Compositional competitiveness for distributed algorithms

We define a measure of competitive performance for distributed algorithms based on throughput, the number of tasks that an algorithm can carry out in a fixed amount of work. This new measure complements the latency measure of Ajtai et al., which measures how quickly an algorithm can finish tasks that start at specified times. The novel feature of the throughput measure, which distinguishes it from the latency measure, is that it is compositional: it supports a notion of algorithms that are competitive relative to a class of subroutines, with the property that an algorithm that is k-competitive relative to a class of subroutines, combined with an l-competitive member of that class, gives a combined algorithm that is kl-competitive. In particular, we prove the throughput-competitiveness of a class of algorithms for collect operations, in which each of a group of n processes obtains all values stored in an array of n registers. Collects are a fundamental building block of a wide variety of shared-memory distributed algorithms, and we show that several such algorithms are competitive relative to collects. Inserting a competitive collect in these algorithms gives the first examples of competitive distributed algorithms obtained by composition using a general construction.Comment: 33 pages, 2 figures; full version of STOC 96 paper titled "Modular competitiveness for distributed algorithms.

The Isis project: Fault-tolerance in large distributed systems

This final status report covers activities of the Isis project during the first half of 1992. During the report period, the Isis effort has achieved a major milestone in its effort to redesign and reimplement the Isis system using Mach and Chorus as target operating system environments. In addition, we completed a number of publications that address issues raised in our prior work; some of these have recently appeared in print, while others are now being considered for publication in a variety of journals and conferences

Transactions Everywhere

Arguably, one of the biggest deterrants for software developers who might otherwise choose to write parallel code is that parallelism makes their lives more complicated. Perhaps the most basic problem inherent in the coordination of concurrent tasks is the enforcing of atomicity so that the partial results of one task do not inadvertently corrupt another task. Atomicity is typically enforced through locking protocols, but these protocols can introduce other complications, such as deadlock, unless restrictive methodologies in their use are adopted. We have recently begun a research project focusing on transactional memory [18] as an alternative mechanism for enforcing atomicity, since it allows the user to avoid many of the complications inherent in locking protocols. Rather than viewing transactions as infrequent occurrences in a program, as has generally been done in the past, we have adopted the point of view that all user code should execute in the context of some transaction. To make this viewpoint viable requires the development of two key technologies: effective hardware support for scalable transactional memory, and linguistic and compiler support. This paper describes our preliminary research results on making “transactions everywhere” a practical reality.Singapore-MIT Alliance (SMA

Guidelines for the verification and validation of expert system software and conventional software: Bibliography. Volume 8

This volume contains all of the technical references found in Volumes 1-7 concerning the development of guidelines for the verification and validation of expert systems, knowledge-based systems, other AI systems, object-oriented systems, and conventional systems

Department of Computer Science Activity 1998-2004

This report summarizes much of the research and teaching activity of the Department of Computer Science at Dartmouth College between late 1998 and late 2004. The material for this report was collected as part of the final report for NSF Institutional Infrastructure award EIA-9802068, which funded equipment and technical staff during that six-year period. This equipment and staff supported essentially all of the department\u27s research activity during that period

Space for collaboration from non-western perspectives: Communication in a organization

The ontological and epistemological distinction made between the ‘Orient’ and the ‘Occident’ has been largely accepted as the starting point for elaborate accounts concerning the Orient, its people, culture, and mind. Particularly, such distinction has led to a fundamentally different philosophy of space and time in East and West. In most of the Eurocentric organization studies, space has been commodified and rationalized as absolute for the pursuit of governance and control which stands a sharp contrast to the East relativism perspective of space. As a result of intellectual imperialism, placing East in the West paradigm through borrowed material and the eyes of others is impractical. The lack of resonance of non-Western paradigm in communication study is an apparent gap to be filled. Therefore, this research aimed to examine affordance of organization space for collaboration from non-Western perspectives. A six-month ethnographic fieldwork was conducted in an ICT company. Data were collected through participant observation, semi-structured and unstructured interview with 42 Chinese research analysts, documentary sources and material artefacts. Findings identified five underlying key values in non-Western communicative behaviour pertinent to Chinese cardinal value of harmony which emphasized on interrelationship, interdependence and mutuality. Results also demonstrated a cyclical view of space and the notion of spatial affordance afforded sense of community and sociality which making space a ‘destination’ for togetherness and cohesiveness. Lastly, the research contributed insights to study spatial production from a non-Western cyclical view rather than the long (mis) representation of linear way

Histogram techniques for cost estimation in query optimization.

Yu Xiaohui.Thesis (M.Phil.)--Chinese University of Hong Kong, 2001.Includes bibliographical references (leaves 98-115).Abstracts in English and Chinese.Chapter 1 --- Introduction --- p.1Chapter 2 --- Related Work --- p.6Chapter 2.1 --- Query Optimization --- p.6Chapter 2.2 --- Query Rewriting --- p.8Chapter 2.2.1 --- Optimizing Multi-Block Queries --- p.8Chapter 2.2.2 --- Semantic Query Optimization --- p.13Chapter 2.2.3 --- Query Rewriting in Starburst --- p.15Chapter 2.3 --- Plan Generation --- p.16Chapter 2.3.1 --- Dynamic Programming Approach --- p.16Chapter 2.3.2 --- Join Query Processing --- p.17Chapter 2.3.3 --- Queries with Aggregates --- p.23Chapter 2.4 --- Statistics and Cost Estimation --- p.24Chapter 2.5 --- Histogram Techniques --- p.27Chapter 2.5.1 --- Definitions --- p.28Chapter 2.5.2 --- Trivial Histograms --- p.29Chapter 2.5.3 --- Heuristic-based Histograms --- p.29Chapter 2.5.4 --- V-Optimal Histograms --- p.32Chapter 2.5.5 --- Wavelet-based Histograms --- p.35Chapter 2.5.6 --- Multidimensional Histograms --- p.35Chapter 2.5.7 --- Global Histograms --- p.37Chapter 3 --- New Histogram Techniques --- p.39Chapter 3.1 --- Piecewise Linear Histograms --- p.39Chapter 3.1.1 --- Construction --- p.41Chapter 3.1.2 --- Usage --- p.43Chapter 3.1.3 --- Error Measures --- p.43Chapter 3.1.4 --- Experiments --- p.45Chapter 3.1.5 --- Conclusion --- p.51Chapter 3.2 --- A-Optimal Histograms --- p.54Chapter 3.2.1 --- A-Optimal(mean) Histograms --- p.56Chapter 3.2.2 --- A-Optimal(median) Histograms --- p.58Chapter 3.2.3 --- A-Optimal(median-cf) Histograms --- p.59Chapter 3.2.4 --- Experiments --- p.60Chapter 4 --- Global Histograms --- p.64Chapter 4.1 --- Wavelet-based Global Histograms --- p.65Chapter 4.1.1 --- Wavelet-based Global Histograms I --- p.66Chapter 4.1.2 --- Wavelet-based Global Histograms II --- p.68Chapter 4.2 --- Piecewise Linear Global Histograms --- p.70Chapter 4.3 --- A-Optimal Global Histograms --- p.72Chapter 4.3.1 --- Experiments --- p.74Chapter 5 --- Dynamic Maintenance --- p.81Chapter 5.1 --- Problem Definition --- p.83Chapter 5.2 --- Refining Bucket Coefficients --- p.84Chapter 5.3 --- Restructuring --- p.86Chapter 5.4 --- Experiments --- p.91Chapter 6 --- Conclusions --- p.95Bibliography --- p.9

Air Force Institute of Technology Research Report 1997

This report summarizes the research activities of the Air Force Institute of Technology\u27s Graduate School of Engineering and the Graduate School of Logistics and Acquisition Management. It describes research interests and faculty expertise; list student theses/dissertations; identifies research sponsors and contributions; and outlines the procedure for contacting either school