithm levels.
Multiresolution Surface Approximation
Authors: David R. Forsey, David Wong
Venue:  (1995)

This paper presents a method for automatically generating a hierarchical B-spline surface from an initial set of control points. Given an existing mesh of control points a mesh with half the resolution is constructed by simultaneously approximating the finer mesh while minimizing a smoothness constraint using weighted least squares. Curvature measures are used to identify features that need only be represented in the finer mesh. The resulting hierarchical surface accurately and economically reproduces the original mesh, is free from excessive undulations in the intermediate levels and produces a multiresolution representation suitable for animation and interactive modelling.
UNITY Algorithms for Detecting Stable and Non-Stable TerminationConditions in Time Warp Parallel Simulations
Authors: Debra S. Richardson, Marc Abrams
Venue:  (1990)

This paper extends work done by Abrams and Richardson on the topic of implementing global termination conditions and collecting output measures in parallel simulation. Concentrating on the Time Warp method for parallel simulation, an improved categorization scheme for termination conditions is presented, as well as algorithms written in UNITY notation to implement each category.
Graph Embeddings and Simplicial Maps
Authors: Lenwood S. Heath
Venue:  (1993)

An undirected graph is viewed as a simplicial complex. The notion of a graph embedding of a guest graph in a host graph is generalized to the realm of simplicial maps. Dilation is redefined in this more general setting. Lower bounds on dilation for various guest and host graphs are considered. Of particular interest are graphs that have been proposed as communication networks for parallel architectures. Bhatt et al. provide a lower bound on dilation for embedding a planar guest graph in a butterfly host graph. Here, this lower bound is extended in two directions. First, a lower bound that applies to arbitrary guest graphs is derived, using tools from algebraic topology. Second, this lower bound is shown to apply to arbitrary host graphs through a new graph-theoretic measure, called bidecomposability. Bounds on the bidecomposability of the butterfly graph and of the k-dimensional torus are determined. As corollaries to the main lower bound theorem, lower bounds are derived for embedding arbitrary planar graphs, genus g graphs, and k-dimensional meshes in a butterfly host graph. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
Implementing an Intelligent Retrieval System: The CODER System, Version 1.0
Authors: Marybeth T. Weaver, Edward A. Fox
Venue:  (1988)

For individuals requiring interactive access to online text, information storage and retrieval systems provide a way to retrieve desired documents and/or text passages. The CODER (COmposite Document Expert/effective/extended Retrieval) system is a testbed for determining how useful various artificial intelligence techniques are for increasing the effectiveness of information storage and retrieval systems. The system, designed previously, has three components: an analysis subsystem for analyzing and storing document contents, a central spine for manipulations and storage of world and domain knowledge, and a retrieval subsystem for matching user queries to relevant documents. This thesis discusses the implementation of the retrieval subsystem and portions of the spine and analysis subsystem. It illustrates that logic programming, specifically with the Prolog language, is suitable for development of an intelligent information retrieval system. Furthermore, it shows that system modularity provides a flexible research testbed, allowing many individuals to work on different parts of the system which may later be quickly integrated. The retrieval subsystem has been implemented in a modular fashion so that new approaches to information can be easily compared to more traditional ones. A powerful knowledge representation language, a comprehensive lexicon, and individually tailored experts using standardized blackboard modules for communication and control allowed rapid prototyping, incremental development and ready adaptability to change. The system executes on a DEC VAX 11/785 running ULTRIX (TM), a variant of 4.2 BSD UNIX. It has been implemented as a set of MU-Prolog and C modules communicating through TCP/IP sockets.
SCALABLE VISUALIZATION OF PARALLEL SYSTEMS
Authors: Jorge Garcia, Richard Hughey
Venue:  (1994)

As parallel systems become larger and more complex, they become harder to understand. The vast amount of information produced by these systems can quickly overwhelm a person. In many cases, researchers have turned to the use of visualization techniques as an aid to understanding the inner workings of parallel systems. By converting the information to images, a visualization system can take advantage of the human ability to recognize patterns that would not seem obvious otherwise. There are several existing systems for visualizing parallel programs. But most of them present fixed views of data, and will not scale to the thousands of processors available on massively parallel computers. In this paper we present a proposal for research in developing visualizations that scale with the number of processors. The methods used to create these views will make visualization systems useful in understanding computers with any number of processors.
Simulation Support: Prototyping The Automation-Based Paradigm
Authors: Osman Balci, Richard E. Nance
Venue:  (1987)

This paper describes our research efforts in prototyping the automation-based software paradigm to provide automated support for discrete-event simulation model development. The automation-based paradigm has been suggested as the software technology in the 1990''s. The technology needed to support this paradigm does not yet exist. However, the benefits to be gained are so significant that, if achieved, it could profoundly change the way that simulation models are developed. We have been working to achieve this paradigm in the form of an environment composed of an integrated and comprehensive collection of computer-based tools. Our prototyping efforts have focused on the Model Generator, Model Analyzer, and Assistance Manager tools. The Model Generator tool is crucial for the realization of the paradigm and three prototypes have been developed. Our experimentations with the prototypes indicate that the paradigm can be achieved if a small problem domain is chosen. The problem becomes quite complex in the domain-independent case; nevertheless, we believe that the challenge can be met by way of an evolutionary development of prototypes.
Collocation for Singular Perturbation Problems I: First Order Systems with Constant Coefficients
Authors: Uri Ascher, R. Weiss
Venue:  (1981)

The application of collocation methods for the numerical solution of singularly perturbed ordinary differential equations is investigated. Collocation at Gauss, Radau and Lobatto points is considered, for both initial and boundary value problems for first order systems with constant coefficients. Particular attention is paid to symmetric schemes for boundary value problems; these problems may have boundary layers at both interval ends. .br Our analysis shows that certain collocation schemes, in particular those based on Gauss or Lobatto points, do perform very well on such problems, provided that a fine mesh with steps proportional to the layers'' width is used in the layers only, and a coarse mesh, just fine enough to resolve the solution of the reduced problem, is used in between. Ways to construct appropriate layer meshes are proposed. Of all methods considered, the Lobatto schemes appear to be the most promising class of methods, as they essentially retain their usual superconvergence power for the smooth, reduced solution, whereas Gauss-Legendre schemes do not. .br We also investigate the conditioning of the linear systems of equations arizing in the discretization of the boundary value problem. For a row equilibrated version of the discretized system we obtain a pleasantly small bound on the maximum norm condition number, which indicates that these systems can be solved safely by Gaussian elimination with scaled partial pivoting.
A New Approach To Test Sequence Derivation Based on External Behavior Expression (EBE)
Authors: Jianping Wu, Samuel T. Chanson
Venue:  (1989)

This paper presents a new approach to test sequence derivation from formal protocol specifications for protocol conformance testing. The approach is based on a model of External Behaviour Expression (EBE) which specifies only the external behaviour of a protocol in terms of the input/output sequences and their logical (function and predicate) relations, and can be obtained from formal protocol specifications in either Estelle or LOTOS. A basic test derivation theory is defined for the purpose of formalizing test sequence derivation strategies. Based on the EBE of a protocol, a test sequence derivation method is proposed to identify associations between inputs and outputs through the interaction paths and their I/O subpaths. Generic Test Cases generated from these I/O subpaths are based on specific testing purposes. Abstract Test Cases are selected in terms of particular test methods and additional requirements. Comparison to other existing schemes shows the method proposed here is simple and concise, and the resulting set of test sequences is complete and effective. It is our belief that this approach to test sequence derivation can provide the basis of a formalized framework for protocol conformance testing.
Clustering Facial Displays in Context
Authors: Jesse Hoey
Venue:  (2001)

A computer user''s facial displays will be context dependent, especially in the presence of an embodied agent. Furthermore, each interactant will use their face in different ways, for different purposes. These two hypotheses motivate a method for clustering patterns of motion in the human face. Facial motion is described using optical flow over the entire face, projected to the complete orthogonal basis of Zernike polynomials. A context-dependent mixture of hidden Markov models (cmHMM) clusters the resulting temporal sequences of feature vectors into facial display classes. We apply the clustering technique to sequences of continuous video, in which a single face is tracked and spatially segmented. We discuss the classes of patterns uncovered for a number of subjects.
Quantitative Assessment of the Software Maintenance Process
Authors: Joel Henry, Sallie M. Henry, Dennis G. Kafura, Lance Matheson
Venue:  (1993)

This paper describes analysis techniques used to assess quantitatively the software maintenance process of a large military contractor, and the results obtained. The analysis techniques make use of basic data collected throughout the maintenance process. The data collected are extensive and allow the effects of adding a set of functional enhancements to be traced to process activities and product impact. The analysis techniques include data snooping, applied to gain insight into relationships and trends in the data. Simple nonparametric statistical techniques are then applied to test relationships between data items. The results provide valuable information for predicting process and product characteristics, and assessing the maintenance process.
A New Framework for Image Invariants using Basis Expansion
Authors: Yuan Wang
Venue:  (1997)

We propose a general framework for computing invariant features from images. The proposed approach is based on a simple concept of basis expansion. It is widely applicable to many popular basis representations, such as wavelets short-time Fourier analysis, and splines. Exploiting formulations that use both global and local information about shape and color, the new approach is neither strictly global nor local. It has the advantage of tolerating a certain degree of occlusion (unlike global analysis) and does not require estimating high-order derivatives in computing invariants (unlike local analysis), whence is more robust. Furthermore, it enables a quasi-localized, hierarchical shape analysis which is not possible with other known invariant techniques. Unlike most current research on image invariants which concentrates on either geometry or illuminance invariants, the proposed framework is very general and produces invariants which are insensitive to rigid motion, general affine transform, changes of parameterization and scene illumination, and perspective transform. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
CONFIGMAN
Authors: Don Fong
Venue:  (1990)

Configman is a set of programs designed to assist in the software development of distributed applications. The assumed environment is a network of machines running UNIX, with rcp, rsh, and the usual collection of UNIX tools. Configman follows the UNIX philosophy of providing tools rather than solutions. The configman programs provide functions which can be combined with each other, and with other UNIX tools, to meet the needs of a wide range of situations. There are many styles of development possible under UNIX, and configman may not be useful with all of them. As with many other tools, the maximum benefit is obtained when certain conventions are followed. In particular, configman is designed to work well with RCS and make. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
Analysis of Carry Propagation in Addition: An Elementary Approach
Authors: Nicholas Pippenger
Venue:  (2001)

Analysis of Carry Propagation in Addition: An Elementary Approach Nicholas Pippenger Abstract: Our goal in this paper is to analyze carry propagation in addition using only elementary methods (that is, those not involving residues, contour integration, or methods of complex analysis). Our results concern the length of the longest carry chain when two independent uniformly distributed n-bit numbers are added. First, we show using just first- and second-moment arguments that the expected length C_n of the longest carry chain satisfies C_n = log_2 n + O(1). Second, we use a sieve (inclusion-exclusion) argument to give an exact formula for C_n. Third, we give an elementary derivation of an asymptotic formula due to Knuth, C_n = log_2 n + Phi(log_2 n) + O((log n)^4 / n), where Phi(x) is a bounded periodic function of x, with period 1, for which we give both a simple integral expression and a Fourier series. Fourth, we give an analogous asymptotic formula for the variance V_n of the length of the longest carry chain: V_n = Psi(log_2 n) + O((log n)^5 / n), where Psi(x) is another bounded periodic function of x, with period 1. Our approach can be adapted to addition with the "end-around" carry that occurs in the sign-magnitude and 1s-complement representations. Finally, our approach can be adapted to give elementary derivations of some asymptotic formulas arising in connection with radix-exchange sorting and collision-resolution algorithms, which have previously been derived using contour integration and residues.
COMPUTER SCULPTING OF POLYGONAL MODELS USING VIRTUAL TOOLS
Authors: James R. Bill, Suresh K. Lodha
Venue:  (1994)

This report describes a system for interactive manipulation of polygon meshes using virtual sculpting tools and mesh refinement operations. The virtual tools are geometric objects with shapes described by superquadric equations. The user controls a virtual tool to sculpt a free-form polygonal mesh model. The vertices of the mesh respond to the tool in a semi-realistic manner, allowing the user to push, pull, and deform the mesh in a variety of ways. Mesh refinement operations allow the user to control refinement levels and create smooth objects. Interactive shadows and a virtual trackball considerably enhance the intuitive manipulation and sculpting of models. The strength of the system has been demonstrated by sculpting free-form surfaces such as a dog, flower, television set, and dinosaur, all with widely varying levels of detail.