ppxscal/embedding_network huggingface dataset:
Leopoldt's conjecture for imaginary Galois number fields
Authors: Norbert Klingen
Venue: Journal of Symbolic Computation (1990)

In studying Leopoldt's conjecture for Galois number fields a sufficient condition is proposed which includes the known criteria and moreover refers only to the character table of the Galois group in question. Hence it may easily be checked. Tables of the computations are given. New examples, if only few, of imaginary number fields are exhibited for which Leopoldt's conjecture is proved to be true for all primes p. Some of them are covered by some kind of ''Verschiebungssatz'' for Leopoldt's conjecture.
Principal signatures for higher-order program modules
Authors: Mads Tofte
Venue: Proceedings of the 19th ACM SIGPLAN-SIGACT symposium on Principles of programming languages (1992)

Under the Damas-Milner type discipline for functional languages, every expression has principal type, if it elaborates at all. In the type discipline for ML Modules, a signature expression has a principal signature, if it elaborates at all. However, while functions can be higher-order in ML, parameterised modules in ML are first-order only. We present a type discipline for a skeletal higher-order module language which has principal signatures. Sharing and multiple views of structures are handled in a manner which is compatible with the semantics of the first-order ML modules.
New algorithms for minimum area k-gons
Authors: David Eppstein
Venue: Proceedings of the third annual ACM-SIAM symposium on Discrete algorithms (1992)

Given a set P of n points in the plane, we wish to find a set Q &sub; P of k points for which the convex hull conv(Q> has the minimum area. We solve this, and the related problem of finding a minimum area convex k-gon, in time O(n2 log n) for fixed k, almost matching known bounds for the minimum area triangle problem. Our algorithm is based on finding a certain number of nearest vertical neighbors to each line segment determined by two input points. We use a classical result of Ramsey theory to prove that these nearest neighbors suffice to determine the minimum convex k-gon.
Autoepistemic logic
Authors: Wiktor Marek, Mirosław Truszczyński
Venue: Journal of the ACM (JACM) (1991)

Autoepistemic logic is one of the principal modes of nonmonotonic reasoning. It unifies several other modes of nonmonotonic reasoning and has important application in logic programming. In the paper, a theory of autoepistemic logic is developed. This paper starts with a brief survey of some of the previously known results. Then, the nature of nonmonotonicity is studied by investigating how membership of autoepistemic statements in autoepistemic theories depends on the underlying objective theory. A notion similar to set-theoretic forcing is introduced. Expansions of autoepistemic theories are also investigated. Expansions serve as sets of consequences of an autoepistemic theory and they can also be used to define semantics for logic programs with negation. Theories that have expansions are characterized, and a normal form that allows the description of all expansions of a theory is introduced. Our results imply algorithms to determine whether a theory has a unique expansion. Sufficient conditions (stratification) that imply existence of a unique expansion are discussed. The definition of stratified theories is extended and (under some additional assumptions) efficient algorithms for testing whether a theory is stratified are proposed. The theorem characterizing expansions is applied to two classes of theories, K1-theories and ae-programs. In each case, simple hypergraph characterization of expansions of theories from each of these classes is given. Finally, connections with stable model semantics for logic programs with negation is discussed. In particular, it is proven that the problem of existence of stable models is NP-complete. &mdash;Authors' Abstract
The Expected (Not Worst-Case) Throughput of the Ethernet Protocol
Authors: Dug-Kyoo Choi, B. G. Kim
Venue: IEEE Transactions on Computers (1991)

The Ethernet protocol is analyzed using a space-time model in which the occurrence of a collision is determined not only by frame arrival times but also by locations of nodes. The space-time model is described, and the expected throughput of the Ethernet protocol is derived assuming that frames arrive by a Poisson process. Numerical results show that the expected throughput can be significantly higher than earlier time-domain results when the spatial dimension a
Steps Toward Architecture-Independent Image Processing
Authors: Jon A. Webb
Venue: Computer (1992)

Adapt, an architecture-independent language based on the split-and-merge model, is presented. It is specialized for efficient, parallel computation of image-processing algorithms. The split-and-merge programming model is first examined. The Adapt language and its implementation are then described, and its performance is considered.
A course for the nonmajor: teaching collaborative problem solving via the classical computer science space-time tradeoff
Authors: Stewart A. Denenberg
Venue: Proceedings of the 1990 ACM annual conference on Cooperation (1990)

Too often the department of Computer Science's service course is limited to either the major course itself or some course about computer science. While the former is usually much too demanding for nonmajors, the latter never fully allows the student to design, debug and actually run the solution to a complex problem on a computer. We propose a course which includes the use of a friendly but nontrivial programming language (Logo) coupled to a problem set which demonstrates the efficacy of top-down design as a problem solving technique. The paper describes a four-part curriculum unit based on an &ldquo;Alphabet&rdquo; programming project. In this Alphabet Project, student groups design and implement an alphabet of letters that are to be drawn on the screen via Turtle Graphics in Logo. The end result of the project is to make the Turtle trace out variable-sized letters on the screen as the associated keys on the keyboard are pressed. While the instructor supplies the driver program, the students work together to determine a reasonable set of &ldquo;core shapes&rdquo; which can be used to assemble each letter of the alphabet. Throughout the four parts of the project design is constrained by assigning &ldquo;costs&rdquo; to the memory space and execution time associated with the procedures which draw the core shapes and the letters. Some lively discussions develop around the ideas of primitives and parsimony that are surprisingly similar to those in an upper-level computer science class in programming language design.
Using Models to Improve Stereo Reconstruction
Authors: Henri Maître, Wei Luo
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1992)

The authors propose the combination of photometric and stereometric information to solve the stereo vision problem in the case of a man-made environment. A method to introduce geometrical models in the stereo process in order to improve the accuracy of the depth measurement and to extend the depth map to points where no measurements have been made is presented. This method is based on a parameterization of the object surfaces and relies on a systematic comparison of the result of a stereo process with the photometric (or gray-level) image. The proposed approach improves the accuracy of the stereo information and its density by introducing a hypothesis on the object surfaces. Two kinds of hypothesis are developed: planar and quadratic objects. Reconstructions of complex scenes are given.
Optimal Prioritized Conflict Resolution on a Multiple Access Channel
Authors: Charles U. Martel, Wen-Hsien L. Melody Moh
Venue: IEEE Transactions on Computers (1991)

A multiple access broadcast network (MABN) is a computer network in which there is a single shared communication channel and every network node can receive all messages transmitted over the channel. A major difficulty in using broadcast communication is the issue of access to the channel. The authors deal with the following prioritized conflict resolution problem: a collection of c messages is initially distributed among nodes on an MABN; each message is associated with a value representing its priority or deadline; and it is required that the messages be broadcast in ascending order of this value. This problem is solved by a distributed prioritized conflict resolution algorithm. It is proved that the expected waiting time of the ith network node to transmit is Theta (i+log c), which is optimal. It is also shown that the algorithm runs in the expected linear time, which is optimal in both the number of slots used and the total elapsed time including local processing.
The desk area network
Authors: Mark Hayter, Derek McAuley
Venue: ACM SIGOPS Operating Systems Review (1991)

A novel architecture for use within an end computing system is described. This attempts to extend the concepts used in modern high speed networks into computer system design. A multimedia workstation is being built based on this concept to evaluate the approach.
An optimal convex hull algorithm and new results on cuttings (extended abstract)
Authors: Bernard Chazelle
Venue: Proceedings of the 32nd annual symposium on Foundations of computer science (1991)

An optimal algorithm for computing hyperplane cuttings is given. It results in a new kind of cutting, which enjoys all the properties of the previous ones and, in addition, can be refined by composition. An optimal algorithm for computing the convex hull of a finite point set in any fixed dimension is also given.
Using Horizontal Prefetching to Circumvent the Jump Problem
Authors: Daniel C. McCrackin, Barna Szabados
Venue: IEEE Transactions on Computers (1991)

The principle of a novel prefetching mechanism, horizontal demand prefetching, is presented. The mechanism allows deep prefetching without jump related misses by prefetching horizontally across independent instruction streams. The scheme can achieve high memory utilization at the expense of processor utilization. The mechanism permits very rapid context switching with no overhead for a hardware-limited number of tasks. The design and performance of a 16-b prototype machine is presented. The prototype exhibits a nonlinear relationship between the number of running streams and processor performance. This saturating performance-tasks relationship suggests that operations like process synchronization and interprocessor communication could be implemented very efficiently. Stalled streams need not greatly affect processor throughput.
Programming with Streams in a Pascal-Like Language
Authors: Ikuo Nakata, Masataka Sassa
Venue: IEEE Transactions on Software Engineering (1991)

A description is given of features which were added to a conventional programming language that will manipulate streams of values. A stream is a sequence of values of a certain fixed type. The number of elements of a stream may be determined at execution time, and evaluation of each element can be postponed until its value is actually needed. Many programs can be expressed naturally and clearly as networks of processes communicating by means of streams. The network is called a composite function and consists of several component functions. Since component functions are connected solely by streams, they greatly increase the flexibility of combinations and the reusability of programs. Loop statements can be considered as iterative statements over streams. One general problem in these networks is the mechanism of terminating each process of the network. A practical solution for this problem is presented. Comparisons to other programming styles, such as coroutines, Lisp, functional programming, and dataflow languages, are described. Three modes of execution are considered for the implementation of composite functions: parallel mode, coroutine mode, and inline mode. In the inline mode, a composite function is expanded and transformed into a single function, realizing maximum run-time efficiency. Algorithms for this expansion are given.
Minimal covers revisited: correct and efficient algorithms
Authors: Jim Diederich
Venue: ACM SIGMOD Record (1991)

In [1] Nummenmaa and Tanisch show that the algorithm in [2] for computing minimal covers is incorrect even though it purports to correct the algorithms in [3-6]. As they illustrate with F = { A B &rarr; C}, the algorithm in [2] allows B to be eliminated as an extraneous attribute since the dependency AB &rarr; C is implied by A &rarr; C using augmentation. Thus F is replaced by F&prime; = [A &rarr; C], which is clearly not equivalent to F. The problematic step of the algorithm in [2] that allows this to occur is Consider each dependency X &rarr; A in some order. If Z is a subset of X such that F is contained in the closure of (F - {X &rarr; A}) &cup; {Z &rarr; A], then immediately replace X &rarr; A by Z &rarr; A in F. This step continues until no left side of any dependency in F can be reduced
Inheritance and constraint-based grammar formalisms
Authors: Rémi Zajac
Venue: Computational Linguistics (1992)

We describe an approach to unification grammars that integrates two paradigms: the object-oriented approach, which offers multiple inheritance, complex objects with role-value restrictions and role-values equality, querying as subsumption; the relational programming approach, which offers declarativity, logical variables, nondeterminism with backtracking, and existential queries. This approach is embodied in a constraint-based object-oriented formalism. The interpreter of the formalism is described as a term rewriting system based on unification of typed feature structures.The grammar writer organizes unification grammars as inheritance networks of typed feature structures. Complex linguistic structures are described by means of recursive type constraints. We illustrate the use of inheritance networks with two examples: an HPSG example where implication (as used for "principles") is modeled using inheritance and an example of bilingual transfer where the minimal amount of information needed for the translation is specified at different levels of generalization.
Futurebus+ as an I/O bus: profile B
Authors: Barbara P. Aichinger
Venue: ACM SIGARCH Computer Architecture News (1992)

The IEEE Futurebus+ is a very fast (3GB/sec.), industry standard backplane bus specification for computer systems. Futurebus+ was designed independent of any CPU architecture so it is truly open. With this open architecture Futurebus+ can be applied to many different computing applications. Profile B is a subset of the IEEE 896 Futurebus+ standard and targets high performance, general purpose computer I/O applications. This paper describes how and why the functional, electrical, mechanical and environmental characteristics were chosen.
Object-oriented database for intelligent engineering applications (abstract)
Authors: Marguerite Summers, John D. McGregor
Venue: Proceedings of the 1990 ACM annual conference on Cooperation (1990)

Intelligent engineering systems are often developed utilizing the object-oriented paradigm. These applications of the object-oriented paradigm require the persistent storage of instance objects. One solution to this storage problem is the development of object-oriented databases. The development of large software systems requires the coordination of many of different types of documents. Specifications, designs, documentation, and code segments must all be available for retrieval by multiple users. Many versions of each code segment may be maintained. The development environment should handle all the data on the system under development in a uniform manner. Code, design diagrams, and screen images should all be available through a uniform interface. The flexibility of the object-oriented database permits the construction of data types to represent these diverse kinds of information The intelligent system can interact with the database to assemble versions of a software system for a given hardware configuration or for varying capacities of the underlying data structures. The intelligent environment would generate queries against a database of complex and varying objects. Object-oriented database technology has several implications for intelligent engineering applications: Management of Complexity - The object-oriented paradigm packages complexity and relieves the outside world of details of its structure and functionality. Accurate Modeling - The rich variety of data representations possible in the object-oriented environment provides the modeler with sufficient power to model complex data structures and their associated functionality. Data Integrity - Many engineering applications have been too complex to allow for database support. The object-oriented paradigm encapsulates all of the data for one event into one integral representation
Constant-Factor Redundant CORDIC for Angle Calculation and Rotation
Authors: Jeong-A. Lee, Tomás Lang
Venue: IEEE Transactions on Computers (1992)

A constant-factor redundant-CORDIC (CFR-CORDIC) scheme, where the scale factor is kept constant while an angle for plane rotations is computed, is developed. The direction of rotation is determined from an estimate of the sign, and convergence is assured by suitably placed correcting iterations. The number of iterations in the CORDIC rotation unit is reduced by about 25% by expressing the direction of the rotation in radix-2 and radix-4, and conversion to conventional representation is done on the fly. The performance of CFR-CORDIC is estimated and compared with that of previously proposed schemes. It is found to provide an execution time similar to that of redundant CORDIC with a variable scaling factor, with a significant saving in area.
Structure and semantics in OODB class specifications
Authors: J. Geller, Y. Perl, E. J. Neuhold
Venue: ACM SIGMOD Record (1991)

A class specification contains both structural aspects and semantic aspects. We introduce a mathematically based distinction between structural and semantic aspects. We show how this distinction is used to identify all structural aspects of a class specification to be included in the object type of a class. The model obtained is called the Dual Model due to the separation of structure and semantics in the class specification. Advantages of the separation of structure and semantics have been discussed in previous papers and include separate hierarchies for structural and semantic aspects, refined inheritance mechanisms, support of physical database design and structural integration which is impossible in other models.
Prism-Methodology and Process-Oriented Environment
Authors: Nazim H. Madhavji, Wilhelm Schäfer
Venue: IEEE Transactions on Software Engineering (1991)

The Prism model of engineering processes and an architecture which captures this model in its various components are described. The architecture has been designed to hold a product software process description the life-cycle of which is supported by an explicit representation of a higher-level (or meta) process description. The central part of this paper describes the nine-step Prism methodology for building and tailoring process models and gives several scenarios to support this description. In Prism, process models are built using a hybrid process modeling language that is based on a high-level Petri net formalism and rules. An important observation is that this environment should be seen as an infrastructure for carrying out the more difficult task of creating sound process modelsn.
The Stanford Dash Multiprocessor
Authors: Daniel Lenoski, James Laudon, Kourosh Gharachorloo, Wolf-Dietrich Weber, Anoop Gupta, John Hennessy, Mark Horowitz, Monica S. Lam
Venue: Computer (1992)

The overall goals and major features of the directory architecture for shared memory (Dash) are presented. The fundamental premise behind the architecture is that it is possible to build a scalable high-performance machine with a single address space and coherent caches. The Dash architecture is scalable in that it achieves linear or near-linear performance growth as the number of processors increases from a few to a few thousand. This performance results from distributing the memory among processing nodes and using a network with scalable bandwidth to connect the nodes. The architecture allows shared data to be cached, significantly reducing the latency of memory accesses and yielding higher processor utilization and higher overall performance. A distributed directory-based protocol that provides cache coherence without compromising scalability is discussed in detail. The Dash prototype machine and the corresponding software support are described.
A new framework for separating user interfaces from application programs
Authors: Hisashi Nakatsuyama, Makoto Murata, Koji Kusumoto
Venue: ACM SIGCHI Bulletin (1991)

We propose an object-oriented user interface framework that allows 1) easy development of user interfaces, 2) separation of user interfaces from application programs, and 3) simultaneous and coordinated usage of several user interfaces of one program. Daemons keep these user interfaces consistent with the status of the program, while hiding the user interfaces from the program. Mapping objects, which are parts of user interfaces, are introduced to map complicated status of application programs to visual presentation. Consistency among subwindows of one window is also kept by daemons of the window. Again, each subwindow is hidden from the other subwindows.
On computational aspects of bounded linear least squares problems
Authors: Achiya Dax
Venue: ACM Transactions on Mathematical Software (TOMS) (1991)

The paper describes numerical experiments with active set methods for solving bounded linear least squares problems. It concentrates on two problems that arise in the implementation of the active set method. One problem is the choice of a good starting point. The second problem is how to move out of a &ldquo;dead point.&rdquo; The paper investigates the use of simple iterative methods to solve these problems. The results of our experiments indicate that the use of Gauss-Seidel iterations to obtain a starting point is likely to provide large gains in efficiency. Another interesting conclusion is that dropping one constraint at a time is advantageous to dropping several constraints at a time.
Improving the Reliability of Function Point Measurement: An Empirical Study
Authors: Chris F. Kemerer, Benjamin S. Porter
Venue: IEEE Transactions on Software Engineering (1992)

One measure of the size and complexity of information systems that is growing in acceptance and adoption is function points, a user-oriented, nonsource line of code metric of the systems development product. Previous research has documented the degree of reliability of function points as a metric. This research extends that work by (a) identifying the major sources of variation through a survey of current practice, and (b) estimating the magnitude of the effect of these sources of variation using detailed case study data from commercial systems. The results of this research show that a relatively small number of factors has the greatest potential for affecting reliability, and recommendations are made for using these results to improve the reliability of function point counting in organizations.
Theory and Design of t-Error Correcting, k-Error Detecting and d-Unidirectional Error Detecting Codes with d<k<t
Authors: Dimitris Nikolos, Alexandros Krokos
Venue: IEEE Transactions on Computers (1992)

The fundamental theory of t-error correcting, k-error detecting, and d-unidirectional error detecting codes with d