ppxscal/embedding_network huggingface dataset:
THE PARTIAL REHABILITATION OF PROPOSITIONAL RESOLUTION
Authors: Allen VanGelder, Fumiaki Kamiya
Venue:  (1996)

Resolution has not been an effective tool for deciding satisfiability of propositional CNF formulas, due to explosion of the search space, particularly when the formula is satisfiable. A new pruning method is described, which is designed to eliminate certain refutation attempts that cannot succeed. The method exploits the concept of ``autarky'''', which was introduced by Monien and Speckenmeyer. New forms of lemma creation are also introduced, which eliminate the need to carry out refutation attempts that must succeed. The resulting algorithm, called ``Modoc'''', is a modification of propositional model elimination. Informally, an autarky is a ``self-sufficient'''' model for some clauses, but which does not affect the remaining clauses of the formula. Whereas Monien and Speckenmeyer''s work was oriented toward finding a model, our method has as its primary goal to find a refutation in the style of model elimination. However, Modoc finds a model if it fails to find a refutation, essentially by combining autarkies. Unlike the pruning strategies of most refinements of resolution, autarky-related pruning only prunes refutation attempts that ultimately will be unsuccessful; consequently, it will not force the underlying search to find an unnecessarily long refutation. The other major innovation is Modoc''s lemma management. Building upon the C-literal strategy proposed by Shostak and studied further by Letz, Mayr and Goller, methods for ``eager'''' lemmas, ``quasi-persistent'''' lemmas, and two forms of controlled cut are described. Experimental data based on an implementation in C is reported. On random formulas, Modoc is not as effective as recently reported model-searching methods. On more structured formulas, such as circuit-fault detection, it is superior.
EXACT ARITHMETIC IN Q-BAR WITH APPLICATIONS IN CELESTIAL MECHANICS (Ph.D. Thesis)
Authors: Al Conrad
Venue:  (1995)

Consider a three-body system, such as an asteroid moving along a path dictated by Jupiter and the Sun. We summarize the dynamics of this system in a single matrix which is symplectic. We have written software which automates the tedious process of calculating the normal form of a symplectic matrix. Using this software, we have computed normal forms for hundreds of symplectic matrices. Using these examples, we have compiled a table of particularly nice Hamiltonian systems, uncovered which of these systems are conjugate, corrected an error in the published algorithm, formulated a new conjecture, and computed normal forms for several three-body systems which occur in nature. The symplectic normal form algorithm (first published by Burgoyne and Cushman in 1973) requires exact arithmetic. When coded in software, the algorithm must, for example, calculate (sqrt(2)*sqrt(2) - 1) - 1 as the integer zero. Using traditional software, the above expression evaluates to something closer to 11/25,000,000,000,000,000. We overcame this hurdle by applying results from field theory. In particular, we use the relationship between Q-bar and polynomial quotient space. Although we developed this system to solve the symplectic normal form problem, it can be applied to many problems which require exact arithmetic.
A Homotopy Algorithm for the Combined H2/H∞ Model Reduction Problem
Authors: Yuzhen Ge, Emmanuel G. Collins, Layne T. Watson, Dennis S. Bernstein
Venue:  (1992)

The problem of finding a reduced order model, optimal in the H2 sense, to a given system model is a fundamental one in control system analysis and design. The addition of an H∞ constraint to the H2 optimal model reduction problem results in a more practical yet computationally more difficult problem. Without the global convergence of probability-one homotopy methods the combined H2 /H∞ model reduction problem is difficult to solve. Several approaches based on homotopy methods have been proposed. The issues are the number of degrees of freedom, the well posedness of the finite dimensional optimization problem, and the numerical robustness of the resulting homotopy algorithm. Homotopy algorithms based on two formulations---input normal form; Ly, Bryson, and Cannon''s 2x2 block parametrization are developed and compared.
Multivision: A Game of Arbitrarily Long Play
Authors: A. S. Fraenkel
Venue:  (1997)

We define and analyze a game such that play from any position, except the last few, can be made arbitrarily long.
TOPOLOGICAL CONSIDERATIONS IN ISOSURFACE GENERATION
Authors: Jane Wilhelms, Allen VanGelder
Venue:  (1990)

An emerging technique for rendition of isosurfaces in sampled data is to consider cells with sample points as corners and approximate the isosurface in each cell by one or more polygons whose vertices are obtained by interpolation of the sample data. That is, each polygon vertex is a point on a cell edge, between two adjacent sample points, where the function is estimated to equal the desired threshold value. The two sample points have values on opposite sides of the threshold, and the interpolated point is called an *intersection point*. When one cell face has an intersection point in each of its four edges, then the correct connection among intersection points becomes ambiguous. An incorrect connection can lead to erroneous topology in the rendered surface, and possible discontinuities. We show that disambiguation methods, to be at all accurate, need to consider sample values in the neighborhood outside the cell. This paper studies the problems of disambiguation, reports on some solutions, and presents some statistics on the occurrence of such ambiguities. A natural way to incorporate neighborhood information is through the use of calculated gradients at cell corners. These quantities are needed for other purposes, and they provide insight into the behavior of a function in well-understood ways. We introduce two *gradient-consistency heuristics* that use calculated gradients at the corners of ambiguous faces, together with the function values at those corners, to disambiguate at a reasonable computational cost. These methods give the correct topology on several examples that caused problems for other methods we examined.
Lower Bounds on Communication Loads and Optimal Placements in Torus Networks
Authors: M. C Azizoglu, Omer Egecioglu
Venue:  (1998)

Fully-populated torus-connected networks, where every node has a processor attached, do not scale well since load on edges increases superlinearly with network size under heavy communication, resulting in a degradation in network throughput. In a partially-populated network, processors occupy a subset of available nodes, and a routing algorithm is specified among the processors placed. Analogous to multistage networks, it is desirable to have the total number of messages being routed through a particular edge increase at most linearly with the size of the placement on torus networks. Recently, Blaum, Bruck, Pifarre, and Sanz investigated placements and provided both a lower bound, and optimal placements in the cases of 2 and 3-dimensional $k$-tori, consisting of $k$ and $k^2$ processors, respectively. In this technical report we show formally that to achieve linear load in a $d$-dimensional $k$-torus, the number of processors in the placement must be $O(k^{d-1})$. We use this to construct a tighter lower bound for the maximum load of a placement for 4 or more dimensions. Based on these results, we give optimal placements and their corresponding routing algorithms in tori with arbitrary number of dimensions.
Computational Experience with Approximation Algorithms for the Set Covering Problem
Authors: T. Grossman, A. Wool
Venue:  (1994)

The Set Covering Problem (SCP) is a well known combinatorial optimization problem, which is NP-hard. We conducted a comparative study of eight different approximation algorithms for the SCP, including several greedy variants, fractional relaxations, randomized algorithms and a neural network algorithm. The algorithms were tested on a set of random-generated problems with up to 500 rows and 5000 columns, and on two sets of problems originating in combinatorial questions with up to 28160 rows and 11264 columns. On the random problems and on one set of combinatorial problems, the best algorithm among those we tested was the neural network algorithm, with greedy variants very close in second and third place. On the other set of combinatorial problems, the best algorithm was a greedy variant and the neural network performed quite poorly. The other algorithms we tested were always inferior to the ones mentioned above.
Rule Interpreters in ELEKTRA
Authors: I. D. Craig
Venue:  (1991)

In this paper, we describe a number of rule interpreters, each of which is presented in production rule form. Each of the interpreters can be executed as an ordinary ELEKTRA ruleset which interprets all or some of the rules in an ELEKTRA system. The interpreters, therefore, override the default behaviour of the ELEKTRA interpreter. Some of the interpreters that we describe are capable of interpreting themselves: others can be combined into larger, reflective interpreters. The aim of the paper is not, however, to show how sophisticated reflective processing can be achieved in ELEKTRA, but, rather, to show that ELEKTRA is powerful enough to support a wide variety of different interpreters without requiring any changes to its code. None of the interpreters requires additional system code in order to work: ELEKTRA provides all of the facilities used by the rulesets as part of its standard library. This paper is offered as additional evidence of the enormous power of the ELEKTRA system.
Design Strategies for Algebraic Specifications
Authors: Sergio Antoy
Venue:  (1989)

The algebraic specification of abstract data types can be affected by serious flaws. Rather than attempting, as it is usually done, to detect defects in a specification a posteriori, i.e., after the specification has been designed, we propose two strategies for addressing this problem a priori, i.e., during design phase of a specification. We investigate two common flaws of algebraic operations, under- and over-specification, determine sufficient and/or necessary conditions to avoid them, and show how to obtain these conditions in a constructive way. Our approach is based on the completeness and parsimony properties of sets of tuples and on a recursive mechanism which extends primitive recursion from natural numbers to abstract data types. Finally, we attempt to assess the power and the limitations of our approach and relate the properties on which it is based to other similar properties which have appeared in the literature. We formally prove a number of results and illustrate their application to the design of specifications by means of examples.
MPI Process Swapping: Architecture and Experimental Verification
Authors: Otto Sievert, Henri Casanova
Venue:  (2003)

Parallel computing is now popular and mainstream, but performance and ease-of-use remain elusive to many end-users. There exists a need for performance improvements that can be easily retrofitted to existing parallel applications. In this paper we present MPI process swapping, a simple performance enhancing add-on to the MPI programming paradigm. MPI process swapping improves performance by dynamically choosing the best available resources throughout application execution, using MPI process over-allocation and real-time performance measurement. Swapping provides fully automated performance monitoring and process management, and a rich set of primitives to control execution behavior manually or through an external tool. Swapping, as defined in this implementation, can be added to iterative MPI applications and requires as few as three lines of source code change. We verify our design for a particle dynamics application in a commercial production computing environment.
The Load, Capacity and Availability of Quorum Systems
Authors: M. Naor, A. Wool
Venue:  (1995)

A quorum system is a collection of sets (quorums) every two of which intersect. Quorum systems have been used for many applications in the area of distributed systems, including mutual exclusion, data replication and dissemination of information. Given a strategy to pick quorums, the load L(S) is the minimal access probability of the busiest element, minimizing over the strategies. The capacity Cap(S) is the highest quorum access rate that S can handle. We show that for any quorum system, Cap(S) = 1/L(S). The availability of a quorum system S is the probability that at least one quorum survives, assuming that each element fails independently with probability p. A tradeoff between L(S) and the availability of S is shown. None of the existing constructions of quorum systems achieves simultaneously good availability and low load. We present four novel constructions of quorum systems, all featuring optimal or near optimal load, and high availability. The best construction, based on paths in a grid, has a load of O(1/On), and a failure probability of exp(-L(On)) when the elements fail with probability p > 1/>sub<2>/sub<. Moreover, even in the presence of faults, with exponentially high probability the load of this system is still O(1/On). The analysis of this scheme is based on Percolation Theory.
Refinement of TF-IDF schemes for web pages using their hyperlinked neighboring pages
Authors: Kazunari Sugiyama, Kenji Hatano, Masatoshi Yoshikawa, Shunsuke Uemura
Venue: Proceedings of the fourteenth ACM conference on Hypertext and hypermedia (2003)

In IR (information retrieval) systems based on the vector space model, the TF-IDF scheme is widely used to characterize documents. However, in the case of documents with hyperlink structures such as Web pages, it is necessary to develop a technique for representing the contents of Web pages more accurately by exploiting the contents of their hyperlinked neighboring pages. In this paper, we first propose several approaches to refining the TF-IDF scheme for a target Web page by using the contents of its hyperlinked neighboring pages, and then compare the retrieval accuracy of our proposed approaches. Experimental results show that, generally, more accurate feature vectors of a target Web page can be generated in the case of utilizing the contents of its hyperlinked neighboring pages at levels up to second in the backward direction from the target page.
More on Counting Sequences
Authors: V. Bronstein, A. S. Fraenkel
Venue:  (1995)

This note can be viewed as a logical continuation of our previous Note published earlier in the Monthly. We shall repeat here, briefly, its main results to make the reading easier. A counting sequence S is a sequence of sequences {Si}Yi = 0 of positive integers. The sequence Si+1 is obtained from Si by counting the number mk of times an integer k occurs in Si and writing down in Si+1 the pairs mk,k in increasing order of the factors k, for all k for which mk < 0.
View Derivation Graph with Edge Fitting for Data Warehousing in Disconnected Environments
Authors: I. Stanoi, D. Agrawal, A. E Abbadi
Venue:  (1999)

Data warehouse views cache summarized information from queries over one or multiple distributed base sources. In this paper, we address the problem of data warehouse maintenance in an environment where base source data can be stored on mobile devices. The requirements of a partially disconnected world lead to significant tradeoffs between the view update cost on one hand, and the level of freshness of the view on the other hand. Current decentralized maintenance methods that can be applied to a disconnected environment involve either replicating of source data at the view, or computing view updates through queries to all base sources. Replication may involve excessive storage overhead, while view update may be blocked due to the disconnection of any of the base sources. We propose a view maintenance approach that stores path information corresponding to data traditionally stored at the view, and offers several important advantages. From the maintenance point of view, our method reduces local computation at the view as well as communication with the outside sources, and lowers the execution load on the base sources. From the user''s perspective, reducing the probability of executing view update queries at all base sources leads to a more up-to-date state of the data warehouse view.
Computing the largest inscribed isothetic rectangle
Authors: Helmut Alt, David Hsu, Jack Snoeyink
Venue:  (1994)

This paper describes an algorithm to compute, in Theta(log n) time, a rectangle that is contained in a convex n-gon, has sides parallel to the coordinate axes, and has maximum area. With a slight modification it will compute the smallest perimeter. The algorithm uses a tentative prune-and-search approach, even though this problem does not appear to fit into the functional framework of Kirkpatrick and Snoeyink.
Campus-Wide Computing: Early Results Using Legion at The University of Virginia
Authors: Andrew S. Grimshaw, Anh Nguyen-Tuong, William A. Wulf
Venue:  (1995)

The Legion project at the University of Virginia is an attempt to provide system services that provide the illusion of a single virtual machine to users, a virtual machine that provides both improved response time via parallel execution and greater throughput. Legion is targeted towards both workstation clusters and towards larger, wide-area, assemblies of workstations, supercomputers, and parallel supercomputers. Rather than construct Legion from scratch we are extending an existing object-oriented parallel processing system by aggressively incorporating lessons learned over twenty years by the heterogeneous distributed systems community. The campus-wide virtual computer is an early Legion prototype. In this paper we present challenges that had to be overcome to realize a working CWVC, as well as performance on a production biochemistry application.
A Review of Publishing and Access Issues for Optical Discs and CD-ROM''s
Authors: Edward A. Fox
Venue:  (1988)

Optical discs in general and CD-ROM in particular are helping fuel a revolution in information access that media, hardware, and information providers and producers hope will not only reach a variety of targeted groups, but will also lead to interactive involvement of the general public. This chapter reviews the events of recent years in this dynamic area; discusses the variety of read-only, write once, and erasable media that have been developed; considers standards that provide consumers with confidence to acquire. new systems and products; describes approaches and activities to publishing and accessing CD-ROM and related materials; surveys the broad application areas; considers the research underway and required; anticipates future trends; and draws conclusions regarding the importance of this exciting technology. While videodiscs are frequently referred to, the focus is on CD-ROM, along with related products like CD-I. The importance of having second generation products that are highly interactive and which draw on the best work on hypertext, hypermedia, and retrieval methods is emphasized.
A Parallel Transputer System with Fast Pipeline Interconnection
Authors: Bernhard Lang, Hans Burkhardt
Venue:  (1990)

Transputers are processors which are well suited for the parallel implementation of medium and high- level image processing algorithms. The serial data Links may well be used for data interchange within the image processing task. They form, however, a bottleneck with respect to loading and unloading of mass data with video data rates. During the last years a parallel Transputer system was developed and implemented at the University of Technology in Hamburg-Harburg. Besides the processing power the very important aspect of communi- cation power and topology was considered when designing the architecture of the system. As a result the system has three different communication structures: one for algorithms data exchange, one for loading and unloading of mass data like images and one for the system communication of the distributed operating software. After an introduction and some architectural assumptions this paper introduces this system including its communication structures and presents the implementation of a fast algorithm for the estimation of motion parameters in image sequences.
J-Inner Matrix Functions, Interpolation and Inverse Problems for Canonical Systems, II: The Inverse Monodromy Problem
Authors: D. Z. Arov, H. Dym
Venue:  (1999)

This is the second of a planned sequence of papers on inverse problems for canonical systems of differential equations. It is devoted to the inverse monodromy problem for canonical integral and differential systems. In this part, which focuses on the case of a diagonal signature matrix J, a parametrization is obtained of the set of all solutions M(t) for the inverse problem for integral systems in terms of two chains of entire matrix valued inner functions. Special classes of solutions correspond to special choices of these chains. This theme will be elaborated upon further in a third part of this paper which will be published in a subsequent issue of this journal. There the emphasis will be on symmetries and growth conditions all of which serve to specify or restrict the chains alluded to above, from the outside, so to speak.
Constraint Nets: A Semantic Model for Real-Time Embedded Systems
Authors: Ying Zhang, Alan K. Mackworth
Venue:  (1992)

We take a real-time embedded system to be the control system of a plant in an open environment, where the control is realized by computation in digital or analog form. The key characteristic of a real-time embedded system is that computation is interleaved or in parallel with actions of the plant and events in the environment. Various models for real-time embedded systems have been proposed in recent years, most of which are extensions of existing concurrency models with delays or time bounds on transitions. In this paper, we present a different approach to modeling real-time systems. We take the overall system as a dynamic system, in which time or event structures are considered as an intrinsic dimension. Our model, called the Constraint Net model (CN), is capable of expressing dynamic behaviors in real-time embedded systems. It captures the most general structure of dynamic systems so that systems with discrete as well as dense time and asynchronous as well as synchronous event structures can be modeled in a unified framework. It models the dynamics of the environment as well as the dynamics of the plant and the dynamics of the computation and control. It provides multiple levels of abstraction so that a system can be modeled and developed hierarchically. By explicitly representing locality, CN can be used to explore true concurrency in distributed systems. With its rigorous formalization, CN provides a programming semantics for the design of real-time embedded systems. It also serves as a foundation for specification, verification, analysis and simulation of the complete dynamic system.