ppxscal/embedding_network huggingface dataset:
Social translucence: an approach to designing systems that support social processes
Authors: Thomas Erickson
Venue: ACM Transactions on Computer-Human Interaction (TOCHI) (2000)

We are interested in desiging systems that support communication and collaboration among large groups of people over computing networks. We begin by asking what properties of the physical world support graceful human-human communication in face-to-face situations, and argue that it is possible to design digital systems that support coherent behavior by making participants and their activites visible to one another. We call such systems &ldquo;socially translucent systems&rdquo; and suggest that they have three characteristics&mdash;visbility, awareness, and accountability&mdash;which enable people to draw upon their experience and expertise to structure their interactions with one another. To motivate and focus our ideas we develop a vision of knowledge communities, conversationally based systems that support the creation, management and reuse of knowledge in a social context. We describe our experience in designing and deploying one layer of functionality for knowledge communities, embodied in a working system called &ldquo;Barbie&rdquo; and discuss research issues raised by a socially translucent approach to design.
Maximum Principle for a Hybrid System Via Singular Perturbations
Authors: G. Grammel
Venue: SIAM Journal on Control and Optimization (1999)

We prove a maximum principle of Pontryagin type for the time optimal control of a hybrid system. The system is nonlinear and consists of a controlled coupled ODE/PDE. The control input acts via the boundary and the interior of the domain. Systems of this type frequently arise in modeling population dynamics in a contaminated environment. For the regularization we use Ekeland's variational principle along with a singular perturbation technique. For this purpose we introduce a new trajectory on an additional exterior domain, whose size may be considered as a singular perturbation parameter. It turns out that the maximum principle is stable with respect to the size of the additional exterior domain. The technique allows us to obtain necessary optimality conditions without involving measure boundary data.
Combining periodic and probabilistic checkpointing in optimistic simulation
Authors: Francesco Quaglia
Venue: Proceedings of the thirteenth workshop on Parallel and distributed simulation (1999)

This paper presents a checkpointing scheme for optimistic simulation which is a mixed approach between periodic and probabilistic checkpointing. The latter, basing on statistical data collected during the simulation, aims at recording as checkpoints states of a logical process that have high probability to be restored due to rollback (this is done in order to make those states immediately available). The periodic part prevents performance degradation due to state reconstruction (coasting forward) cost whenever the collected statistics do not allow to identify states highly likely to be restored.Hence, this scheme can be seen as a highly general solution to tackle the checkpoint problem in optimistic simulation. A performance comparison with previous solutions is carried out through a simulation study of a store-and-forward communication network in a two-dimensional torus topology.
Evolution and evaluation of SPEC benchmarks
Authors: Jozo J. Dujmovic
Venue: ACM SIGMETRICS Performance Evaluation Review (1998)

We present a method for quantitative evaluation of SPEC benchmarks. The method is used for the analysis of three generations of SPEC component-level benchmarks: SPEC89, SPEC92, and SPEC95. Our approach is suitable for studying (1) the redundancy between individual benchmark programs, (2) the size, completeness, density and granularity of benchmark suites, (3) the distribution of benchmark programs in a program space, and (4) benchmark suite design and evolution strategies. The presented method can be used for designing a universal benchmark suite as the next generation of SPEC benchmarks.
An empirical study on how program layout affects cache miss rates
Authors: Jeffrey P. Bradford, Russell Quong
Venue: ACM SIGMETRICS Performance Evaluation Review (1999)

Cache miss rates are quoted for a specific program, cache configuration, and input set; the effect of program layout on the miss rate has largely been ignored. This paper examines the miss variation, that is, the variation in the miss rate for instruction and data caches resulting from randomly generated layouts; the layouts were generated by changing the order of the modules on the command line when linking. This analysis is performed for several cache sizes, lines sizes, set-associativities, input sets, compiler versions, and optimization levels for five programs in the SPEC92 benchmark suite. Miss rates were observed that varied from 60% to 180% of the mean miss rate. We did not observe any consistently good layouts across different parameters; in contrast, several layouts were consistently bad. Overall, cache line size and input set has little effect on the miss variation, while increasing the cache size (i.e. decreasing the miss rate), decreasing the set-associativity, or increasing the optimization level increases the miss variation. For a direct-mapped cache, the results in this paper call into question the validity of using a single layout (i) to determine the miss rate of a given program, (ii) to determine how a given compiler optimization affects the miss rate, and (iii) to make architecture design decisions based on the miss rate.
Comparative Dynamics in Perfect-Foresight Models
Authors: Lex Meijdam, Marijn Verhoeven
Venue: Computational Economics (1998)

This paper analyzes the technique of comparative dynamics (Judd, 1982) for the computation of the impact of perturbations on a steady state in a perfect-foresight model. The accuracy of this technique is demonstrated by numerical simulation experiments. Moreover, the technique is generalized to discrete-time models.
Understanding Similarity: A Joint Project for Psychology,Case-Based Reasoning, and Law
Authors: Ulrike Hahn, Nick Chater
Venue: Artificial Intelligence Review (1998)

Case-based Reasoning (CBR) began as a theory of human cognition, but has attracted relatively little direct experimental or theoretical investigation in psychology. However, psychologists have developed a range of instance-based theories of cognition and have extensively studied how similarity to past cases can guide categorization of new cases. This paper considers the relation between CBR and psychological research, focussing on similarity in human and artificial case-based reasoning in law. We argue that CBR, psychology and legal theory have complementary contributions to understanding similarity, and describe what each offers. This allows us to establish criteria for assessing existing CBR systems in law and to establish what we consider to be the crucial goals for further research on similarity, both from a psychological and a CBR perspective.
Computational properties of metaquerying problems
Authors: F. Angiulli, R. Ben-Eliyahu-Zohary, L. Palopoli, G. B. Ianni
Venue: Proceedings of the nineteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems (2000)

Metaquerying is a datamining technology by which hidden dependencies among several database relations can be discovered. This tool has already been successfully applied to several real-world applications. Recent papers provide only very preliminary results about the complexity of metaquerying. In this paper we define several variants of metaquerying that encompass, as far as we know, all variants defined in the literature. We study both the combined complexity and the data complexity of these variants. We show that, under the combined complexity measure, metaquerying is generally intractable (unless P=NP), but we are able to single out some tractable interesting metaquerying cases (whose combined complexity is LOGCFL-complete). As for the data complexity of metaquerying, we prove that, in general, this is in P, but lies within AC0 in some interesting cases. Finally, we discuss the issue of equivalence between metaqueries, which is useful for optimization purposes.
Software engineering teaching: a &ldquo;Docware&rdquo; approach
Authors: Daniel Deveaux, Regis Fleurquin, Patrice Frison
Venue: ACM SIGCSE Bulletin (1999)

The software engineering teaching is a true challenge. Indeed software engineering technology is only justified for large projects or long-term applications maintenance ; aspects impossible to show at the time of introductory course.In order to circumvent these difficulties, we propose a new approach of software development teaching which we called "Docware". It is a documentation centered process: the software product is no longer regarded as a source file that is documented afterwards, but as a set of documents whose source file is one product among others.After having specified our teaching objectives, we describe this approach which uses new tools that we developed and used for several years. A report of the use of this approach concludes this paper.
Volumetric Deformation Analysis Using Mechanics-Based Data Fusion: Applications in Cardiac Motion Recovery
Authors: Pengcheng Shi, Albert J. Sinusas, R. Todd Constable, James S. Duncan
Venue: International Journal of Computer Vision (1999)

Non-rigid motion estimation from image sequences is essential in analyzing and understanding the dynamic behavior of physical objects. One important example is the dense field motion analysis of the cardiac wall, which could potentially help to better understand the physiological processes associated with heart disease and to provide improvement in patient diagnosis and treatment. In this paper, we present a new method of estimating volumetric deformation by integrating intrinsic instantaneous velocity data with geometrical token displacement information, based upon continuum mechanics principles. This object-dependent approach allows the incorporation of physically meaningful constraints into the ill-posed motion recovery problem, and the integration of the two disparate but complementary data sources overcomes some of the limitations of the single-image-source-based motion estimation approaches.
Uniform characterizations of complexity classes
Authors: Heribert Vollmer
Venue: ACM SIGACT News (1999)

In the past few years, generalized operators (a. k. a. leaf languages) in the context of polynomial-time machines, and gates computing arbitrary groupoidal functions in the context of Boolean circuits, have raised much interest. We survey results from both areas, point out connections between them, and present relationships to a generalized quantifier concept from finite model theory.
High-Resolution Nonoscillatory Central Schemes with Nonstaggered Grids for Hyperbolic Conservation Laws
Authors: G.-S. Jiang, D. Levy, C.-T. Lin, S. Osher, E. Tadmor
Venue: SIAM Journal on Numerical Analysis (1998)

We present a general procedure to convert schemes which are based on staggered spatial grids into nonstaggered schemes. This procedure is then used to construct a new family of nonstaggered, central schemes for hyperbolic conservation laws by converting the family of staggered central schemes recently introduced in [H. Nessyahu and E. Tadmor, J. Comput. Phys., 87 (1990), pp. 408--463; X. D. Liu and E. Tadmor, Numer. Math., 79 (1998), pp. 397--425; G. S. Jiang and E. Tadmor, SIAM J. Sci. Comput., 19 (1998), pp. 1892--1917]. These new nonstaggered central schemes retain the desirable properties of simplicity and high resolution, and in particular, they yield Riemann-solver-free recipes which avoid dimensional splitting. Most important, the new central schemes avoid staggered grids and hence are simpler to implement in frameworks which involve complex geometries and boundary conditions.
Evaluation of Methods for Ridge and Valley Detection
Authors: Antonio M. López, Felipe Lumbreras, Joan Serrat, Juan J. Villanueva
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1999)

Ridges and valleys are useful geometric features for image analysis. Different characterizations have been proposed to formalize the intuitive notion of ridge/valley. In this paper, we review their principal characterizations and propose a new one. Subsequently, we evaluate these characterizations with respect to a list of desirable properties and their purpose in the context of representative image analysis tasks.
Using formal methods for teaching software engineering: a tool-based approach
Authors: P. Ciancarini, C. Mascolo
Venue: Annals of Software Engineering (1999)

In this paper we describe and review the course plan and syllabus we use in a course on formal methods in software engineering currently included in the degree in Informatics of the Faculty of Sciences at the University of Bologna. The course matches the theory of formal methods with their practice based on actual tool usage. In fact, the course is centered upon a project whose main goal is to let students learn some formal specification techniques, all supported by specific tools. The students use well&dash;known notations for both requirements specification and formal design. The formal methods we use are based on the Z notation for requirements specification and on the Larch family of languages for design specifications.
Iterative Methods of Solving Stochastic Convex Feasibility Problems andApplications
Authors: Dan Butnariu, Alfredo N. Iusem, Regina S. Burachik
Venue: Computational Optimization and Applications (2000)

The stochastic convex feasibility problem (SCFP) is the problem of finding almost common points of measurable families of closed convex subsets in reflexive and separable Banach spaces. In this paper we prove convergence criteria for two iterative algorithms devised to solve SCFPs. To do that, we first analyze the concepts of Bregman projection and Bregman function with emphasis on the properties of their local moduli of convexity. The areas of applicability of the algorithms we present include optimization problems, linear operator equations, inverse problems, etc., which can be represented as SCFPs and solved as such. Examples showing how these algorithms can be implemented are also given.
A comparison of real-time object-oriented modeling methods ROOM and OCTOPUS
Authors: Guilan Dai, Baowen Xu
Venue: ACM SIGPLAN Notices (1999)

ROOM and OCTOPUS are two real-time object-oriented modeling methods used commonly. The paper analyses and compares ROOM and OCTOPUS based on details where philosophies of both methods are in sharper contrast, such as model representation, class and object and inheritance, concurrency, and state charts.
Information systems and culture: applying &ldquo;stages of growth&rdquo; concepts to development administration
Authors: Robert D. Galliers, Shrin Madon, Rizwan Rashid
Venue: Information Technology for Development (1998)

This paper examines how cultural factors influence the rate at which individuals adopt technology to assist them in their duties. In order to achieve this, we review usage of the stages of growth model of information systems development in organisations which has been applied in the context of western and non-western organisations in various parts of the world. We then apply the model to the context of development administration where information technology interventions are becoming pervasive but where the inherent traditional cultural characteristics are fundamentally at variance with those of information technology practitioners. The case study we present is that of the implementation of information systems in the Karachi Development Authority (KDA). The findings highlight the utility and limitations of the stages of growth model in terms of its ability to accommodate the inherent cultural characteristics of KDA. While such knowledge will have value for information technology practitioners within their own societies, we contend that it will become even more valuable for practitioners from western cultures in applying technology solutions to development administration.
Eigenvalue Locations of Generalized Companion Predictor Matrices
Authors: Licio H. Bezerra, Fermin S. V. Bazán
Venue: SIAM Journal on Matrix Analysis and Applications (1998)

Generalized predictor companion matrices arise in the linear prediction approach for the fit of a weighted sum of $n$ exponentials to a given set of data points. They are special solutions of matrix equations of the type ${\sf H}(l+p)\, {\sf S}={\sf H}(l)$, where for each $l\ge 0$ ${\sf H}(l)$ is an $M\times N$ Hankel matrix obtained from this data ($M\ge N>n$). We discuss in this paper results about the eigenvalue locations of this class of solutions by means of linear algebra techniques. An application of these results in the case that all the exponents have either negative or positive real parts is that the n exponentials can correspond to eigenvalues which are outside the unit circle depending on the choice of generalized predictor companion matrices. The other (N-n) eigenvalues of these matrices always lie inside the unit circle and approach zero when p increases. This separation can facilitate their numerical calculation.
Automatic Recognition of Human Walking in Monocular Image Sequences
Authors: Jia-Ching Cheng, José M. F. Moura
Venue: Journal of VLSI Signal Processing Systems (1998)

In numerous content-based video applications, it is important to extract from a video sequence a representation for humans in motion. This task is difficult, because humans are not rigid objects and they are capable of performing a wide variety of actions. However, often, human movements can be categorized into repetitive and rhythmic patterns of motion. Identifying the motion pattern of a human significantly alleviates the task of construction of its representation. We propose here a model-based recognition of the generic posture of human walking in dynamic scenes. We model the human body as an articulated object connected by joints and rigid parts, and model the human walking as a periodic motion. The recognition task is to fit the model walker sequence to the walker in the live video (data walker sequence). We achieve this by determining the period of the data walker sequence and finding its phase with respect to the model walker sequence. We present promising results of how our system performs with a live video sequence.
Index research (panel session): forest or trees?
Venue: ACM SIGMOD Record (2000)

Indexes and access methods have been a staple of database research &mdash; and indeed of computer science in general &mdash; for decades. A glance at the contents of this year's SIGMOD and PODS proceedings shows another bumper crop of indexing papers.Given the hundreds of indexing papers published in the database literature, a pause for reflection seems in order. From a scientific perspective, it is natural to ask why definitive indexing solutions have eluded us for so many years. What is the grand challenge in indexing? What basic complexities or intricacies underlie this large body of work? What would constitute a successful completion of this research agenda, and what steps will best move us in that direction? Or is it the case that the problem space branches in so many ways that we should expect to continuously need to solve variants of the indexing problem?From the practitioner's perspective, the proliferation of indexing solutions in the literature may be more confusing than helpful. Comprehensively evaluating the research to date is a near-impossible task. An evaluation has to include both functionality (applicability to the practitioner's problem, integration with other data management services like buffer management, query processing and transactions) as well as performance for the practitioner's workloads. Unfortunately, there are no standard benchmarks for advanced indexing problems, and there has been relatively little work on methodologies for index experimentation and customization. How should the research community promote technology transfer in this area? Are the new extensibility interfaces in object-relational DBMSs conducive to this effort?
An axiomatic approach to deciding query safety in deductive databases
Authors: Michael Kifer, Raghu Ramakrishnan, Avi Silberschatz
Venue: Proceedings of the seventh ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1988)

A database query is safe if its result consists of a finite set of tuples. If a query is expressed using a set of pure Horn Clauses, the problem of determining query safety is, in general, undecidable. In this paper we consider a slightly stronger notion of safety, called supersafety, for Horn databases in which function symbols are replaced by the abstraction of infinite relations with finiteness constraints [Ramarkrishman et. al 87] We show that the supersafety problem is not only decidable, but also axiomatizable, and the axiomatization yields an effective decision procedure. Although there are safe queries which are not supersafe, we demonstrate that the latter represent quite a large and nontrivial portion of the safe of all safe queries
Procedure Based Program Compression
Authors: Darko Kirovski, Johnson Kin, William H. Mangione-Smith
Venue: International Journal of Parallel Programming (1999)

Cost and power consumption are two of the most important design factors for many embedded systems, particularly consumer devices. Products such as Personal Digital Assistants, pagers with integrated data services, and smart phones have fixed performance requirements but unlimited appetites for reduced cost and increased battery life. Program compression is one technique that can be used to attack both of these problems. Compressed programs require less memory, thus reducing the cost of both direct materials and manufacturing. Furthermore, by relying on compressed memory, the total number of memory references is reduced. This reduction saves power by lowering the traffic on high capacitance buses. This paper will discuss a new approach to implementing transparent program compression that requires little or no hardware support. Procedures are compressed individually, and a directory structure is used to bind them together at runtime. Decompressed procedures are explicitly cached in ordinary RAM as complete units, thus resolving references within each procedure. This approach has been evaluated on a set of 25 embedded multimedia and communications applications, and results in an average memory reduction of 40% with a runtime performance overhead of 10%.
Powering by a Table Look-Up and a Multiplication with Operand Modification
Authors: Naofumi Takagi
Venue: IEEE Transactions on Computers (1998)

An efficient method for generating a power of an operand, i.e., Xp for an operand X and a given p, is proposed. It is applicable to ps in the form of ±2k, where k is any integer and of $\pm 2^{k_1}\ \pm 2^{-k_2},$ where k1 is any integer and k2 is any nonnegative integer. The reciprocal, the square root, the reciprocal square root, the reciprocal square, the reciprocal cube, and so forth are included. The method is a modification of the piecewise linear approximation. A power of an operand is generated through a table look-up and a multiplication with operand modification. The same accuracy is achieved as the piecewise linear approximation. The multiplication and an addition required for the piecewise linear approximation are replaced by only one double-sized multiplication with a slight modification of the operand and, hence, one clock cycle may be reduced. The required table size is reduced because only one coefficient instead of two has to be stored.