ppxscal/embedding_network huggingface dataset:
Directional Analysis of Images in Scale Space
Authors: Zhi-Qiang Liu, Rangaraj M. Rangayyan, Cyril B. Frank
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1991)

The authors propose a computational technique for the directional analysis of piecewise linear patterns in images based on the notion of zero crossings in gradient images. A given image is preprocessed by a sequence of filters that are second derivatives of 2-D Gaussian functions with different scales. This gives a set of zero-crossing maps (the scale space) from which a stability map is generated. Significant linear patterns are detected from measurements on the stability map. Information regarding orientation of the linear patterns in the image and the area covered by the patterns in specific directions is then computed. The performance of the method is illustrated through applications to a simple test image made up of straight bar patterns as well as to scanning electron microscope images of collagen fibrils in rabbit ligaments. The method has significant applications in quantitative analysis of ligament healing and in comparison of treatment methods for ligament injuries.
Space and Time Bounds on Indexing 3D Models from 2D Images
Authors: David T. Clemens, David W. Jacobs
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1991)

Model-based visual recognition systems often match groups of image features to groups of model features to form initial hypotheses, which are then verified. In order to accelerate recognition considerably, the model groups can be arranged in an index space (hashed) offline such that feasible matches are found by indexing into this space. For the case of 2D images and 3D models consisting of point features, bounds on the space required for indexing and on the speedup that such indexing can achieve are demonstrated. It is proved that, even in the absence of image error, each model must be represented by a 2D surface in the index space. This places an unexpected lower bound on the space required to implement indexing and proves that no quantity is invariant for all projections of a model into the image. Theoretical bounds on the speedup achieved by indexing in the presence of image error are also determined, and an implementation of indexing for measuring this speedup empirically is presented. It is found that indexing can produce only a minimal speedup on its own. However, when accompanied by a grouping operation, indexing can provide significant speedups that grow exponentially with the number of features in the groups.
An architecture for distributed knowledge based-systems
Authors: David A. Carlson, Sudha Ram
Venue: ACM SIGMIS Database (1991)

Many management information systems have requirements that are inherently distributed, both logically and physically, however, no adequate architectures exist which allow multiple knowledge bases and databases to be shared and integrated. An architecture for Distributed Knowledge-Based Systems (DKBS) is presented which satisfies these requirements. A Distributed Knowledge Base Management System (DKBMS) is described which manages the meta-knowledge necessary to coordinate multiple local Knowledge-Based Systems (KBSs). We propose an object-oriented design for implementing the DKBMS structure and the communication protocol which connects the DKBMS with each of the KBSs. An application is described where the DKBS architecture might assist managers to integrate several KBSs which represent parts of a strategic plan.
From student model to teacher model: enriching our view of the impact of computers on society
Authors: Z. Chen
Venue: ACM SIGCAS Computers and Society (1991)

The impact of the computers on society has been studied through student models and the user's mental models, but very little has been said about the methods and practices of the teaching process itself. In this paper the need for teacher models is discussed; a framework for teacher model development is outlined.
Lower bounds for polynomial evaluation and interpolation problems
Authors: Victor Shoup, Roman Smolensky
Venue: Proceedings of the 32nd annual symposium on Foundations of computer science (1991)

It is shown that there is a set of points p/sub 1/, p/sub 2/,. . .,p/sub n/ such that any algebraic program of depth d for polynomial evaluation (or interpolation) at these points has size Omega (n log n/log d). Moreover, if d is a constant, then a lower bound of Omega (n/sup 1+1/d/) is obtained.
Statistical behavior of fast hashing of variable length test strings
Authors: Jacques Savoy
Venue: ACM SIGIR Forum (1990)

In information retrieval, we often have to store and search for a particular record into a large amount of information. For example, during a document indexing process or when a program is trying to spell a text, a dictionary has to be used in an efficient way. A solution to that problem resides in using a hash table. However, if we known many algorithms for manipulating or accessing hash tables [Knuth 73], [Standish 80], [Wiederhold 87], the main problem is to define a "good" hash function for a variable-length string. In order to answer that question our main goals are to present some concrete algorithms and to study their statistical behavior.
Improved Algorithms for Mapping Pipelined and Parallel Computations
Authors: David M. Nicol, David R. O'Hallaron
Venue: IEEE Transactions on Computers (1991)

Recent work on the problem of mapping pipelined or parallel computations onto linear array, shared memory, and host-satellite systems is extended. It is shown how these problems can be solved even more efficiently when computation module execution times are bounded from below, intermodule communication times are bounded from above, and the processors satisfy certain homogeneity constraints. The improved algorithms have significantly lower time and space complexities than the more general algorithms: in one case, an O(nm/sup 3/) time algorithm for mapping m modules onto n processors is replaced with an O(nm log m) time algorithm, and the space requirements are reduced from O(nm/sup 2/) to O(m). Run-time complexity is reduced further with parallel mapping algorithms based on these improvements, which run on the architectures for which they create mappings.
Decomposition of arithmetic expressions to improve the behavior of interval iteration for nonlinear systems
Authors: R. Baker Kearfott
Venue: Computing (1991)

Interval iteration can be used, in conjunction with other techniques, for rigorously bounding all solutions to a nonlinear system of equations within a given region, or for verifying approximate solutions. However, because of overestimation which occurs when the interval Jacobian matrix is accumulated and applied, straightforward linearization of the original nonlinear system sometimes leads to nonconvergent iteration. In this paper, we examine interval iterations based on an expanded system obtained from the intermediate quantities in the original system. In this system, there is no overestimation in entries of the interval Jacobi matrix, and nonlinearities can be taken into account to obtain sharp bounds. We present an example in detail, algorithms, and detailed experimental results obtained from applying our algorithms to the example. &mdash;Author's Abstract
Parallel simulation of stochastic petri nets using recurrence equations
Authors: François Baccelli, Miguel Canales
Venue: Proceedings of the 1992 ACM SIGMETRICS joint international conference on Measurement and modeling of computer systems (1992)

Petri nets provide a powerful modeling formalism, which allows one to describe and study various classes of systems, such as synchronous and asynchronous processes, and/or parallel or sequential ones. We present below a software package, currently under development, that allows the user to specify a stochastic marked graph [1] using either a graphical interface or a specification language. From this specification a simulation program for a Single Instruction Multiple Data (SIMD) parallel machine is generated. A Connection Machine 2 (CM2) is used as the architecture for running this program.
Key issues in HCI curriculum design
Authors: J. Preece, Laurie Keller
Venue: ACM SIGCHI Bulletin (1990)

This paper reports on key issues that needed to be resolved in developing a large postgraduate distance education course in human-computer interaction intended for practicing software developers and technical managers.The multi-disciplinary nature of HCI is identified as being highly controversial when deciding what to teach and how. Questions about the balance of theory verses practice and providing tools verses knowledge are also considered major issues. A less general set of issues including questions such as what is design are also considered. Here, many of the sources of controversy can be traced to higher level issues, in particular the multi-disciplinary nature of HCI.
The four-peg Tower of Hanoi puzzle
Authors: I-Ping Chu, Richard Johnsonbaugh
Venue: ACM SIGCSE Bulletin (1991)

We discuss a version of the Tower of Hanoi puzzle in which there are four pegs rather than three. The fourpeg puzzle provides a rich source of exercises (samples of which are included) for students after the familiar three-peg version has been presented. We give an algorithm that solves the four-peg puzzle in the claimed minimum number of moves (see [2, 4]). Our algorithm solves the four-peg puzzle in O-(4 radic;n) moves whereas the best algorithm for the three-peg puzzle requires 2n - 1 moves. As far as we know, the minimum number of moves required to solve the four-peg puzzle is an open question.
The WINTERP Widget INTERPreter&mdash;a Lisp prototyping and extension environment for OSF/motif based applications user-interfaces
Authors: Niels P. Mayer
Venue: ACM SIGPLAN Lisp Pointers (1990)

Winterp is an interactive, language-based user-interface and application-construction environment enabling rapid prototyping of applications with graphical user interfaces based on the OSF/Motif UI Toolkit. Winterp also serves as a customization environment for delivered applications by providing a real programming language as an extension language. Many existing user-interface languages only have the expressive power to describe static layout of user interface forms; by using a high-level language for extensions and prototyping, Winterp also handles the dynamic aspects of UI presentation, e.g. the use of direct manipulation, browsers, and dialog. Winterp makes rapid prototyping possible because its language is based on an interpreter, thereby enabling interactive construction of application functionality and giving immediate feedback on incremental changes.Winterp's language is based on David Betz's public domain Xlisp interpreter which features a subset of Common Lisp's functionality. The language is extensible, permitting new Lisp primitives to be added in the C language and allowing hybrid implementations constructed from interpreted Lisp and compiled C. Hybrid implementation gives Winterp-based applications the successful extension and rapid-prototyping capabilities of Lisp-based environments, while delivering the multiprocessing perfor- mance of C applications running on personal Unix workstations.
Improved Estimates for the Accuracy of Small Disjuncts
Authors: J. R. Quinlan
Venue: Machine Learning (1991)

Learning systems often describe a target class as a disjunction of conjunctions of conditions. Recent work has noted that small disjuncts, i.e., those supported by few training examples, typically have poor predictive accuracy. One model of this accuracy is provided by the Bayes-Laplace formula based on the number of training examples covered by the disjunct and the number of them belonging to the target class. However, experiments show that small disjuncts associated with target classes of different relative frequencies tend to have different error rates. This note defines the context of a disjunct as the set of training examples that fail to satisfy at most one of its conditions. An empirical adaptation of the Bayes-Laplace formula is presented that also makes use of the relative frequency of the target class in this context. Trials are reported comparing the performance of the original formula and the adaptation in six learning tasks.
Parallel database systems: the future of database processing or a passing fad?
Authors: David J. DeWitt, Jim Gray
Venue: ACM SIGMOD Record (1990)

The concept of parallel database machines consisting of exotic hardware has been replaced by a fairly conventional shared-nothing hardware base along with a highly parallel dataflow software architecture. Such a design provides speedup and scaleup in processing relational database queries. This paper reviews the techniques used by such systems, and surveys current commercial and research systems.
The design and implementation of HoME
Authors: Kazuhiro Ogata, Satoshi Kurihara, Mikio Inari, Norihisa Doi
Venue: ACM SIGPLAN Notices (1992)

HoME is a version of Smalltalk which can be efficiently executed on a multiprocessor and can be executed in parallel by combining a Smalltalk process with a Mach thread and executing the process on the thread. HoME is nearly the same as ordinary Smalltalk except that multiple processes may execute in parallel. Thus, almost all applications running on ordinary Smalltalk can be executed on HoME without changes in their code. HoME was designed and implemented based on the following fundamental policies: (1) theoretically, an infinite number of processes can become active; (2) the moment a process is scheduled, it becomes active; (3) no process switching occurs; (4) HoME is equivalent to ordinary Smalltalk except for the previous three policies. The performance of the current implementation of HoME running on OMRON LUNA-88K, which had four processors, was measured by benchmarks which execute in parallel with multiple processes. In all benchmarks, the results showed that HoME's performance is much better than HPS on the same workstation.
PCF parallel Fortran extensions
Authors: CORPORATE The Parallel Computing Forum
Venue: ACM SIGPLAN Fortran Forum (1991)

This proposed standard was constructed as an effort to provide a uniform spelling of well understood parallel constructs. There was a conscious effort to resist the lure of new constructs unless the evolutionary path from existing practice was clear.
Interactive shadows
Authors: Kenneth P. Herndon, Robert C. Zeleznik, Daniel C. Robbins, D. Brookshire Conner, Scott S. Snibbe, Andries van Dam
Venue: Proceedings of the 5th annual ACM symposium on User interface software and technology (1992)

It is often difficult in computer graphics applications to understand spatial relationships between objects in a 3D scene or effect changes to those objects without specialized visualization and manipulation techniques. We present a set of three-dimensional tools (widgets) called &ldquo;shadows&rdquo; that not only provide valuable perceptual cues about the spatial relationships between objects, but also provide a direct manipulation interface to constrained transformation techniques. These shadow widgets provide two advances over previous techniques. First, they provide high correlation between their own geometric feedback and their effects on the objects they control. Second, unlike some other 3D widgets, they do not obscure the objects they control.
Analytical modelling of a hierarchical buffer for a data sharing environment
Authors: Asit Dan, Daniel M. Dias, Philip S. Yu
Venue: ACM SIGMETRICS Performance Evaluation Review (1991)

In a data sharing environment, where a number of loosely coupled computing nodes share a common storage subsystem, the effectiveness of a private buffer at each node is limited due to the multi-system invalidation effect, particularly under a non-uniform data access pattern. A global shared buffer can be introduced to alleviate this problem either as a disk cache or shared memory. In this paper we developed an approximate analytic model to evaluate different shared buffer management policies (SBMPs) which differ in their choice of data granules to be put into the shared buffer. The analytic model can be used to study the trade-offs of different SBMPs and the impact of different buffer allocations between shared and private buffers. The effects of various parameters, such as, the probability of update, the number of nodes, the sizes of private and shared buffer, etc., on the performance of SBMPS are captured in the analytic model. A detailed simulation model is also developed to validate the analytic model. We show that dependency between the contents of the private and shared buffers can play an important role in determining the effectiveness of the shared buffer particularly for a small number of nodes.
Optimal memory management for time warp parallel simulation
Authors: Yi-Bing Lin, Bruno R. Preiss
Venue: ACM Transactions on Modeling and Computer Simulation (TOMACS) (1991)

Recently there has been a great deal of interest in performance evalution of parallel simulation. Most work is devoted to the time complexity and assumes that the amount of memory available for parallel simulation is unlimited. This paper studies the space complexity of parallel simulation. Our goal is to design an efficient memory management protocol which guarantees that the memory consumption of parallel simulation is of the same order as sequential simulation. (Such an algorithm is referred to as a optimal.) First, we derive the relationships among the space complexities of sequential simulation, Chandy-Misra simulation [2], and Time Warp simulation [7]. We show that Chandy-Misra may consume more storage than sequential simulation, or vice versa. Then we show that Time Warp never consumes less memory than sequential simulation. Then we describe cancelback, an optimal Time Warp memory management protocol proposed by Jefferson. Although cancelback is considered to be complete solution for the storage management problem in Time Warp, some efficiency issues in implementing this algorithm must be considered. We propose an optimal algorithm called artifical rollback. We show that this algorithm is easy to implement and analyze. An implementation of artificial rollback is given, which is integrated with processor scheduling to adjust the memory consumption rate based on the amount of free storage available in the system.
Simplicity Versus Accuracy in a Model of Cache Coherency Overhead
Authors: Susan J. Eggers
Venue: IEEE Transactions on Computers (1991)

The important factors building a model of coherency overhead for a single-bus, shared memory multiprocessor are analyzed. Three architectural features are examined: the size of the coherency block, the cache size, and the type of bus operation used to carry out a particular coherency function. The experiments judge the effect of each architectural parameter on model accuracy by selectively including it in a base model and then comparing the model's predictions of coherency overhead to the results of detailed multiprocessor simulations. The results indicate that coherency block size is critical to include in a model of coherency overhead. This improves the accuracy of the base model by a factor of approximately 5-50, depending on the application. Cache size and the type of coherency-related bus operation are less important, contributing a 1.5% (for 128 kbyte caches) and 6% improvement, respectively, averaged over all traces.
Experiences in integrating distributed shared memory with virtual memory management
Authors: R. Ananthanarayanan, Sathis Menon, Ajay Mohindra, Umakishore Ramachandran
Venue: ACM SIGOPS Operating Systems Review (1992)

While the duality between message-passing and shared memory for interprocess communication is well-known, the shared memory paradigm has drawn considerable attention in recent times even in distributed systems. Distributed Shared Memory (DSM) is the abstraction for supporting the notion of shared memory in a physically non-shared (distributed) architecture. It gives a uniform set of mechanisms for accessing local and remote memories. Further, by combining shared memory style synchronization with the actual data transport in the DSM design, it is possible to provide flexible sharing while assuring mutual exclusion when necessary. This research reports on our experience in implementing a DSM system in an object-based distributed operating system. The important observation from this experience is the need for a tight cooperation between the virtual memory management at each node and the mechanisms provided by the DSM. Such a cooperation is essential to assure good performance of the DSM mechanisms and make the shared memory paradigm viable in a distributed environment.
Symbolic and Neural Learning Algorithms: An Experimental Comparison
Authors: Jude W. Shavlik, Raymond J. Mooney, Geoffrey G. Towell
Venue: Machine Learning (1991)

Despite the fact that many symbolic and neural network (connectionist) learning algorithms address the same problem of learning from classified examples, very little is known regarding their comparative strengths and weaknesses. Experiments comparing the ID3 symbolic learning algorithm with the perception and backpropagation neural learning algorithms have been performed using five large, real-world data sets. Overall, backpropagation performs slightly better than the other two algorithms in terms of classification accuracy on new examples, but takes much longer to train. Experimental results suggest that backpropagation can work significantly better on data sets containing numerical data. Also analyzed empirically are the effects of (1) the amount of training data, (2) imperfect training examples, and (3) the encoding of the desired outputs. Backpropagation occasionally outperforms the other two systems when given relatively small amounts of training data. It is slightly more accurate than ID3 when examples are noisy or incompletely specified. Finally, backpropagation more effectively utilizes a &ldquo;distributed&rdquo; output encoding.
Comments on 'Parallel Algorithms for Hierarchical Clustering and Cluster Validity'
Authors: Fionn Murtagh
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1992)

In the above-titled paper, parallel implementations of hierarchical clustering algorithms that achieve O(n/sup 2/) computational time complexity and thereby improve on the baseline of sequential implementations are described. The latter are stated to be O(n/sup 3/), with the exception of the single-link method. The commenter points out that state-of-the-art hierarchical clustering algorithms have O(n/sup 2/) time complexity and should be referred to in preference to the O(n/sup 3/) algorithms, which were described in many texts in the 1970s. Some further references in the parallelizing of hierarchic clustering algorithms are provided.
A Simulation-Based Estimator for Hidden Markov Random Fields
Authors: Ari Veijanen
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1991)

An estimator for estimating the parameters of a Markov random field X from inaccurate observations is introduced. The author considers first a Markov (Gibbs) random field X=(X/sub i,j/) on a lattice L=((i,j): i=1,2,. . .,n; j=1,2,. . .,m). The marginal distributions of (X/sub i,j/,X/sub i+u,j+v/) (u,v=-1,0,1) are first estimated from an image. Then, random fields X* are simulated with the probability of X*/sub i+u,j+v/)=b nearly equal to the estimate of P(X/sub i,j/=X/sub i+u/,=b). A simulation method similar to the Gibbs sampler is used. The parameters of the Markov random field model are estimated from the X*'s with the pseudolikelihood method.