ppxscal/embedding_network huggingface dataset:
Feature Extraction for Very Low Bit Rate Video Coding
Authors: P. R. Meulemans, R. G. Wilson
Venue:  (1995)

The work described in this report is part of a project aimed at the design of an image sequence (video) coding method for very low bit-rates. The coding method will use multiresolution affine motion estimation combined with extracted image features to make accurate inter-frame predictions. This report is mainly concerned with extracting linear features (i.e lines and edges) from an image and combining them into more complex features that represent object boundaries in the image. The linear features are extracted in a multiresolution scheme from local frequency estimates provided by the Multiresolution Fourier Transform (MFT).
Non-Malleable Cryptography
Authors: D. Dolev, C. Dwork, M. Naor
Venue:  (1995)

The notion of non-malleable cryptography, an extension of semantically secure cryptography, is defined. Informally, the additional requirement is that given the ciphertext it is impossible to generate a different ciphertext so that the respective plaintexts are related. The same concept makes sense in the contexts of string commitment and zero-knowledge proofs of possession of knowledge. Non-malleable schemes for each of these three problems are presented. The schemes do not assume a trusted center; a user need not know anything about the number or identity of other system users.
A Comparison of the LBG and EM Algorithms for Vector Quantization in a Speaker Independent Digit Recognition Task
Authors: Christopher J.S. deSilva, Yaxin Zhang, Yianni Attikiouzel, M. D. Alder
Venue:  (1991)

Abstract unavailable.
Synchronization in Nested Transactions
Authors: Rodolfo F Resende
Venue:  (1994)

Database systems take advantage of concurrent activities in order to offer better throughput and response time for programs accessing the shared data. In spite of employing concurrency, database systems offer a a programming environment where the applications programmer is not required to write programs that have to synchronize to each other. The scheduler is the database system component that manages the concurrent accesses. The execution of application programs as seen by the scheduler is called a transaction. The scheduler ensures that, in spite of the possible interleaving of accesses, the effects of the transactions will appear atomic to each other. The scheduler does this by following a concurrency control protocol. Transaction atomicity in terms of concurrency control issues is know as {\it serializability}. Most of the schedulers ensures conflict serializability, by basing their decisions on a conflict or commutativity based predicate defined on the atomic operations invoked by the transactions. Conflict and commutativity predicates capture the notion of a potential interference between transactions. Traditional serializability theory deals with ``flat'''' transactions, i.e., transactions that can only call atomic database operations. This dissertation presents two contributions in the area of serializability of a special type of transaction called nested transactions. Nested transactions mainly differ from traditional or ``flat'''' transactions in the sense that they offer concurrency control within transactions by serializing subtransactions, i.e., transactions can call other transactions. There exists two components in a nested transaction execution. The first component is the hierarchy of transactions and the second is the level of the atomic database accesses operations. Our first contribution is a theoretical framework where the serializability of nested transactions can be formally proven. Such framework can be used whenever serializability is based on a conflict predicate at the level of the atomic database access operations. The second contribution is the specification of protocols that can be used in schedulers coping with nested transactions. The protocols are novel in the sense that they can use semantic information of the programs associated to the hierarchy of transactions in order to enhance concurrency. We present formal correctness proofs of the proposed protocols.
Modeling Networks with Dynamic Topologies
Authors: Robert L. Moose
Venue:  (1988)

Dynamic hierarchical networks represent an architectural strategy for employing adaptive behavior in applications sensitive to highly variable external demands or uncertain internal conditions. The characteristics of such architectures are described, and the significance of adaptive capability is discussed. The necessity for assessing cost/benefit tradeoffs leads to the use of queueing network models. The general model, a network of M/M/1 queues in a random environment, is introduced and then is simplified so that the links may be treated as isolated M/M/1 queues in a random environment. This treatment yields a formula for approximate mean network delay by combining matrix-geometric results (mean queue length and mean delay) for the individual links. A discrete event simulation model is defined as a basis for cross-validation of the analytic model. Conditions under which the analytic model is considered valid are identified through comparison of the two models.
Superperfect Pairs of Trees in Graphs
Authors: L. A. Novak, A. M. Gibbons
Venue:  (1993)

The notion of a superperfect pair of trees is introduced and characterized in detail. It is closely related to the well known notion of a maximally distant pair of trees as well as to some other recently introduced notions such as perfect pairs of trees and hybrid bases. We show (Propositions 1 and 2) that every maximally distant pair is a superperfect pair of trees and every superperfect pairs of trees is a perfect pair of trees. A central result is contained in Theorem 1 which states that a pair of trees (t1,t2) is a superperfect pair of trees iff both set differences and t1\t2and t2\t1 are hybrid bases. An algorithm for finding a superperfect pair, starting with an arbitrary tree, is also described.
DIRECT VOLUME RENDERING OF CURVILINEAR VOLUMES
Authors: Jane Wilhelms, Judy Challinger, Naim Alper, Shankar Ramamoorthy
Venue:  (1998)

Direct volume rendering makes it possible to visualize sampled 3D scalar data as a continuous medium or to extract features, avoiding the necessity of making binary decisions inherent in methods which extract geometrical representations. However, direct rendering is generally slow and images must be recomputed, to a significant extent, for different viewpoints. Furthermore, most algorithms for direct volume rendering have assumed rectilinear gridded data. This paper discusses methods for using direct volume rendering when the original volume is curvilinear, i.e., is divided into six-sided cells which are not necessarily equilateral hexahedra. One approach is to ray-cast such volumes directly. An alternative approach is to interpolate the sample volumes to a rectilinear grid, and use this regular volume for rendering. Advantages and disadvantages of the two appraoches in terms of speed and image quality are explored.
AN UNEXPECTED FACTOR IN TESTING FOR CMOS OPENS: THE DIE SURFACE
Authors: Haluk Konuk, F. J Ferguson
Venue:  (1996)

In this paper, we for the first time present experimental evidence that the die surface can act as an RC interconnect, becoming an important factor in determining the voltage of a floating wire created by a CMOS open. We present a circuit model for this effect verified with HSPICE simulations. A detailed analysis of potential mechanisms behind this phenomenon is provided. We also present our measurement results for the trapped charge deposited on floating gates during fabrication.
The Multiclass Probabilistic Neural Network (PNN) Classifier
Authors: Anthony Zaknich
Venue:  (1990)

This paper describes a general multiclass classification algorithm called the Probabilistic Neural Network (PNN) (Specht, 1988). Its decision surfaces approach the Bayes- optimal boundaries by non-parametric probability density function (PDF) estimation as the number of training samples grow. Theoretical and practical aspects of the PNN classification method are discussed as well as its advanatages and disadvantages in comparison to the Backpropagation Network (BN). The algorithm has been implemented primarily as a research tool for feature selection and classification for general Pattern Recognition (PR) problems. It will also be used for classifier-directed signal processing tasks. The method has been successfully used to distinguish amongst the resonant sounds of five thin metal gongs of different regular shapes having the same areas and thicknesses. This example application includes a description of data sampling, primary analysis, feature selection and classification which can be usefully generalised to other similar classification problems. Some other PNN applications investigated by the author and others mentioned in the literature are described to show some of the PNN''sfeatures and uses. These include a Bayes-optimal maximum liklehood signal detector, ship hull classification from sonar signals and electrocardiogram classifications from QRX complexes.
Learning and Making Decisions When Costs and Probabilities are Both Unknown
Authors: Bianca Zadrozny, Charles Elkan
Venue:  (2001)

In many machine learning domains, misclassification costs are different for different examples, in the same way that class membership probabilities are example-dependent. In these domains, both costs and probabilities are unknown for test examples, so both cost estimators and probability estimators must be learned. This paper first discusses how to make optimal decisions given cost and probability estimates, and then presents decision tree learning methods for obtaining well-calibrated probability estimates. The paper then explains how to obtain unbiased estimators for example- dependent costs, taking into account the difficulty that in general, probabilities and costs are not independent random variables, and the training examples for which costs are known are not representative of all examples. The latter problem is called sample selection bias in econometrics. Our solution to it is based on Nobel prize-winning work due to the economist James Heckman. We show that the methods we propose are successful in a comprehensive comparison with MetaCost that uses the well-known and difficult dataset from the KDD''98 data mining contest.
Composite Model Checking: Verification with Type-Specific Symbolic Representations
Authors: Tevfik Bultan, Richard Gerber, Christopher League
Venue:  (1999)

In recent years, there has been a surge of progress in automated verification methods based on state exploration. In areas like hardware design, these technologies are rapidly augmenting key phases of testing and validation. To date, one of the most successful of these methods has been symbolic model checking, in which large finite-state machines are encoded into compact data structures such as binary decision diagrams (BDDs) -- and are then checked for safety and liveness properties. However, these techniques have not realized the same success on software systems. One limitation is their inability to deal with infinite-state programs -- even those with a single unbounded integer. A second problem is that of finding efficient representations for various variable types. We recently proposed a model checker for integer-based systems that uses arithmetic constraints as the underlying state representation. While this approach easily verified some subtle, infinite-state concurrency problems, it proved inefficient in its treatment of boolean and (unordered) enumerated types -- which are not efficiently representable using arithmetic constraints. In this paper we present a new technique that combines the strengths of both BDD and arithmetic constraint representations. Our composite model merges multiple type-specific symbolic representations in a single model checker. A system''s transitions and fixpoint computations are encoded using both BDD (for boolean and enumerated types), and arithmetic constraint (for integers) representations, where the choice depends on the variable types. Our composite model checking strategy can be extended to other symbolic representations provided that they support operations such as intersection, union, complement, equivalence checking and relational image computations. We also present conservative approximation techniques for composite representations to address the undecidability of model checking on infinite-state systems. We demonstrate the effectiveness of our approach by analyzing two example systems which include a mixture of booleans, integers and enumerated types. One of them is a requirements specification for the control software of a nuclear reactor''s cooling system, and the other one is a transport protocol specification.
Syntax Error Handling in Language Translation Systems
Authors: J. A. Dain
Venue:  (1991)

Compilers, interpreters, editors are examples of language translation systems which are an essential component of computing. Such systems need to be able to handle most kinds of input, including input that is syntactically incorrect, according to the context-free grammar rules for the system. The paper surveys syntax error handling in theory and in practice. Two theoretical models for syntax errors are minimum distance errors, based on the number of operations needed to transform an incorrect string into a correct one, and parser defined errors, based on correct prefixes. Constraintson languages that can be handled are given and different parsing methods are compared. Error reporting is important because it is the user interface for error handling. Good error messages are precise, informative and constructive. Concepts and techniques for error recovery schemes are explained. Goals for good error recovery are set and practical, implemented schemes are evaluated and their performance compared. A minimum standard of acceptable performance on three-quarters of a data set of Pascal programs is set. Future directions for research are indicated, with particular refernce to the problems posed by error handling for interactive programming environments. 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
EXPONENTIATED GRADIENT VERSUS GRADIENT DESCENT FOR LINEAR PREDICTORS
Authors: Jyrki Kivinen, Manfred Warmuth
Venue:  (1994)

We consider two algorithm for on-line prediction based on a linear model. The algorithms are the well-known Gradient Descent (GD) algorithm and a new algorithm, which we call EG(+/-). They both maintain a weight vector using simple updates. For the GD algorithm, the update is based on subtracting the gradient of the squared error made on a prediction. The EG(+/-) algorithm uses the components of the gradient in the exponents of factors that are used in updating the weight vector multiplicatively. We present worst-case loss bounds for EG(+/-) and compare them to previously known bounds for the GD algorithm. The bounds suggest that the losses of the algorithms are in general incomparable, but EG(+/-) has a much smaller loss if only a few components of the input are relevant for the predictions. We have performed experiments, which show that our worst-case upper bounds are quite tight already on simple artificial data.
Finding All Isolated Solutions To Polynomial Systems Using Hompack
Authors: Alexander P. Morgan, Andrew J. Sommese, Layne T. Watson
Venue:  (1987)

Although the theory of polynomial continuation has been established for over a decade (following the work of Garcia, Zangwill, and Drexler), it is difficult to solve polynomial systems using continuation in practice. Divergent paths (solutions at infinity), singular solutions, and extreme scaling of coefficients can create catastrophic numerical problems. Further, the large number of paths that typically arise can be discouraging. In this paper we summarize polynomial-solving homotopy continuation and report on the performance of three standard path-tracking algorithms (as implemented in HOMPACK) in solving three physical problems of varying degrees of difficulty. Our purpose is to provide useful information on solving polynomial systems; including specific guidelines for homotopy construction and parameter settings. The m-homogeneous strategy for constructing polynomial homotopies is outlined, along with more tradition approaches. Computational comparisons are included to illustrate and contrast the major HOMPACK options. The conclusions summarize our numerical experience and discuss areas for future research.
On the Complexity of Buffer Allocation in Message Passing Systems
Authors: Alex Brodsky, Jan B. Pedersen, Alan Wagner
Venue:  (2003)

Message passing programs commonly use buffers to avoid unnecessary synchronizations and to improve performance by overlapping communication with computation. Unfortunately, using buffers makes the program no longer portable, potentially unable to complete on systems without a sufficient number of buffers. Effective buffer use entails that the minimum number needed for a safe execution be allocated. We explore a variety of problems related to buffer allocation for safe and efficient execution of message passing programs. We show that determining the minimum number of buffers or verifying a buffer assignment are intractable problems. However, we give a polynomial time algorithm to determine the minimum number of buffers needed to allow for asynchronous execution. We extend these results to several different buffering schemes, which in some cases make the problems tractable.
Assigning Labels in Unknown Anonymous Networks
Authors: P. Fraigniaud, A. Pelc, D. Peleg, S. Perennes
Venue:  (2000)

We consider the task of distributedly assigning distinct labels to nodes of an unknown anonymous network. A priori, nodes do not have any identities (anonymous network) and do not know the topology or the size of the network (unknown network). They execute identical algorithms, apart from a distinguished node, called the source, which starts the labeling process. Our goal is to assign short labels, as fast as possible. The quality of a labeling algorithm is measured by the range from which the algorithm picks the labels, or alternatively the length of the assigned labels. Natural efficiency measures are the time, i.e., the number of rounds required for the label assignment, and the message and bit complexities of the label assignment protocol, i.e., the total number of messages (resp., bits) circulating in the network. We present label assignment algorithms whose time and message complexity are asymptotically optimal and which assign short labels. On the other hand, we establish inherent trade-offs between quality and efficiency for labeling algorithms.
Crumbling Walls: A Class of High Availability Quorum Systems
Authors: D. Peleg, A. Wool
Venue:  (1994)

A quorum system is a collection of sets (quorums) every two of which have a nonempty intersection. Quorum systems have been used for a number of applications in the area of distributed systems. The most available quorum systems are the non-dominated coteries (NDC). In this paper we introduce a general class of quorum systems called Crumblng Walls and study its properties.
Cost-Effective Parallel Processing for H-squared/H-to infinity Controller Synthesis
Authors: Ge Yuzhen, Layne T. Watson, Emmanuel G. Collins
Venue:  (1995)

A distributed version of a homotopy algorithm for solving the H-squared/H-to infinity mixed-norm controller synthesis problem is presented. The main purpose of the study is to explore the possibility of achieving high performance with low cost. Existing UNIX workstations running PVM (Parallel Virtual Machine) are utilized. Only the Jacobian matrix computation is distributed and therefore the modification to the original sequential code is minimal. The same algorithm has also been implemented on an Intel Paragon parallel machine. Our implementation shows that acceptable speedup is achieved and the larger the problem sizes, the higher the speedup. Comparing with the results from the Intel Paragon, the study concludes that utilizing the existing UNIX workstations can be a very cost-effective approach to shorten computation time. Furthermore, this economical way to achieve high performance computation can easily be realized and incorporated in a practical industrial design environment.
Formally Reasoning About and Automatically Generating Sequential and Parallel Simulations
Authors: Marc Abrams, Ernest H. Page
Venue:  (1992)

This paper proposes a methodology to automate the construction of simulation programs within the context of a simulation support environment. The methodology starts with a simulation model specification in the form of a set of coupled state transition systems. The paper provides a mechanical method of mapping the transition systems first into a set of formal assertions, permitting formal verification of the transition systems, and second into an executable program. UNITY, a computational model and proof system suitable for development of parallel and distributed programs through step-wise refinement of specifications, is used as the specification and program notation. The methodology provides a means to independently verify the correctness of the transition systems: one can specify properties formally that the model should obey and prove them as theorems using the formal specification.
Multi-Objective Control-Structures Optimization Via Homotopy Methods
Authors: Joanna Rakowska, Robert T. Haftka, Layne T. Watson
Venue:  (1990)

A recently developed active set algorithm for tracking parametrized optima is adapted to multi-objective optimization. The algorithm traces a path of Kuhn-Tucker points using homotopy curve tracking techniques, and is based on identifying and maintaining the set of active constraints. Second order necessary optimality conditions are used to determine nonoptimal stationary points on the path. In the bi-objective optimization case the algoritm is used to trace the curve efficient solutions (Pareto optima). As an example, the algorithm is applied to the simultaneous minimization of the weight and control force of a ten-bar truss with two collocated sensors and actuators, with some interesting results.
Active Disks
Authors: Anurag Acharya, Mustafa Uysal, Joel Saltz
Venue:  (1998)

Several application and technology trends indicate that it might be both profitable and feasible to move computation closer to the data that it processes. In this paper, we evaluate Active Disk architectures which integrate significant processing power and memory into a disk drive and allow application-specific code to be downloaded and executed on the data that is being read from (written to) disk. The key idea is to offload bulk of the processing to the disk-resident processors and to use the host processor primarily for coordination, scheduling and combination of results from individual disks. To program Active Disks, we propose a stream-based programming model which allows disklets to be executed efficiently and safely. Simulation results for a suite of seven algorithms from three application domains (commercial data warehouses, image processing and satellite data processing) indicate that for these algorithms, Active Disks outperform conventional-disk architectures.
A Scheme for Selective Squash and Re-issue for Single-Sided Branch Hammocks
Authors: Karthik Sankaranarayanan, Kevin Skadron
Venue:  (2001)

This abstract describes work to minimize re-execution of control independent instructions. This technique differs from prior work in its emphasis on compiler scheduling in order to minimize changes to the hardware of an out-of-order processor. Work so far has focused on single-sided branch hammocks.