ppxscal/embedding_network huggingface dataset:
Stochastic sampling in computer graphics
Authors: Robert L. Cook
Venue: ACM Transactions on Graphics (TOG) (1986)

Ray tracing, ray casting, and other forms of point sampling are important techniques in computer graphics, but their usefulness has been undermined by aliasing artifacts. In this paper it is shown that these artifacts are not an inherent part of point sampling, but a consequence of using regularly spaced samples. If the samples occur at appropriate nonuniformly spaced locations, frequencies above the Nyquist limit do not alias, but instead appear as noise of the correct average intensity. This noise is much less objectionable to our visual system than aliasing. In ray tracing, the rays can be stochastically distributed to perform a Monte Carlo evaluation of integrals in the rendering equation. This is called distributed ray tracing and can be used to simulate motion blur, depth of field, penumbrae, gloss, and translucency.
Moving a ladder in three dimensions: upper and lower bounds
Authors: Y. Ke, J. O'Rourke
Venue: Proceedings of the third annual symposium on Computational geometry (1987)

This paper summarizes two results in motion planning, the details of which are in two technical reports. The first establishes an &OHgr;(n4) lower bound on moving a ladder (a line segment) in three dimensions in the presence of polyhedral obstacles with a total of n vertices. This bound is established via a complex arrangement of polygons in space that force a ladder to make &OHgr;(n4 distinct moves between particular initial and final positions. The second report establishes an &Ogr; (n6logn) upper bound by exhibiting an algorithm with that time complexity. The algorithm uses the cell decomposition approach pioneered by Schwartz and Sharir. We suspect that the lower bound is closer to the true complexity of the problem.
Managing the user services function
Authors: James M. Pruett, Paul J. Setze
Venue: Proceedings of the 15th annual ACM SIGUCCS conference on User Services (1987)

Over the years, a great deal has been written about performing the various functions of user services. Last year's conference in Montreal focused on a variety of topics, ranging from microcomputer support to supercomputer support and from online documentation to desktop publishing. As we&mdash;two &ldquo;managers&rdquo; of user services&mdash;watched, listened, read, and discussed the content and progress of the conference, it seemed to us that one key topic was missing: a discussion of the problems, concerns, and approaches to actually managing the multi-faceted user services function. Since many of the conference's attendees were themselves managers, we thought that a session on &ldquo;managing user services&rdquo; could be truly helpful. At that time, we decided to put together our collective views on the user services management process&mdash;not because our views are particularly unique or because we think we have all of the answers, but because we have thought about and lived the process (which may help others) and because we would like to hear other views on the process (which may help us). The paper has been divided into six major topics of discussion: Overview, Internal Organization, Mandatory Internal Functions, Classical Functions, Other Ways to Serve Users, and Concerns. Each of us, user services managers at two distinctly different universities in two different parts of the United States, has addressed each topic from our organization's perspective.
Spatial query processing in an object-oriented database system
Authors: Jack A. Orenstein
Venue: ACM SIGMOD Record (1986)

DBMSs must offer spatial query processing capabilities to meet the needs of applications such as cartography, geographic information processing and CAD. Many data structures and algorithms that process grid representations of spatial data have appeared in the literature. We unify much of this work by identifying common principles and distilling them into a small set of constructs. (Published data structures and algorithms can be derived as special cases.) We show how these constructs can be supported with only minor modifications to current DBMS implementations. The ideas are demonstrated in the context of the range query problem. Analytical and experimental evidence indicates that performance of the derived solution is very good (e.g., comparable to performance of the kd tree.)
Analytic Queueing Network Models for Parallel Processing of Task Systems
Authors: A Thomasian, P F Bay
Venue: IEEE Transactions on Computers (1986)

This paper is concerned with the performance evaluation of a realistic model of parallel computations. We present an efficient algorithm to determine the mean completion time and related performance measures for a task system: a set of tasks with precedence relationships in their execution sequence, such that the resulting graph is acyclic. A queueing network (QN) is used to model tasks executing on a single or multicomputer system. In the case of multicomputer systems, we take into account the delay due to interprocess communication. A straight- forward application of a QN solver to the problem is not possible due to variations in the state of the system (composition of tasks in execution). An accurate algorithm based on hierarchical decomposition is presented for solving task systems. At the higher level, the system behavior is specified by a Markov chain whose states correspond to the combination of tasks in execution. The state transition rate matrix for the Markov chain is triangular (since the task system graph was assumed to be acyclic), therefore it can be solved efficiently to compute the state probabilities and the task initiation/completion times. At the lower level, the transition rates among the states of the Markov chain are computed using a QN solver, which determines the throughput of the computer system for each system state. The model and the solution method can be used in performance evaluation of applications exhibiting concurrency in centralized/distributed systems where there are conflicting goals of load balancing and minimizing interprocess communication overhead.
Data flow analysis for `intractable' system software
Authors: Harold Johnson
Venue: ACM SIGPLAN Notices (1986)

We describe, and give experience with, a new method of intraprocedural data flow analysis on reducible flow-graphs[9]. The method is advantageous in imbedded applications where the added value of improved performance justifies substantial optimization effort, but extremely powerful data flow analysis is required due to the code profile.The method is unusual in that (1) various kinds of forward data flow analysis are done simultaneously, so that benefit is derived from informative interactions (e.g. between constant propagation[7] and alias analysis[8]) and (2) we abandon insistence on reaching a least fixed point, allowing us to handle extremely broad classes of information (e.g., inequality of array indices, which implies non-aliasing in array references).We argue that the gain from using a very rich framework more than offsets the loss due to non-minimal fixed points, and justify this with a 'thought experiment' and practical results.
The complexity of propositional linear temporal logics
Authors: A. P. Sistla, E. M. Clarke
Venue: Journal of the ACM (JACM) (1985)

The complexity of satisfiability and determination of truth in a particular finite structure are considered for different propositional linear temporal logics. It is shown that these problems are NP-complete for the logic with F and are PSPACE-complete for the logics with F, X, with U, with U, S, X operators and for the extended logic with regular operators given by Wolper.
Concepts and experiments in computational reflection
Authors: Pattie Maes
Venue: ACM SIGPLAN Notices (1987)

This paper brings some perspective to various concepts in computational reflection. A definition of computational reflection is presented, the importance of computational reflection is discussed and the architecture of languages that support reflection is studied. Further, this paper presents a survey of some experiments in reflection which have been performed. Examples of existing procedural, logic-based and rule-based languages with an architecture for reflection are briefly presented. The main part of the paper describes an original experiment to introduce a reflective architecture in an object-oriented language. It stresses the contributions of this language to the field of object-oriented programming and illustrates the new programming style made possible. The examples show that a lot of programming problems that were previously handled on an ad hoc basis, can in a reflective architecture be solved more elegantly.
An efficient augmented-context-free parsing algorithm
Authors: Masaru Tomita
Venue: Computational Linguistics (1987)

An efficient parsing algorithm for augmented context-free grammars is introduced, and its application to on-line natural language interfaces discussed. The algorithm is a generalized LR parsing algorithm, which precomputes an LR shift-reduce parsing table (possibly with multiple entries) from a given augmented context-free grammar. Unlike the standard LR parsing algorithm, it can handle arbitrary context-free grammars, including ambiguous grammars, while most of the LR efficiency is preserved by introducing the concept of a "graph-structured stack". The graph-structured stack allows an LR shift-reduce parser to maintain multiple parses without parsing any part of the input twice in the same way. We can also view our parsing algorithm as an extended chart parsing algorithm efficiently guided by LR parsing tables. The algorithm is fast, due to the LR table precomputation. In several experiments with different English grammars and sentences, timings indicate a five- to tenfold speed advantage over Earley's context-free parsing algorithm.The algorithm parses a sentence strictly from left to right on-line, that is, it starts parsing as soon as the user types in the first word of a sentence, without waiting for completion of the sentence. A practical on-line parser based on the algorithm has been implemented in Common Lisp, and running on Symbolics and HP AI workstations. The parser is used in the multi-lingual machine translation project at CMU. Also, a commercial on-line parser for Japanese language is being built by Intelligent Technology Incorporation, based on the technique developed at CMU.
A Computer Algorithm for Minimizing Reed-Muller Canonical Forms
Authors: H. Fleisher, M. Tavel, J. Yeager
Venue: IEEE Transactions on Computers (1987)

A computer algorithm is presented that uses geometrical operations to minimize multioutput Reed-Muller expansions of up to ten variables.
Integrated concurrency control and recovery mechanisms: design and performance evaluation
Authors: Rakesh Agrawal, David J. Dewitt
Venue: ACM Transactions on Database Systems (TODS) (1985)

In spite of the wide variety of concurrency control and recovery mechanisms proposed during the past decade, the behavior and the performance of various concurrency control and recovery mechanisms remain largely not well understood. In addition, although concurrency control and recovery mechanisms are intimately related, the interaction between them has not been adequately explored. In this paper, we take a unified view of the problems associated with concurrency control and recovery for transaction-oriented multiuser centralized database management systems, and we present several integrated mechanisms. We then develop analytical models to study the behavior and compare the performance of these integrated mechanisms, and we present the results of our performance evaluation.
Encapsulation and inheritance in object-oriented programming languages
Authors: Alan Snyder
Venue: Conference proceedings on Object-oriented programming systems, languages and applications (1986)

Object-oriented programming is a practical and useful programming methodology that encourages modular design and software reuse. Most object-oriented programming languages support data abstraction by preventing an object from being manipulated except via its defined external operations. In most languages, however, the introduction of inheritance severely compromises the benefits of this encapsulation. Furthermore, the use of inheritance itself is globally visible in most languages, so that changes to the inheritance hierarchy cannot be made safely. This paper examines the relationship between inheritance and encapsulation and develops requirements for full support of encapsulation with inheritance.
A methodology for synthesis of recursive functional programs
Authors: Debasish Banerjee
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1987)

John Backus introduced the Functional Programming (FP) system, the variable-free applicative system having reduction semantics. Backus has also introduced a unique expansion technique for reasoning about a class of recursive FP programs. As a natural outgrowth of this expansion technique, an FP program synthesis methodology is described in this paper. The methodology synthesizes recursive FP programs of the form f = p &rarr;, q; E(f . h) from their preformulated case-by-case descriptions, which in turn come from given input-output example specifications. After explaining the methodology informally, formalization in the form of a definition and a synthesis theorem is introduced. A sufficient condition for the functional form E, for successful synthesis under the present methodology, is obtained structurally. Several illustrative examples of synthesis are also included.
Traffic-Specific Interconnection Networks for Multicomputers
Authors: K. M. Nichols, D. G. Messerschmitt
Venue: IEEE Transactions on Computers (1987)

Special-purpose networks of processors and intelligent switching devices can be programmed to solve problems with inherent parallelism. The target algorithm is coded into a number of asynchronously executing parallel tasks, and assigned to specific processors. For well-known algorithms, information about the data communicated between these tasks (traffic) can be characterized and used by a heuristic algorithm to produce a specialized interconnection network of switching devices at a lower cost and increased performance over the use of a general purpose structure. A program was developed which uses intertask communications to automatically generate interconnection structures of switch chips (SC's). Simulation results were used to compare cost/performance measures for the program-generated networks with some well-known structures, using both statistically generated traffic patterns and the simulation of real applications.
Spaceprobe: A system for representing complex knowledge
Authors: J Dinsmore
Venue: Proceedings of the ACM SIGART international symposium on Methodologies for intelligent systems (1986)

Spaceprobe is an experimental system for representing and reasoning about such things as beliefs, wants, fictions, hypotheses (both possibilities and counterfactuals), situations, generalizations, and time in a uniform and principled way. It is based on the theory of Knowledge Partitioning and Simulative Reasoning [2, 4, 5].
Experimental analysis of layered Ethernet software
Authors: B. Bhargava, T. Mueller, J. Riedl
Venue: Proceedings of the 1987 Fall Joint Computer Conference on Exploring technology: today and tomorrow (1987)

We conducted a series of experiments contrasting the performance of a standard communications protocol with the performance of modified versions of the protocol. The results of these experiments divide the communications delay in Sun's implementation of UDP/IP on a 10 megabit per second Ethernet into categories such as buffer copying, context switching, protocol layering, internet address translation, and checksum computation. We also describe the implementation of our own simple Ethernet protocol which propagates messages in slightly less than half the time required by UDP/IP. Our experimental results indicate that the most expensive of these are socket layering and connection, even though most of the layering in the UDP/IP implementation is incidental to the protocol.
On designing for usability: an application of four key principles
Authors: T. T. Hewett, C. T. Meadow
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems (1986)

In a recent paper, Gould and Lewis (1983a) argued for the importance of four key principles in computer system design. These principles are: early focus on users, interactive design, empirical measurement, and iterative design. Gould and Lewis also express their belief that these principles are essential to successful design and refer to an example of their use (Gould and Lewis, 1983b). It is the purpose of this paper to report another example of how these principles played a major role and proved their worth in the design of a successful system.
Architecture and implementation of the Darmstadt database kernel system
Authors: H. B. Paul, H. J. Schek, M. H. Scholl
Venue: ACM SIGMOD Record (1987)

The multi-layered architecture of the DArmStadt Data Base System (DASDBS) for advanced applications is introduced DASDBS is conceived as a family of application-specific database systems on top of a common database kernel system. The main design problem considered here is, What features are common enough to be integrated into the kernel and what features are rather application-specific? Kernel features must be simple enough to be efficiently implemented and to serve a broad class of clients, yet powerful enough to form a convenient basis for application-oriented layers. Our kernel provides mechanisms to efficiently store hierarchically structured complex objects, and offers operations which are set-oriented and can be processed in a single scan through the objects. To achieve high concurrency in a layered system, a multi-level transaction methodology is applied. First experiences with our current implementation and some lessons we have learned from it are reported.
Computers and society: a liberal arts perspective
Authors: Ellen Cunningham
Venue: Proceedings of the seventeenth SIGCSE technical symposium on Computer science education (1986)

There is ambivalence among computer science educators regarding the degree to which ethical and value questions should be incorporated in the computer science curriculum. This paper states a philosophical case for substantive treatment of these topics in colleges committed to the liberal arts, and goes on to consider some of the practical difficulties involved.
The Generalized Gabor Scheme of Image Representation in Biological and Machine Vision
Authors: Moshe Porat, Yehoshua Y. Zeevi
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1988)

A scheme suitable for visual information representation in a combined frequency-position space is investigated through image decomposition into a finite set of two-dimensional Gabor elementary functions (GEF). The scheme is generalized to account for the position-dependent Gabor-sampling rate, oversampling, logarithmic frequency scaling and phase-quantization characteristic of the visual system. Comparison of reconstructed signal highlights the advantages of the generalized Gabor scheme in coding typical bandlimited images. It is shown that there exists a tradeoff between the number of frequency components used per position and the number of such clusters (sampling rate) utilized along the spatial coordinate.
An extension to the relational model for indefinite databases
Authors: K.-C. Liu, R. Sunderraman
Venue: Proceedings of the 1987 Fall Joint Computer Conference on Exploring technology: today and tomorrow (1987)

This paper presents an extension to the relational model to represent indefinite/disjunctive and &ldquo;maybe&rdquo; information, in addition to the definite information, within relations. The semantics of the generalized relational algebraic operators are precisely defined. Answers to queries expressed as a combination of the extended relational operators may contain, in addition to definite, indefinite and maybe information that may be useful in many applications. Also discussed are certain optimization strategies and the effect of functional dependencies on updates to the database.
A Prolog model of the income tax act of Canada
Authors: D. M. Sherman
Venue: Proceedings of the 1st international conference on Artificial intelligence and law (1987)

The use of computers in Canadian tax planning has until now been concentrated on numerical analysis. The computer is indeed an excellent tool for calculating tax effects where the legal results of transactions are known. However, I maintain that it can be equally useful as a tool for analysing transactions to determine what those legal results are. The complexities of the Canadian tax system are such that a given transaction could have unintended tax results, where the facts resulting from the transaction fit the words of a rule which may have been designed for, and is perceived as applying to, different circumstances altogether. In this paper I consider the structure and form of the Income Tax Act and show how it is well-designed for computerization. I then review the primary design considerations for a computer-based tax planning system. Finally, I describe the implementation of a partial tax analysis system which I have programmed in Prolog, and review its deficiencies and the extensions which would be required to make it a useful planning tool for tax practitioners. NOTE: this paper is a greatly condensed version of a Master of Laws (LL.M.) thesis, &ldquo;Blueprint for a Computer-Based Model of the Income Tax Act of Canada&rdquo;, York University, September 1986. Important detail, references and examples have been omitted due to lack of space. Interested readers are invited to contact the author for a copy of the thesis.
The world's fastest Scrabble program
Authors: Andrew W. Appel, Guy J. Jacobson
Venue: Communications of the ACM (1988)

An efficient backtracking algorithm makes possible a very fast program to play the SCRABBLE&reg; Brand Crossword Game. The efficiency is achieved by creating data structures before the backtracking search begins that serve both to focus the search and to make each step of the search fast.
Answering queries on embedded-complete database schemes
Authors: Edward P. F. Chan, Alberto O. Mendelzon
Venue: Journal of the ACM (JACM) (1987)

It has been observed that, for some database schemes, users may have difficulties retrieving correct information, even for simple queries. The problem occurs when some implicit &ldquo;piece&rdquo; of information, defined on some subset of a relation scheme, is not explicitly represented in the database state. In this situation, users may be required to know how the state and the constraints interact before they can retrieve the information correctly. In this paper, the formal notion of embedded-completeness is proposed, and it is shown that schemes with this property avoid the problem described above. A polynomial-time algorithm is given to test whether a database scheme is independent and embedded-complete. Under the assumption of independence, it is shown that embedded-complete schemes allow efficient computation of optimal relational algebra expressions equivalent to the X-total projection, for any set of attributes X.