Exact and Approximate Algorithms for Assignment Problems in Distributed Systems

Exact and Approximate Algorithms for Assignment Problems in Distributed Systems
Author: David Fernandez-Baca
Publisher:
Total Pages: 22
Release: 1992
Genre: Distributed parameter systems
ISBN:

Abstract: "We present exact dynamic programming algorithms for two variants of the task assignment problem on distributed systems: (1) finding a minimum-cost assignment when one of the processors has limited memory and (2) finding an assignment that minimizes the maximum processor load. These procedures lead to approximation schemes for the case where the communication graph is a partial k-tree. In contrast to these results, we show that, for arbitrary graphs, no fully polynomial time approximation schemes exist unless P = NP. Finally, we discuss implementation details for our algorithms and summarize our experimental results."

Approximation Algorithms for Certain Assignment Problems in Distributed Systems

Approximation Algorithms for Certain Assignment Problems in Distributed Systems
Author: Iowa State University. Dept. of Computer Science
Publisher:
Total Pages: 44
Release: 1991
Genre: Distributed parameter systems
ISBN:

Abstract: "We consider two variants of the task assignment problem for distributed systems. The first is the problem of finding a minimum cost assignment when one of the processors has a limited memory. The second is the problem of finding an assignment that minimizes the maximum processor load. Both problems are NP-hard, even if the communication graph is a tree. We present exact algorithms and approximation schemes for these problems for the case where the communication graph is a partial k-tree. Faster algorithms are presented for the case of trees with uniform costs. We also show that, if the communication graph is unrestricted, there is no fully polynomial-time approximation scheme for the memory-constrained problem unless P = NP."

Iterative Methods in Combinatorial Optimization

Iterative Methods in Combinatorial Optimization
Author: Lap Chi Lau
Publisher: Cambridge University Press
Total Pages: 255
Release: 2011-04-18
Genre: Computers
ISBN: 1139499394

With the advent of approximation algorithms for NP-hard combinatorial optimization problems, several techniques from exact optimization such as the primal-dual method have proven their staying power and versatility. This book describes a simple and powerful method that is iterative in essence and similarly useful in a variety of settings for exact and approximate optimization. The authors highlight the commonality and uses of this method to prove a variety of classical polyhedral results on matchings, trees, matroids and flows. The presentation style is elementary enough to be accessible to anyone with exposure to basic linear algebra and graph theory, making the book suitable for introductory courses in combinatorial optimization at the upper undergraduate and beginning graduate levels. Discussions of advanced applications illustrate their potential for future application in research in approximation algorithms.

Introduction to Distributed Self-Stabilizing Algorithms

Introduction to Distributed Self-Stabilizing Algorithms
Author: Karine Altisen
Publisher: Springer Nature
Total Pages: 147
Release: 2022-05-31
Genre: Computers
ISBN: 3031020138

This book aims at being a comprehensive and pedagogical introduction to the concept of self-stabilization, introduced by Edsger Wybe Dijkstra in 1973. Self-stabilization characterizes the ability of a distributed algorithm to converge within finite time to a configuration from which its behavior is correct (i.e., satisfies a given specification), regardless the arbitrary initial configuration of the system. This arbitrary initial configuration may be the result of the occurrence of a finite number of transient faults. Hence, self-stabilization is actually considered as a versatile non-masking fault tolerance approach, since it recovers from the effect of any finite number of such faults in an unified manner. Another major interest of such an automatic recovery method comes from the difficulty of resetting malfunctioning devices in a large-scale (and so, geographically spread) distributed system (the Internet, Pair-to-Pair networks, and Delay Tolerant Networks are examples of such distributed systems). Furthermore, self-stabilization is usually recognized as a lightweight property to achieve fault tolerance as compared to other classical fault tolerance approaches. Indeed, the overhead, both in terms of time and space, of state-of-the-art self-stabilizing algorithms is commonly small. This makes self-stabilization very attractive for distributed systems equipped of processes with low computational and memory capabilities, such as wireless sensor networks. After more than 40 years of existence, self-stabilization is now sufficiently established as an important field of research in theoretical distributed computing to justify its teaching in advanced research-oriented graduate courses. This book is an initiation course, which consists of the formal definition of self-stabilization and its related concepts, followed by a deep review and study of classical (simple) algorithms, commonly used proof schemes and design patterns, as well as premium results issued from the self-stabilizing community. As often happens in the self-stabilizing area, in this book we focus on the proof of correctness and the analytical complexity of the studied distributed self-stabilizing algorithms. Finally, we underline that most of the algorithms studied in this book are actually dedicated to the high-level atomic-state model, which is the most commonly used computational model in the self-stabilizing area. However, in the last chapter, we present general techniques to achieve self-stabilization in the low-level message passing model, as well as example algorithms.