ppxscal/embedding_network huggingface dataset:
Searching for semantics
Authors: John Hannan
Venue: Proceedings of the 1993 ACM SIGPLAN symposium on Partial evaluation and semantics-based program manipulation (1993)

We consider the task of generating operational semantics, defined as axiomatizations of relations such as e &rarr; v, from an equality theory, given as a set of equations {e1 = e2}. We generate these semantics by constructing derived rules based on equations provable in this equality theory and constrained by a simple correctness criteria. This criteria, which we have previously used in verifying compiler correctness, states that the generated semantics correctly implements a given source language. We use Elf, a logic programming language, to axiomatize source language semantics, equality theories for target languages, and translations between source and target languages, and to construct the derived rules, based on these axiomatizations, for the target languages. During the process of constructing derived rules we simultaneously construct a correctness proof, relating these new rules to a given source language and the translation between languages. Previous uses of Elf (in compiler construction and language manipulation) have focused on the language's type system to express statements of correctness. We focus here on Elf's search paradigm, exploiting it in a crucial way to construct objects representing semantic specifications. We have only considered operational semantics for simple functional languages, but we expect that our results can be generalized to a wider class of languages.
Document recognition: concepts and implementations
Authors: Nenad Marovac
Venue: ACM SIGOIS Bulletin (1992)

Document recognition is a task in which a document in its physical presentation format is transformed into a structured author-oriented model of the document. The presentation format can be bitmaps of document pages, a description of the document in a Page Description Language (PDL), or encoding of the document in a printer or graphics language. The structured model is a format allowing for addition to the document, manipulation of the document, and reformating the layout and the output appearance of the document.Fully automatic document recognition is not possible, in general, for the same reason that it is not possible to de-translate computer programs automatically. However, it is possible to develop a man-assisted semi-automatic document recognition method. This method uses two passes. The first pass is completely automatic; it produces a document format called Interactive Document Model. The Interactive Document Model comprises recognized typesetting and descriptive structures together with derived ODA logical and layout structures for the document. The model generated in the first pass is enough for most purposes and applications. However, if it is not acceptable, the user can then enter the second pass and interactively edit the logical structure.This paper has three objectives. The first is to formalize the concept of document recognition. The second is to subdivide the problem of document recognition and classify it into a number of subproblems, each dealing with different aspects of the problem. The third objective is to introduce a problem which we wish to solve, and then to present a High Level Document Recognition method and the experience in developing and using a number of implementations of the method.
A general abstract representation for the study of concurrent programs
Authors: Sudharsan R. Iyengar, Narayan C. Debnath
Venue: Proceedings of the 1993 ACM conference on Computer science (1993)

In this paper we propose an abstract representation, called Synchronized Generalized Program Graph (SGPG), for concurrent programs. SGPG incorporates the data dependencies, control flow, control dependencies, communication, and synchronization primitives of the concurrent program it represents. The features of SGPG and the process of its construction are outlined. Algorithms for generating the SGPG representation of an imperative concurrent programs are discussed in detail. The producer consumer problem is used as an illustrative example. SGPG can be used for the study and analysis of concurrent programs, research involving the implementation, testing, measurement of cognitive complexity, and for proving correctness of concurrent programs.
A mathematical model of the finding of usability problems
Authors: Jakob Nielsen, Thomas K. Landauer
Venue: Proceedings of the INTERACT '93 and CHI '93 conference on Human factors in computing systems (1993)

For 11 studies, we find that the detection of usability problems as a function of number of users tested or heuristic evaluators employed is well modeled as a Poisson process. The model can be used to plan the amount of evaluation required to achieve desired levels of thoroughness or benefits. Results of early tests can provide estimates of the number of problems left to be found and the number of additional evaluations needed to find a given fraction. With quantitative evaluation costs and detection values, the model can estimate the numbers of evaluations at which optimal cost/benefit ratios are obtained and at which marginal utility vanishes. For a &ldquo;medium&rdquo; example, we estimate that 16 evaluations would be worth their cost, with maximum benefit/cost ratio at four.
Matroid Shellability, &beta;-Systems, and Affine Hyperplane Arrangements
Authors: Günter M. Ziegler
Venue: Journal of Algebraic Combinatorics: An International Journal (1992)

The broken-circuit complex is fundamental to the shellability and homology of matroids, geometric lattices, and linear hyperplane arrangements. This paper introduces and studies the &beta;-system of a matroid, &beta;nbc(M), whose cardinality is Crapo's &beta;-invariant. In studying the shellability and homology of base-pointed matroids, geometric semilattices, and afflne hyperplane arrangements, it is found that the &beta;-system acts as the afflne counterpart to the broken-circuit complex. In particular, it is shown that the &beta;-system indexes the homology facets for the lexicographic shelling of the reduced broken-circuit complex \overline {\rm BC}(M), and the basic cycles are explicitly constructed. Similarly, an EL-shelling for the geometric semilattice associated with M is produced,_and it is shown that the &beta;-system labels its decreasing chains. Basic cycles can be carried over from \overline {\rm BC}(M) The intersection poset of any (real or complex) afflne hyperplane arrangement \cal A is a geometric semilattice. Thus the construction yields a set of basic cycles, indexed by &beta;nbc(M), for the union \bigcup \cal A of such an arrangement.
Effects of nonsymmetric release times on rate monotonic scheduling
Authors: Randall G. Karl, T. Leo Lo, Daniel C. St. Clair
Venue: Proceedings of the 1993 ACM conference on Computer science (1993)

This paper discusses problems associated with scheduling periodic tasks on a uniprocessor in a hard, real-time processing environment using a static-priority, preemptive-resume operating system. The scheduling problems associated with a task set containing a single periodic task which has two fixed release periods of unequal length are examined. Some real-world applications may require task release times which are periodic, but whose tasking periods are not symmetric. A scheduling algorithm for task sets with a single nonsymmetric task was developed for static-priority, preemptive-resume operating systems. The nonsymmetric scheduling algorithm is based on the rate monotonic scheduling algorithm which assigns higher task priorities to tasks with shorter release periods. The effects on processor utilization using two different priority assignment schemes are examined. The first method sorts the task priorities by the average release periods. The second method sorts the task priorities using the short nonsymmetric task period with the average period lengths for the remaining tasks. A large number of task sets were generated to characterize effects of the two priority assignment methods on task set utilization levels when used with the nonsymmetric scheduling algorithm. Characterization results for the two methods indicated that the short nonsymmetric task period priority assignment had higher breakdown utilizations than the average period priority assignment method. For task sets with a low utilization nonsymmetric task, use of the short period priority assignment method resulted in little or no loss in the overall task set breakdown utilization. Maximizing the processor utilization is desirable, provided the tasks operate in a deterministic manner and meet their deadlines. The nonsymmetric scheduling algorithm allows the system designer to calculate the feasibility of a task set containing a nonsymmetric period task.
A second generation user interface design environment: the model and the runtime architecture
Authors: Piyawadee Sukaviriya, James D. Foley, Todd Griffith
Venue: Proceedings of the INTERACT '93 and CHI '93 conference on Human factors in computing systems (1993)

Several obstacles exist in the user interface design process which distract a developer from designing a good user interface. One of the problems is the lack of an application model to keep the designer in perspective with the application. The other problem is having to deal with massive user interface programming to achieve a desired interface and to provide users with correct help information on the interface. In this paper, we discuss an application model which captures information about the application to specifications of a desired interface. The application model is then used to control the dialogues at runtime and can be used by a help component to automatically generate animated and textual help. Specification changes in the application model will automatically result in behavioral changes in the interface.
Incremental database systems: databases from the ground up
Authors: Stanley B. Zdonik
Venue: ACM SIGMOD Record (1993)

This paper discusses a new approach to database management systems that is better suited to a wide class of new applications such as scientific, hypermedia, and financial applications. These applications are characterized by their need to store large amounts of raw, unstructured data. Our premise is that, in these situations, database systems need a way to store data without imposing a schema, and a way to provide a schema incrementally as we process the data. This requires that the raw data be mapped in complex ways to an evolving schema.
Can Datalog be approximated?
Authors: Surajit Chaudhuri, Phokion G. Kolaitis
Venue: Proceedings of the thirteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1994)

In this paper, we investigate whether recursive Datalog predicates can be approximated by finite unions of conjunctive queries. We introduce a quantitative notion of error and examine two types of approximation, namely, absolute approximation and relative approximation. We also stipulate that the approximations obey certain qualitative criteria, namely we require them to be upper envelopes or lower envelopes of the Datalog predicate they approximate. We establish that absolute approximation by finite unions of conjunctive queries is not possible, which means that no unbounded Datalog predicate can be approximated by a finite union of conjunctive queries in such a way that the error is bounded uniformly by the same constant on all finite databases. After this, we examine relative approximations, i.e., approximations that guarantee bounds for the error relative to the size of the Datalog predicate under consideration. Although such approximations exist in some cases, we show that for several large and well-studied classes of unbounded Datalog predicates it is not possible to find finite unions of conjunctive queries that satisfy the aforementioned qualitative criteria and have the property that the relative error of the approximation is bounded by a constant. Finally, we consider first-order approximations and obtain sharp negative results for the approximability of the transitive closure query and the cycle query by first-order queries.
Generalized hidden surface removal
Authors: Mark de Berg
Venue: Proceedings of the ninth annual symposium on Computational geometry (1993)

In this paper we study the following generalization of the classical hidden surface removal problem: given a set S of objects, a view point and a point light source, compute which parts of the objects in S are visible, subdivided into parts that are lit and parts that are not lit. We prove tight bounds on the maximum combinatorial complexity of such views and give efficient output-sensitve algorithms to compute the views for three cases: (i) S consists of non-intersecting triangles, (ii) S consists of horizontal axis-parallel rectangles, (iii) S is the set of faces of a polyhedral terrain.
An O(nlogn) algorithm for finding minimal path cover in circular-arc graphs
Authors: Y. Daniel Liang, G. K. Manacher
Venue: Proceedings of the 1993 ACM conference on Computer science (1993)

Whether there exists a polynomial algorithm for the minimal path cover problem in circular-arc graphs remains open. In this paper, we present a polynomial time algorithm for finding a minimal path cover for a set of n arcs in a circular-arc model. Our algorithm takes &Ogr;(nlogn) time.
Processor autonomy on SIMD architectures
Authors: P. J. Narayanan
Venue: Proceedings of the 7th international conference on Supercomputing (1993)

Flynn classified high speed (parallel) computers into four categories. Of these, the single instruction stream, multiple data stream (SIMD) processor array machines have become very popular in practical parallel processing. The commercially available processor array machines display important architectural variety, while belonging to SIMD category of machines. In this paper, we further categorize the SIMD class of machines on the basis of processor autonomy of the machines, which is the capability of the individual processing elements (PEs) to act autonomously in some significant way. For each autonomy class, we provide examples and illustrate some of its important algorithmic features. We also discuss how each type of autonomy can be simulated on machines without it. We study the addressing autonomous class of machines in greater detail by discussing three algorithms on machines with and without that type of autonomy. A discussion on how processor autonomy appears in algorithms in the literature and what impact they can have in the future machines also is provided.
Memory management in Ada83 and Ada9X
Authors: Stef Van Vlierberghe
Venue: ACM SIGAda Ada Letters (1994)

There has been a significant evolution in the design of Ada9X with respect to meeting memory management requirements. This paper will introduce the memory management problem, and possible approaches in Ada83 and Ada9X. Today the Committee Draft includes full support for user-defined assignment and finalization, and this paper will illustrate how the new language features can be used to provide solutions that are both elegant and robust.An example of a primitive list component is used to illustrate the problem, and to illustrate the evolution from Ada83 to Ada9X.
Empirically-based re-design of a hypertext encyclopedia
Authors: Keith Instone, Barbee Mynatt Teasley, Laura Marie Leventhal
Venue: Proceedings of the INTERACT '93 and CHI '93 conference on Human factors in computing systems (1993)

This paper reports on the processes used and guidelines discovered in re-designing the user interface of the hypertext encyclopedia, HyperHolmes. The re-design was based on the outcomes of a previous experiment and was evaluated experimentally. Results showed that the new system resulted in superior performance and somewhat different styles of navigation compared to the old system and to paper. The study provides empirical support for design guidelines relating to tiled windows, navigation tools, graphics and hierarchical navigation.
Does CASE make the customer happier
Authors: Robert McLaughlin
Venue: ACM SIGSOFT Software Engineering Notes (1993)

CASE technology is and will change the nature of software development. It is often haled as the thing that will save our industry. It is however just another tool. Just as a good hammer in the hands of a bad carpenter will make a house that collapses, CASE in the hands of a fool will save no one.
Integrating theoreticians' and practitioners' perspectives with design rationale
Authors: Victoria Bellotti
Venue: Proceedings of the INTERACT '93 and CHI '93 conference on Human factors in computing systems (1993)

QOC design rationale represents argumentation about design alternatives and assessments. It can be used to generate design spaces which capture and integrate information from design discussions and diverse kinds of theoretical analyses. Such design spaces highlight how different theoretical approaches can work together to help solve design problems. This paper describes an example of the generation of a multi-disciplinary QOC design space which shows how designers' deliberations can be augmented with design contributions from a combination of different theoretical HCI approaches.
Preference-based decision making for cooperative knowledge-based systems
Authors: Stephen T. C. Wong
Venue: ACM Transactions on Information Systems (TOIS) (1994)

Recent advances in cooperative knowledge-based systems (CKBS) offer significant promise for intelligent interaction between multiple AI systems for solving larger, more complex problems. In this paper, we propose a logical, qualitative problem-solving scheme for CKBS that uses social choice theory as a formal basis for making joint decisions and promoting conflict resolution. This scheme consists of three steps: (1) the selection of decision criteria and competing alternatives, (2) the formation of preference profiles and collective choices, and (3) the negotiation among agents as conflicts arise in group decision making. In this paper, we focus on the computational mechanisms developed to support steps (2) and (3) of the scheme. In addition, the practicality of the scheme is illustrated with examples taken from a working prototype dealing with collaborative structural design of buildings.
Understanding the differences between VDM and Z
Authors: I. J. Hayes, C. B. Jones, J. E. Nicholls
Venue: ACM SIGSOFT Software Engineering Notes (1994)

This paper attempts to provide an understanding of the interesting differences between two well-known specification languages.
Teaching Your System to Share
Authors: Ken Pimentel, Brian Blau
Venue: IEEE Computer Graphics and Applications (1994)

Abstract: Creating multi-user virtual worlds is a relatively new challenge for developers of virtual reality applications. It is especially challenging to build networked VR systems based on inexpensive PC-based hardware, due to limitations in system software and inefficient networking hardware. This article explains how we created a multi-person shared virtual environment using DOS-based PCs. It also covers some of the design goals in creating a collaborative design tool for creating and modifying virtual buildings. Workroom is a general purpose simulation infrastructure that allows multiple participants to interact in unpredictable ways while minimizing simulation latency.
The parallel solution of nonsymmetric sparse linear systems using the H* reordering and an associated factorization
Authors: K. A. Gallivan, B. A. Marsolf, H. A. G. Wijshoff
Venue: Proceedings of the 8th international conference on Supercomputing (1994)

In this paper, a nonsymmetric sparse linear system solver based on the exploitation of multilevel parallelism is proposed. One of the main issues addressed is the application of tearing techniques to enhance large grain parallelism in a manner that maintains reasonable stability. This is accomplished by a combination of a novel reordering technique (H*) and pivoting strategy. The large grain parallelism exposed by the reordering is combined with medium (various parallel row updates strategies) and fine grain (vectorization) parallelism to allow adaptation to a wide range of multiprocessor architectures. Experimental results are presented which show the effectiveness of the reordering, as well as the stability and efficiency of the solver.
Error in Unix commands dc and bc for multiple-precision-arithmetic
Authors: Ingo Dittmer
Venue: ACM SIGNUM Newsletter (1993)

Erroroneous computations were found in the modulo-function % of the multiple-precision-software dc, standard in Unix trade; -systems. Since the command bc is based upon dc, it is concerned, too.
Handling audio and video streams in a distributed environment
Authors: Alan Jones, Andrew Hopper
Venue: Proceedings of the fourteenth ACM symposium on Operating systems principles (1994)

Handling audio and video in a digital environment requires timely delivery of data. This paper describes the principles adopted in the design of the Pandora networked multi-media system. They attempt to give the user the best possible service while dealing with error and overload conditions.Pandora uses a sub-system to handle the multi-media peripherals. It uses transputers and associated Occam code to implement the time critical functions. Stream implementation is based on self-contained segments of data containing information for delivery, synchronisation and error recovery. Decoupling buffers are used to allow concurrent operation of multiple processing elements. Clawback buffers are used to resynchronise streams at their destinations with minimum latency.The system has proved robust in normal use, under overload, and in the presence of errors. It has been in use for a number of years.The principles involved in this design are now being used in the development of two complementary systems. One approach explodes Pandora by having the camera, microphone, speaker and display as independent units linked only by the LAN. The other approach integrates these devices as peripheral cards in a powerful workstation.
The Information Bus: an architecture for extensible distributed systems
Authors: Brian Oki, Manfred Pfluegl, Alex Siegel, Dale Skeen
Venue: Proceedings of the fourteenth ACM symposium on Operating systems principles (1994)

Research can rarely be performed on large-scale, distributed systems at the level of thousands of workstations. In this paper, we describe the motivating constraints, design principles, and architecture for an extensible, distributed system operating in such an environment. The constraints include continuous operation, dynamic system evolution, and integration with extant systems. The Information Bus, our solution, is a novel synthesis of four design principles: core communication protocols have minimal semantics, objects are self-describing, types can be dynamically defined, and communication is anonymous. The current implementation provides both flexibility and high performance, and has been proven in several commercial environments, including integrated circuit fabrication plants and brokerage/trading floors.
Original Contribution: Application of neural networks to fuzzy control
Authors: Faouzi Bouslama, Akira Ichikawa
Venue: Neural Networks (1993)

This paper gives a possible application of neural networks to fuzzy control. In fuzzy control a set of linguistic rules are given and by specifying a method of fuzzy reasoning and defuzzification an input-output relation is obtained. Fuzzy controllers thus obtained are usually irregular, and are not necessarily what experts expect. It is sometimes difficult to implement such controllers when processing time is limited. Here we attempt to dissolve such drawbacks using neural networks that can learn these input-output maps. We show that good neuro-controller can be obtained for an inverted pendulum system. The structure of the neuro-controller is simple, and hence analysis and implementation are easy. We discuss the stability of the system and confirm our results by experiments.