ppxscal/embedding_network huggingface dataset:
pCube: Update-Efficient Online Aggregation with Progressive Feedback and Error Bounds
Authors: M. Riedewald, D. Agrawal, A. E Abbadi
Venue:  (2000)

Data Cubes are used in large data warehouses as a tool for online aggregation of information. Typically, online aggregation is supported by specifying a range query over a multidimensional data cube. As the number of dimensions increases, supporting efficient range queries as well as updates to the data cube becomes difficult. Another problem that arises with increased dimensionality is the sparseness of the data space. In this paper we develop a new data structure referred to as the pCube (data cube for progressive querying), to support efficient querying and updating of multidimensional data cubes in large data warehouses. pCube provides intermediate results with absolute error bounds (to allow trading accuracy for fast response time), efficient updates, scalability with increasing dimensionality, and pre-aggregation to support large range queries. We present both a general solution and an implementation of pCube and report the results of experimental evaluations.
Architecture and Implementation of the Active Object-OrientedDatabase Management System SAMOS
Authors: Andreas Geppert, Stella Gatziu, Klaus R. Dittrich, Hans Fritschi, Anca Vaduva
Venue:  (1995)

The architecture and the implementation of the active, object- oriented database management system SAMOS are described. SAMOS is a research prototype extending a commercial object-oriented database management system with reactive behavior specified in the form of event- condition rules. This paper describes the various components of SAMOS for event detection, rule management, rule execution, and transaction management, and explains how they work and interact upon rule definition and execution. The current architecture of SAMOS is evaluated, experiences with the layered approach are described, and drawbacks are identified.
Deferred Data-Flow Analysis
Authors: Shamik Sharma, Anurag Acharya, Joel Saltz
Venue:  (1998)

Loss of precision due to the conservative nature of compile-time dataflow analysis impacts a wide variety of optimizations. In this paper, we propose a general framework which combines compile-time analysis with limited runtime analysis to improve the precision of dataflow information at performance-critical points in the program. This technique, which we refer to as deferred dataflow analysis (DDFA), performs most of the analysis at compile-time but defers the final stages of the analysis till runtime when additional information is available. We present algorithms for construction of region summary functions and for composition and application of these functions. Dividing the analysis in this manner raises two concerns: (1) is it possible to generate correct and compact summary functions for regions? (2) is it possible to correctly and efficiently compose and apply these functions at run-time? To address these concerns, we show that DDFA terminates, is safe and that its results are at least as good as a compile-time meets-over-all-paths solution. To address concerns regarding the size of the data-structures used to communicate information from the compiler to the runtime system, we present space requirements of DDFA in the context of three different backward data-flow analyses. To address concerns regarding the runtime overhead of DDFA and to demonstrate the ability of DDFA to optimize heavy-weight operations, we present results from the application of DDFA for two of these analyses.
User-controlled link adaptation
Authors: Theophanis Tsandilas, m. c. schraefel
Venue: Proceedings of the fourteenth ACM conference on Hypertext and hypermedia (2003)

This paper introduces an adaptable hypermedia approach applied to adaptive link annotation techniques. This approach suggests that the combination of direct manipulation with automated link annotation affords greater user control over page adaptation. In turn, this direct control better supports user focus in information discovery tasks. Unlike adaptive-only systems, our approach lets users both define multiple topics of interest and then manipulate how these topics' associated links are presented in a page. We discuss how the approach can be applied both to pages viewed as well as to the user's history list, thereby relieving users from the task of either adding to or organizing bookmarks. We describe the prototype developed to support these manipulations, as well as the adaptive architecture developed to support these controls.
A Case Study in Exploiting Layers to Optimize Scientific Software
Authors: Samuel Z. Guyer, Calvin Lin
Venue:  (2001)

This paper presents a case study in improving the performance of layered scientific software using library-level optimization. We augment our previous work to include a notion of layers, and apply the technique to the three layers that make up the PLAPACK parallel linear algebra library -- a global application level, an internal layer, and an MPI message passing layer. We show how significant performance improvements of 10% to 180% for large matrices and 36% to 600% for small matrices are possible for four PLAPACK applications. Our approach works because it first exploits layer boundaries to facilitate high-level program analysis and optimization, and then systematically dissolves layer boundaries to expose new optimization opportunities. This work is presented in the context of the Broadway compiler system, which uses an annotation language to capture semantic information about the abstractions present in software libraries.
A General Approach to Multiprocessor Scheduling
Authors: Sung J Kim
Venue:  (1988)

As a variety of general-purpose multiprocessor systems have been recently designed and built, multiprocessor scheduling is becoming increasingly important. Multiprocessor scheduling is a technique to exploit the underlying hardware in a multiprocessor system so that parallelism existing in an application program can be fully utilized and interprocessor communication time can be minimized. Traditionally, most research on multiprocessor scheduling has focused on the development of specific scheduling strategies to take advantage of unique characteristics of a specific multiprocessor system or application program. In this thesis, we define and characterize scheduling techniques and related heuristic mapping algorithms which are applicable to a spectrum of multiprocessor systems and a broad class of application programs. The fundamental idea we use is that multiprocessor scheduling can be regarded as a series of mappings from a computation graph (representing an application program) to a virtual architecture graph (representing an optimal architecture for the program) and eventually to a physical architecture graph (representing a target multiprocessor system). We propose linear clustering and linear cluster merging as effectual heuristics. After linear clustering and merging, the computation graph is transformed into a virtual architecture graph. This graph represents an optimal architecture which compromises between two conflicting goals, minimization of interprocessor communication and maximization of potential parallelism, and satisfies the other goals, throughput enhancement and workload balance, relatively well. Then we develop two efficient scheduling algorithms which map the optimal architecture graph onto a physical architecture graph which may represent either a homogeneous or a heterogeneous multiprocessor system. These algorithms rely not only on local information but also on limited global information. Finally, we present the result of performance evaluation of the mapping algorithms on an Intel iPSC with 32 processors and a Sequent Balance with 10 processors.
Commutativity Analysis: A New Technique for Automatically Parallelizing Serial Programs
Authors: Martin C. Rinard, Pedro Diniz
Venue:  (1994)

This paper introduces a new analysis technique, commutativity analysis, for automatically parallelizing programs written in sequential, imperative programming languages. Commutativity analysis aggregates both data and computation into larger grain units. It then analyzes the computation at this granularity to discover when pieces of the computation commute (i.e. generate the same result regardless of the order in which they execute). If all of the operations required to perform a given computation commute, the compiler can automatically generate parallel code. This approach differs from standard approaches based on data dependence analysis in that it generates parallel programs that may violate the data dependences of the original serial program. Commutativity analysis can therefore automatically parallelize programs that are inherently beyond the reach of any compiler that preserves the data dependences. In this paper we formally define a set of conditions that the compiler can use to automatically detect commuting operations, prove that if operations meet these conditions then their executions commute and show how to exploit the commutativity information to automatically generate parallel code.
A Simple Theorem Prover Based on symbolic Trajectory Evaluation and OBDD''s
Authors: Scott Hazelhurst, Carl Seger
Venue:  (1993)

Formal hardware verification based on symbolic trajectory evaluation shows considerable promise in verifying medium to large scale VLSI designs with a high degree of automation. However, in order to verify today''s designs, a method for composing partial verification results is needed. One way of accomplishing this is to use a general purpose theorem prover to combine the verification results obtained by other tools. However, a special purpose theorem prover is more attractive since it can more easily exploit symbolic trajectory evaluation (and may be easier to use). Consequently we explore the possibility of developing a much simpler, but more tailor made, theorem prover designed specifically for combining verification results based on trajectory evaluation. In the paper we discuss the underlying inference rules of the prover as well as more practical issues regarding the user interface. We finally conclude with a couple of examples in which we are able to verify designs that could not have been verified directly. In particular, the complete verification of a 64 bit multiplier takes approximately 15 minutes on a Sparc 10 machine.
A MORE EFFICIENT DISTANCE VECTOR ROUTING ALGORITHM
Authors: Zhengyu Xu, Sa Dai, J. J. Garcia-Luna
Venue:  (1997)

A more efficient distance vector routing algorithm (EDVA) for computer networks is presented. EDVA is based on enhancements to two classes of distance vector algorithms, the path finding algorithms that report complete path information incrementally, and the diffusing update algorithm (DUAL) which is used in Cisco''s Enhanced Interior Gateway Routing Protocol (EIGRP) and is based on diffusing computations for internodal synchronization. EDVA operates by specifying a distance, a feasible distance, a predecessor and diffusing hops to each destination. This information is used together with diffusing computations of limited span to avoid routing-table loops. The correctness of EDVA is discussed. The benefits in EDVA compared with DUAL and path finding algorithms are illustrated with simple examples of its general cases. Briefly, the advantages of EDVA are reducing the routing converge time and the number of packets for routing information. Some parameters used in routing-table updates, the diffusing hop count in particular, can be adjusted based on the past information of the behaviors and topology of the network. This further improves EDVA''s performance by allowing to adapt to the operational characteristics of the network.
Interface Negotiation and Efficient Reuse: A Relaxed Theory of the Component Object Model
Authors: Kevin J. Sullivan, Mark Marchukov
Venue:  (1997)

Reconciling requirements for (1) the efficient integration of independently developed and evolving components and (2) the evolution of systems built from such components requires novel architectural styles, standards and idioms. Traditional object-oriented approaches have proven inadequate. Two important new mechanisms supporting integration and evolution are dynamic interface negotiation and aggregation, an approach to efficient composition. Both feature prominently in the Component Object Model (COM), a de facto standard providing the architectural foundation for many important systems. Because these are important mechanisms in general, and because they are central to COM in particular, it is essential that engineers be able to reason effectively about them. In earlier work (Sullivan et al. 1997), we showed that reasoning about them is hard and that formal mathematical theories of such mechanisms can provide a foundation for effective reasoning. In this paper we present a new theory of interface negotiation and aggregation in COM. Our new theory is based on a relaxed interpretation of the COM specification. Our earlier theory reflected an interpretation of the specification in which components had to be designed to follow COM-specified rules for interface negotiation and aggregation under any possible usage. Our new, strictly weaker theory requires only that actual system executions not manifest any violations of the rules. Architectural styles using mediators that we showed to be untenable under the earlier theory are tenable under this one provided the designers follow certain rules. We derive these necessary and sufficient conditions for legal use of interface negotiation in the presence of aggregation. Our results provide a basis for documenting what engineers must not do to use aggregation and interface negotiation properly.
Scheduling Coarse-Grain Iterative Task Computation on Message-Passing Architectures
Authors: T. Yang
Venue:  (1994)

Scheduling task computation and predicting its performance on message-passing architectures are important for program parallelization. In this paper we consider the scheduling of a weighted iterative task graph (ITG) in the presence of communication overhead. An ITG represents a sequence of parallel task computation. Each iteration contains the execution of a set of tasks and there exists task dependence within an iteration and between iterations. We provide a lower bound for optimal scheduling when the weights of iterative task graphs change monotonically in the course of iterations. We devise a valid schedule without searching task instances of all iterations and examine the asymptotic performance of this schedule compared to an optimal solution. Finally, we present case studies and experimental results on nCUBE-2 to verify our solutions. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
Educational portal white paper
Authors: Ali Jafari
Venue: Designing portals: opportunities and challenges (2003)

This white paper conceptualizes and discusses the design and application of a super web portal for state or nationwide educational applications. The term "Educational Portal" refers to a web gateway environment that allows users with varied educational interests to access educational resources and information. The Educational Portal provides a collaborative environment where educators can find peers who share educational knowledge and creativity. It is also a "profile-based" web environment portal that can be totally personalized according to each user's needs and interests, providing each user with specialized "MyPortal" functionality.Many educational institutions are currently in the process of offering Web-based portals to their instructors and students. This might include services like course portal, library portal and campus portal. However, each of these portals offers services available within the institution only to the members of that institution. For instance, each portal can offer authenticated student and faculty access to courses, library materials and Student lnformation Systems in an institution. But there is no direct sharing of knowledge or resources between and among the members of various educational institutions.It now appears necessary to offer a state or nationwide single front door portal gateway where any and all learners, regardless of institutional affiliation, can gain access to educational and training information. It will provide an opportunity for educators and trainers to share resources, and information and to collaborate on the development, evaluation and sharing of educational modules. For instance, the gateway will include a portal environment where a teacher can share the use of a personally developed e-Learning module with other teachers in the same field and class rank at other schools, or with students and others who wish to use it in their learning environment.
HOMPACK90: A Suite of FORTRAN 90 Codes for Globally Convergent Homotopy Algorithms
Authors: Watson Layne T., Sosonkina Maria, Melville Robert C., Morgan Alexander P., Walker Homer F.
Venue:  (1996)

HOMPACK90 is a FORTRAN 90 version of the FORTRAN 77 package HOMPACK (Algorithm 652), a collection of codes for finding zeros or fixed points of nonlinear systems using globally convergent probability-one homotopy algorithms. Three qualitatively different algorithms - ordinary differential equation based, normal flow, quasi-Newton augmented Jacobian matrix - are provided for tracking homotopy zero curves, as well as separate routines for dense and sparse Jacobian matrices. A high level driver for the special case of polynomial systems is also provided. Changes to HOMPACK include numerous minor improvements, simpler and more elegant interfaces, use of modules, new end games, support for several sparse matrix data structures, and new iterative algorithms for large sparse Jacobian matrices.
Marriage Before Conquest: A Variation on the Divide \& Conquer Paradigm
Authors: David G. Kirkpatrick, Seidel Raimund
Venue:  (1983)

We present a new planar convex hull algorithm with worst case time complexity $O(n \log H)$ where $n$ is the size of the input set and $H$ is the size of the output set, i.e. the number ot vertices found to be on the hull. We also show that this algorithm is asymptotically worst case optimal on a rather realisic model of computation even if the complexity of the problem is measured in terms of input as well as output size. The algorithm relies on a variation of the divide-and-conquer paradigm which we call the ``marriage-before-conquest'''' principle and which appears to be interesting in its own right.
Developing Human-Computer Interface Models and Representation Techniques(Dialogue Management as an Integral Part of Software Engineering)
Authors: H. R Hartson, Deborah Hix, Thomas M. Kraly
Venue:  (1987)

The Dialogue Management Project at Virginia Tech is studying the poorly understood problem of human-computer dialogue development. This problem often leads to low usability in human-computer dialogues. The Dialogue Management Project approaches solutions to low usability in interfaces by addressing human-computer dialogue development as an integral and equal part of the total system development process. This project consists of two rather distinct, but dependent, parts. One is development of concepts for dialogue management, and the other is implementation of a dialogue management system (DMS) to evaluate these concepts. The goal of this paper is to describe our approach to the development of two of these conceptual aspects and how we oriented those toward the needs of practical implementation. The two conceptual aspects are (a) a structural, descriptive model of human-computer interaction, and (b) Techniques for representing both the behavioral (end-user''s) view and the constructional (developer''s) view of dialogue. The approach to their development was a technology transfer process that was part of a two-year university/industry research liaison between the Dialogue Management Project and IBM Federal Systems Division (FSD), now called Systems Integration Division. Part of this liaison was aimed at moving our research ideas and results into a real-world dialogue development environment. Following presentation of the technical problems and solutions, the paper concludes with a discussion of results of our liaison and by raising and addressing some questions of mutual interest that arose during our cooperative interaction.
The Case for Hierarchical Schedulers with Performance Guarantees
Authors: John Regehr, Jack Stankovic, Marty Humphrey
Venue:  (2000)

Audio and video applications, process control, agile manufacturing and even defense systems are using commodity hardware and operating systems to run combinations of real-time and non-real-time tasks. We propose an architecture that will allow a general-purpose operating system to schedule conventional and real-time tasks with diverse requirements, to provide flexible load isolation between applications, users, and accounting domains, and to enforce high-level policies about the allocation of CPU time. This is accomplished by implementing a dynamic, hierarchical scheduling infrastructure. The infrastructure is integrated with a resource manager that provides a level of indirection between resource requests and the scheduling hierarchy. A scheduling infrastructure separates scheduler code from the rest of the operating system. To demonstrate the utility of our architecture, we describe its application to three existing real-time schedulers. For each of the three, we show added flexibility while retaining the original scheduling guarantees.
Multiresolution Estimation of 2-d Disparity Using a Frequency Domain Approach
Authors: A. D. Calway, H. Knutsson, R. G. Wilson
Venue:  (1991)

An efficient algorithm for the estimation of the 2-d disparity between a pair of stereo images is presented. Phase based methods are extended to the case of 2-d disparities and shown to correspond to computing local correlation fields. These are derived at multiple scales via the frequency domain and a coarse-to-fine ''focusing'' strategy determines the final disparity estimate. Fast implementation is achieved by using a generalised form of wavelet transform, the multiresolution Fourier transform (MFT), which enables efficient calculation of the local correlations. Results from initial experiments on random noise stereo pairs containing both 1-d and 2-d disparities, illustrate the potential of the approach.
Diamonds are not a Minimum Weight Triangulation''s Best Friend
Authors: Prosenjit Bose, Luc Devroye, William Evans
Venue:  (1996)

Two recent methods have increased hopes of finding a polynomial time solution to the problem of computing the minimum weight triangulation of a set $S$ of $n$ points in the plane. Both involve computing what was believed to be a connected or nearly connected subgraph of the minimum weight triangulation, and then completing the triangulation optimally. The first method uses the light graph of $S$ as its initial subgraph. The second method uses the \lmt-skeleton of $S$. Both methods rely, for their polynomial time bound, on the initial subgraphs having only a constant number of components. Experiments performed by the authors of these methods seemed to confirm that randomly chosen point sets displayed this desired property. We show that there exist point sets where the number of components is linear in $n$. In fact, the expected number of components in either graph on a randomly chosen point set is linear in $n$, and the probability of the number of components exceeding some constant times $n$ tends to one.