ppxscal/embedding_network huggingface dataset:
Knowledge acquisition: issues, techniques and methodology
Authors: Yihwa I. Liou
Venue: ACM SIGMIS Database (1992)

The application of expert systems has increased drastically in the last decade. The power of these systems derives from the knowledge they possess, rather than from the inference mechanism that they employ. To ensure the performance of an expert system, the acquisition of knowledge becomes a vital task in the development process. This article discusses issues related to people involved in the knowledge acquisition task, reviews techniques to acquire knowledge, and presents a methodology that offers a structured approach to knowledge acquisition. Trends in knowledge acquisition are discussed.
Some symbolic computing links to the NAG numeric library
Authors: K. A. Broughan, G. Keady, T. D. Robb, M. G. Richardson, M. C. Dewar
Venue: ACM SIGSAM Bulletin (1991)

This article is a semi-popular account intended to help readers compare the three products, SENAC, InterCall and IRENA. Each of the three is in the genre specified in the title of this paper. This article is not a review, as the authors are too closely associated with individual products. For technical detail, see the references below, which, however, treat individual products and generally provide no comparisons.
The multicast policy and its relationship to replicated data placement
Authors: Ouri Wolfson, Amir Milo
Venue: ACM Transactions on Database Systems (TODS) (1991)

In this paper we consider the communication complexity of maintaining the replicas of a logical data-item, in a database distributed over a computer network. We propose a new method, called the minimum spanning tree write, by which a processor in the network should multicast a write of a logical data-item, to all the processors that store replicas of the items. Then we show that the minimum spanning tree write is optimal from the communication cost point of view. We also demonstate that the method by which a write is multicast to all the replicas of a data-item affects the optimal replication scheme of the item, i.e., at which processors in the network the replicas should be located. Therefore, next we consider the problem of determining an optimal replicaiton scheme for a data item, assuming that each processor employs the minimum spanning tree write at run-time. The problem for general networks is shown NP-Complete, but we provide efficient algorithms to obtain an optimal allocation scheme for three common types of network topologies. They are completely-connected, tree, and ring networks. For these topologies, efficient algorithms are also provided for the case in which reliability considerations dictate a minimum number of replicas.
Intensity of end user computing
Authors: Phillip Ein-Dor, Eli Segev
Venue: ACM SIGMIS Database (1991)

Much has been written in recent years on end user computing, based on assumptions concerning the motivations and attributes of end users. Most of this research has been descriptive in nature with little theoretical basis. The empirical study described in this paper was intended to assess factors affecting the intensity of participation in end user computing, while at the same time grounding the research on a firm theoretical base.Theory suggested three major groups of variables affecting intensity of participation in end user computing - organizational factors, top management leadership, and individual factors. Examination of survey data indicated that organizational and top management factors played no part in determining the intensity of EUC while there is a strong relationship between individual factors and intensity of EUC. The individual factors found relevant were reasons for using EUC, use made of the outputs, rank in the organization, years of experience with computers, and the type of hardware used.
Automated SQL documentation using APL2
Authors: Rexford H. Swain
Venue: ACM SIGAPL APL Quote Quad (1991)

An application programmer working with APL2 and SQL/DS will often want to investigate and/or document the definitions of SQL tables and views, particularly when working with tables created by others. Unlike conventional APL file systems, SQL "knows" quite a bit about the objects it is storing, but this information is scattered throughout several system catalogs. An APL2 tool which combines and neatly formats available information about a table is presented.Interpretation of this information may point out conditions which are causing SQL to perform less than optimally. Some issues which influence SQL performance are considered, and some general guidelines for improving performance are suggested.Some familiarity with APL2 and SQL is assumed."SQL" should be understood to mean IBM's SQL/DS for VM systems. But other SQL-based database managers, such as DB2, are very similar.
Power series remainder sequences and Padé fractions over an integral domain
Authors: S. Cabay, P. Kossowski
Venue: Journal of Symbolic Computation (1990)

For univariate power series with coefficients over an integral domain, the notions of power series pseudo-division and power series remainder sequences are introduced and developed. By appealing to the theory of resultants, an algorithm is developed for constructing power series remainder sequences in which the sizes of the coefficients of successive remainders grow linearly, only. The algorithm computes also a co-factor sequence, which is shown to be associated with a given power series remainder sequence. The co-factor sequence yields directly all the Pade fractions along some specific off-diagonal path of the Pade table for a pair of power series (A(z), B(z)). When the sizes of the coefficients of A(z) and B(z) are bounded by k, in the normal case, the algorithm computes Pade fractions of type (m,n) in time O(k^2(m+n)^4). In the abnormal case, and depending on the nature of abnormalities, the time complexity can reach O(k^2(m+n)^5). For computing Pade fractions, the algorithm compares favorably with fraction-free methods, which have a time complexity of O(k^2(m+n)^5), even in the normal case. When applied to polynomials, rather than to power series, the algorithm, for one specific off-diagonal path, corresponds to Euclid's extended algorithm for computing the greatest common divisor of two polynomials.
Selected database research at Stanford
Authors: Arthur Keller, Peter Rathmann, Jeff Ullman, Gio Wiederhold
Venue: ACM SIGMOD Record (1990)

This report describes seven projects at the Computer Science Department of Stanford University that may be relevant to SIGMOD community.
3-D Shape from a Shaded and Textural Surface Image
Authors: Yoonsik Choe, R. L. Kashyap
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1991)

A new 3D texture model is developed by considering the scene image as the superposition of a random texture image on a smooth shaded image. The whole image is analyzed using a patch-by-patch process. Each patch is assumed to be a tilted and slanted texture plane. A modified reflectance map function is applied to describe the deterministic part, and the fractional differencing periodic model is chosen to describe the random texture because of its good performance in texture synthesis and its ability to represent the coarseness and the pattern of the surface at the same time. An orthographical projection technique is developed to deal with this particular random model, which has a nonisotropically distributed texture pattern. For estimating the parameter, a hybrid method that uses both the least square and the maximum-likelihood estimates is applied directly to the given intensity function. By using these parameters, the synthesized image is obtained and used to reconstruct the original image.
Demonstrational Interfaces: A Step Beyond Direct Manipulation
Authors: Brad A. Myers
Venue: Computer (1992)

Demonstrational interfaces, interfaces that let the user perform actions on concrete example objects while constructing an abstract program, thus letting the user create parameterized procedures and objects without learning a programming language, are discussed. The motivations for and problems associated with demonstrational interfaces are presented. A survey of the various types of interfaces is also presented. Areas that would benefit from demonstrational technology, including general-purpose programming, visualization, macros for direct-manipulation interfaces, drawing packages, text editing and formatting, and user interface development environments, are discussed. Research issues involving demonstrational interfaces are reviewed.
Applying Aeatures of IEEE 754 to Sign/Logarithm Arithmetic
Authors: Mark G. Arnold, Thomas A. Bailey, John R. Cowles, Mark D. Winkel
Venue: IEEE Transactions on Computers (1992)

Various features found in standard floating point arithmetic (IEEE 754) are examined in light of their appropriateness for sign/logarithm arithmetic. The emphasis is on a 32-b word size comparable to IEEE 754 single precision, although other word sizes are possible. A multilayer sign/logarithm format is considered. The lowest layer, similar to previous implementations, would provide only normalized representations but would not provide representations for zero, denormalized values, infinities, and NaNs. The highest layer would provide most of the features found in IEEE 754, including zeros, denormalized values, infinities, and NaNs. Novel algorithms for implementing logarithmic denormalized arithmetic are presented. Simulation results show that the error characteristics of the proposed logarithmic denormalized arithmetic algorithms are similar to those of the denormalized floating point arithmetic in IEEE 754.
An Iconic Programming System, HI-VISUAL
Authors: Masahito Hirakawa, Minoru Tanaka, Tadao Ichikawa
Venue: IEEE Transactions on Software Engineering (1990)

A framework for icon management which is quite object-oriented is proposed, and an iconic programming system named HI-VISUAL is presented on the basis of the framework. In the framework, icons represent real objects or concepts already established in a target application environment, whereas icons representing functions are not provided. A function is represented by a combination of two different icons. Each icon can take an active or a passive role against the other. The role sharing is determined dynamically, depending on the environment in which the icons are activated. Programming in HI-VISUAL and implementation issues of the system prototype, now in operation in a laboratory environment, are extensively discussed.
Studies in part of speech labelling
Authors: Marie Meteer, Richard Schwartz, Ralph Weischedel
Venue: Proceedings of the workshop on Speech and Natural Language (1991)

We report here on our experiments with POST (Part of Speech Tagger) to address problems of ambiguity and of understanding unknown words. Part of speech tagging, per se, is a well understood problem. Our paper reports experiments in three important areas: handling unknown words, limiting the size of the training set, and returning a set of the most likely tags for each word rather than a single tag. We describe the algorithms that we used and the specific results of our experiments on Wall Street Journal articles and on MUC terrorist messages.
Techniques for low cost spatial audio
Authors: David A. Burgess
Venue: Proceedings of the 5th annual ACM symposium on User interface software and technology (1992)

There are a variety of potential uses for interactive spatial sound in human-computer interfaces, but hardware costs have made most of these applications impractical. Recently, however, single-chip digital signal processors have made real-time spatial audio an affordable possibility for many workstations. This paper describes an efficient spatialization technique and the associated computational requirements. Issues specific to the use of spatial audio in user interfaces are addressed. The paper also describes the design of a network server for spatial audio that can support a number of users at modest cost.
Semantic optimization: what are disjunctive residues useful for?
Authors: Wolfgang L. J. Kowarschick
Venue: ACM SIGMOD Record (1992)

Residues have been proved to be a very important means for doing semantic optimization. In this paper we will discuss a new kind of residues&mdash;the disjunctive residues. It will be shown that they are very useful to perform subformula elimination, if, in addition, a powerful reduction algorithm is available.
Coping with Erroneous Information While Sorting
Authors: K. B. Lakshmanan, B. Ravikumar, K. Ganesan
Venue: IEEE Transactions on Computers (1991)

The authors study the problem of sorting n distinct elements in ascending sequence according to a total order, using comparison queries which receive 'yes' or 'no' answers, but of which as many as e may be erroneous. In a half-lie version, all 'yes' answers are guaranteed to be correct and the errors are confined to 'no' answers. It is shown that the comparison query complexity of the sorting problem for this case is Omega (n log n+e), and an asymptotically optimal algorithm is demonstrated. In a full-lie version, both 'yes' and 'no' answers can be false. It is shown that the comparison query complexity of the sorting problem for this case is Omega (n log n+en).
Techniques for improving the performance of sparse matrix factorization on multiprocessor workstations
Authors: Edward Rothberg, Anoop Gupta
Venue: Proceedings of the 1990 ACM/IEEE conference on Supercomputing (1990)

In this paper we study the problem of factoring large sparse systems of equations on high-performance multiprocessor workstations. While these multiprocessor workstations are capable of very high peak floating point computation rates, most existing sparse factorization codes achieve only a small fraction of this potential. A major limiting factor is the cost of performing memory accesses. In this paper, we describe a parallel factorization code which utilizes the supernodal structure of the matrix to substantially reduce the number of memory references. We also propose enhancements that significantly reduce the overall cache miss rate. The result is greatly increased factorization performance. We present experimental results from executions on the Silicon Graphics 4D/380 multiprocessor. Using eight processors, the parallel supernodal code achieves a computation rate of approximately 40 MFLOPS when factoring a range of benchmark matrices. This is more than twice as fast as previously used parallel nodal approaches.
Performability Analysis Using Semi-Markov Reward Processes
Authors: G. Ciardo, R. A. Marie, B. Sericola, K. S. Trivedi
Venue: IEEE Transactions on Computers (1990)

M.D. Beaudry (1978) proposed a simple method of computing the distribution of performability in a Markov reward process. Two extensions of Beaudry's approach are presented. The authors generalize the method to a semi-Markov reward process by removing the restriction requiring the association of zero reward to absorbing states only. The algorithm proceeds by replacing zero reward nonabsorbing states by a probabilistic switch; it is therefore related to the elimination of vanishing states from the reachability graph of a generalized stochastic Petri net and to the elimination of fast transient states in a decomposition approach to stiff Markov chains. The use of the approach is illustrated with three applications.
An undergraduate project to compute minimal perfect hashing functions
Authors: John A. Trono
Venue: ACM SIGCSE Bulletin (1992)

Some heuristics for computing the character weights in a Cichelli-style, minimal perfect hashing function are given. These ideas should perform best when applied to relatively small, static sets of character strings and they can be used as the foundation for a large programming assignment. An example using the names of the fifty United States is given to illustrate how the weights are determined.
Genetic algorithms
Authors: Manuel Alfonseca
Venue: Proceedings of the international conference on APL '91 (1991)

Genetic algorithms, invented by J. H. Holland, emulate biological evolution in the computer and try to build programs that can adapt by themselves to perform a given function. In some sense, they are analogous to neural networks, but there are important differences between them. This paper shows that genetic algorithms are easy to program, test and analyze by means of APL2 functions.
BBN HARC and Delphi results on the ATIS benchmarks&mdash;February 1991
Authors: S. Austin, D. Ayuso, M. Bates, R. Bobrow, R. Ingria, J. Makhoul, P. Placeway, R. Schwartz, D. Stallard
Venue: Proceedings of the workshop on Speech and Natural Language (1991)

This paper presents the test results of running BBN's HARC spoken language system and DELPHI natural language understanding system on the ATIS benchmarks.We give a brief system overview, and review the major changes that have been made in Delphi since the last DARPA SLS workshop. We will briefly discuss the development and training process, and then present our test results and an analysis of their meaning.
A calculus for overloaded functions with subtyping
Authors: Giuseppe Castagna, Giorgio Ghelli, Giuseppe Longo
Venue: ACM SIGPLAN Lisp Pointers (1992)

We present a simple extension of typed &lgr;-claculus where functions can be overloaded by adding different &ldquo;pieces of code&rdquo;. In short, the code of an overloaded function is formed by several branches of code; the branch to execute is chosen, when the function is applied, according to a particular selection rule which depends on the type of the argument. The crucial feature of the present approach is that a subtyping relation is defied among types, such that the type of a term generally decreases during computation, and this fact induces a distinction between the &ldquo;compile-time&rdquo; type and the &ldquo;run-time&rdquo;type of a term. We study the case of overloaded functions where the branch selection depends on the run-time type of the argument, so that overloading cannot be eliminated by a static analysis of code, but is an essential feature to be dealt with during computation. We prove Confluence and Strong Normalization for this calculus as well as a generalized Subject-Reduction theorem (but proofs are ommitted in this abstract. The definition of this calculus is driven by the understanding of object-oriented features and the connections between our calculus and object-orientedness are extensively stressed. We show that this calculus provides a foundation for typed object-oriented languages which solves some of the problems of the standard record-based approach. It also provides a type-discipline for a relevant fragment of the &ldquo;core framework&rdquo; of CLOS.
Lexico-semantic pattern matching as a companion to parsing in text understanding
Authors: Paul S. Jacobs, George R. Krupka, Lisa F. Rau
Venue: Proceedings of the workshop on Speech and Natural Language (1991)

Ordinarily, one thinks of the problem of natural language understanding as one of making a single, left-to-right pass through an input, producing a progressively refined and detailed interpretation. In text interpretation, however, the constraints of strict left-to-right processing are an encumbrance. Multi-pass methods, especially by interpreting words using corpus data and associating units of text with possible interpretations, can be more accurate and faster than single-pass methods of data extraction. Quality improves because corpus-based data and global context help to control false interpretations; speed improves because processing focuses on relevant sections.The most useful forms of pre-processing for text interpretation use fairly superficial analysis that complements the style of ordinary parsing but uses much of the same knowledge base. Lexico-semantic pattern matching, with rules that combine lexical analysis with ordering and semantic categories, is a good method for this form of analysis. This type of pre-processing is efficient, takes advantage of corpus data, prevents many garden paths and fruitless parses, and helps the parser cope with the complexity and flexibility of real text.
The robot localization problem in two dimensions
Authors: Leonidas J. Guibas, Rajeev Motwani, Prabhakar Raghavan
Venue: Proceedings of the third annual ACM-SIAM symposium on Discrete algorithms (1992)

We consider the following problem: given a simple polygon P and a star-shaped polygon V, find a point (or the set of points) in P from which the portion of P that is visible is congruent to V. The problem arises in the localization of robots using a range-finder&mdash;P is a map of a known environment, V is the portion visible from the robot's position, and the robot must use this information to determine its position in the map. We give a scheme that preprocesses P so that any subsequent query V is answered in optimal time O(m + log n + A), where m and n are the number of vertices in V and P, and A is the number of points in P that are valid answers (the output size). Our technique allows us to trade off smoothly between the query time and the preprocessing time or space. We also devise a data structure for output-sensitive determination of the visibility polygon of a query point inside a polygon P. We then consider a variant of the localization problem in which there is a maximum distance to which the robot can &ldquo;see&rdquo;&mdash;this is motivated by practical considerations, and we outline a similar solution for this case. We also show that a single localization query V can be answered in time O(mn) with no preprocessing.
From Washington: CEOs unite to influence U.S. technology policy
Authors: Diane Crawford
Venue: Communications of the ACM (1991)

Verbal sparring over U.S. technology policy has persisted unabated for over one decade and two presidential administrations. As politicians, academicians, and industry representatives continue to volley policy virtues, the nation has watched its strong lead in the world's technology tournament slip another few notches. Industry observers lament that setting priorities, particularly in terms of R D spending, has reached a turning point.
On parallel complexity of integer linear programming, GCD and the iterated mod function
Authors: Yu Lin-Kriz, Victor Pan
Venue: Proceedings of the third annual ACM-SIAM symposium on Discrete algorithms (1992)

We study parallel computational methods for integer linear programming problem with two variables. Applying several novel techniques, we prove that this problem is NC-equivalent to computing the continued fraction expansion of a rational number, that is, to computing all the intermediate remainders in the Euclidean algorithm applied to two integers, plus to computing the output of an iterated modulo function, with the remainder sequence from the Euclidean algorithm (that is, with the continued fraction expansion of a rational number) as its input arguments. The best previously known results are special cases of our theorem.
Abstractions of Finite-State Machines and Immediately-Detectable Output Faults
Authors: Kostas N. Oikonomou
Venue: IEEE Transactions on Computers (1992)

A general way to make a smaller model of a large system, or to represent the fact that the observations possible on it are limited, is to apply an abstraction A to it. If the system is modeled by a finite-state machine M, the abstraction consists of three partitions, one for each of the state, input, and output sets. States, inputs, or outputs lumped together in one block by the partition are indistinguishable from each other, resulting in a nondeterministic machine M/sub A/. An observer of M/sub A/, whose task is to detect erroneous behavior in M, is prevented by the abstraction from seeing some of the faults. The authors investigate the choice of an abstraction that is optimal with respect to immediately detectable faults in the output map. It is shown that this requires solving an NP-complete 'set-partitioning' problem. A polynomial-time algorithm for finding an approximately optimal partition of either the states or the inputs of M, together with a way to check the goodness of the approximation is given. This algorithm also solves the undetectable fault minimization problem exactly, and in polynomial time.