The theory of directed graphs has developed enormously over recent decades, yet this book (first published in 2000) remains the only book to cover more than a small fraction of the results. New research in the field has made a second edition a necessity. Substantially revised, reorganised and updated, the book now comprises eighteen chapters, carefully arranged in a straightforward and logical manner, with many new results and open problems. As well as covering the theoretical aspects of the subject, with detailed proofs of many important results, the authors present a number of algorithms, and whole chapters are devoted to topics such as branchings, feedback arc and vertex sets, connectivity augmentations, sparse subdigraphs with prescribed connectivity, and also packing, covering and decompositions of digraphs. Throughout the book, there is a strong focus on applications which include quantum mechanics, bioinformatics, embedded computing, and the travelling salesman problem. Detailed indices and topic-oriented chapters ease navigation, and more than 650 exercises, 170 figures and 150 open problems are included to help immerse the reader in all aspects of the subject. Digraphs is an essential, comprehensive reference for undergraduate and graduate students, and researchers in mathematics, operations research and computer science. It will also prove invaluable to specialists in related areas, such as meteorology, physics and computational biology.

Digraphs Theory Algorithms And Applications

https://users.dimi.uniud.it/~antonio.dangelo/Robotica/2012/helper/leggedRobot/Ijspeert08NN.pdf

2008 Special Issue: Central pattern generators for locomotion control in animals and robots: A review

We give a deterministic algorithm for triangulating a simple polygon in linear time. The basic strategy is to build a coarse approximation of a triangulation in a bottom-up phase and then use the information computed along the way to refine the triangulation in a top-down phase. The main tools used are the polygon-cutting theorem, which provides us with a balancing scheme, and the planar separator theorem, whose role is essential in the discovery of new diagonals. Only elementary data structures are required by the algorithm. In particular, no dynamic search trees, of our algorithm.

Triangulating a simple polygon in linear time

Stephen J. Hartley Oxford University Press, New York, 1998, 260 pp. ISBN 0-19-511315-2, $45.00 Concurrent Programming  is a thorough treatment of Java multi-threaded programming for both a stand-alone and distributed environment. Designed mostly for students in concurrent or parallel programming classes, the text is also an excellent reference for the practicing professional developing multi-threaded programs or applets. Hartley first provides a complete explanation of the features of Java necessary to write concurrent programs, including topics such as exception handling, interfaces, and packages. He then gives the reader a solid background to write multi-threaded programs and also presents the problems introduced when writing concurrent programs—namely race conditions, mutual exclusion, and deadlock. Hartley also provides several software solutions that do not require the use of common process and thread mechanisms. Once the groundwork is laid for writing concurrent programs, Hartley then takes a different approach than most Java references. Rather than presenting how Java handles mutual exclusion with the  synchronized  keyword (although it is covered later), he first looks at semaphore-based solutions to classic concurrent problems such as bounded-buffer, readers-writers, and the dining philosophers. Hartley also uses the same approach to develop Java classes for monitors and message passing. This unique approach to introducing concurrency allows the readers to both understand how Java threads are synchronized and how the basic synchronization mechanism can be used to construct more abstract tools such as semaphores. If there is a shortcoming with the text it is with the lack of sufficient coverage of remote method invocation (RMI), although there is a section covering RMI. This is quite understandable as RMI is a fairly recent phenomenon with the Java community. Also, the classes that Hartley provides could easily implement RMI rather than sockets to handle communication. The strengths of the book include its ease in reading, several examples at the end of chapters, a package similar to Xtango that provides algorithm animation, and a supportive web site by the author (see  www.mcs.drexel.edu/~shartley/ConcProgJava/index.html ) including compressed source code. As Java becomes more dominant on the server side of multi-tier applications, writing thread-safe concurrent applications becomes even more important.  Concurrent Programming  is a strong step towards teaching students and professionals such skills. Greg Gagne, Westminster College of Salt Lake City Salt Lake City, Utah

Distributed Computing: Fundamentals, Simulations and Advanced Topics

https://www.princeton.edu/~yael/Publications/BotvinickNivBarto2008.pdf

Hierarchically organized behavior and its neural foundations: A reinforcement learning perspective

Biologically Inspired Approaches to Advanced Information Technology

A self-stabilizing distributed system is a fault-tolerant distributed system that tolerates any kind and any finite number of transient faults, such as message loss and memory corruption. In this paper, we formulate a concept of safe convergence in the framework of self-stabilization. An ordinary self-stabilizing algorithm has no safety guarantee while it is in converging from any initial configuration. The safe convergence property guarantees that a system quickly converges to a safe configuration, and then, it gracefully moves to an optimal configuration without breaking safety. Then, we propose a minimal independent dominating set algorithm with safe convergence property. Especially, the proposed algorithm computes the lexicographically first minimal independent dominating set according to the process identifier as a priority. The priority scheme can be arbitrarily changed such as stability, battery power and/or computation power of node.

/pdf/a-self-stabilizing-minimal-dominating-set-algorithm-with-5fcezzygb2.pdf

A self-stabilizing minimal dominating set algorithm with safe convergence

Self-stabilizing protocols can tolerate any type and any number of transient faults. However, in general, self-stabilizing protocols provide no guarantee about their behavior against permanent faults. This paper considers self-stabilizing link-coloring resilient to (permanent) Byzantine faults in arbitrary anonymous networks. First, we show that stabilizing link-coloring is impossible in anonymous cycles when there is no constraint on the spatial scheduling of processes. Then, given the assumption that no correct neighbors execute their actions simultaneously, we present a self-stabilizing link-coloring protocol that is also resilient to Byzantine faults in arbitrary anonymous networks. The protocol uses 2d-1 colors where d is the maximum degree in the network. This protocol guarantees that any link (u, v) between non faulty processes u and v is assigned a color within 2d+2 rounds and its color remains unchanged thereafter. Our protocol is Byzantine insensitive in the sense that the subsystem of correct processes remains operating properly in spite of unbounded Byzantine faults.

/pdf/stabilizing-link-coloration-of-arbitrary-networks-with-tzjm8nnqwx.pdf

Stabilizing Link-Coloration of Arbitrary Networks with Unbounded Byzantine Faults

This paper demonstrates the usefulness of distributed local verification of proofs, as a tool for the design of algorithms. In particular, it introduces a somewhat generalized notion of distributed local proofs, and utilizes it for improving the memory size complexity, while obtaining time efficiency too.As a result, we show that optimizing the memory size carries at most a small cost in terms of time, in the context of Minimum Spanning Tree (MST). That is, we present algorithms that are both time and space efficient for constructing an MST, for verifying it, and for detecting the location of the faults. This involves several steps that may be considered contributions in themselves.First, we generalize the notion of local proofs, trading off the locality (or, really, the time complexity) for memory efficiency. This adds a dimension to the study of distributed local proofs, that has been gaining attention recently.Second, as opposed to previous studies that presented only the labels verification part of a proof labeling schemes, we present here also a space and time efficient distributed self stabilizing marker algorithm to generates those labels. This presents proof labeling schemes as an algorithmic tool.Finally, we show how to enhance a known transformer that makes input/output algorithms self stabilizing. It now takes as input an efficient construction algorithm and an efficient self stabilizing proof labeling scheme, and produces an efficient self stabilizing algorithm.When used for MST, the transformer produces a memory optimal (i.e., O(log n) bits per node) self stabilizing algorithm, whose time complexity, namely, O(n), is significantly better even than that of previous algorithms that where not space optimal. (The time complexity of previous MST algorithms that used ©(log2n) memory bits per node was O(n2), and the time for optimal space algorithms was O(n|E|).)Our MST algorithm also has the important property that, if faults occur after the construction ended, then they are detected by some nodes within O(log2n) time in synchronous networks, or within O(? log2n) time in asynchronous ones. This property is inherited from the specific proof labeling scheme we construct. It answers an open problem posed by Awerbuch and Varghese (FOCS 1991). We also show that ©(log n) time is necessary if the memory size is restricted to O(log n) bits, even in synchronous networks.Another property is that if f faults occurred, then, within the required detection time above, they are detected by some node in the O(f log n) locality of each of the faults. We also show how to improve the above detection time and locality, at the expense of some increase in the memory.

/pdf/fast-and-compact-self-stabilizing-verification-computation-2wbqvjs09c.pdf

Fast and compact self stabilizing verification, computation, and fault detection of an MST

Self-stabilizing protocols can tolerate any type and any number of transient faults. But self-stabilizing protocols have no guarantee of their behavior against permanent faults. Thus, investigation concerning self-stabilizing protocols resilient to permanent faults is important.

This paper proposes a self-stabilizing link-coloring protocol resilient to (permanent) Byzantine faults in tree networks. The protocol assumes the central daemon, and uses Δ+1 colors where Δ is the maximum degree in the network. This protocol guarantees that, for any nonfaulty process v, if the distance from v to any Byzantine ancestor of v is greater than two, v reaches its desired states within three rounds and never changes its states after that. Thus, it achieves fault containment with radius of two. Moreover, we prove that the containment radius becomes Ω(log n) when we use only Δ colors, and prove that the containment radius becomes Ω(n) under the distributed daemon. These lower bound results prove necessity of Δ+1 colors and the central daemon to achieve fault containment with a constant radius.

Toshimitsu Masuzawa

Papers

Biologically Inspired Approaches to Advanced Information Technology

A self-stabilizing minimal dominating set algorithm with safe convergence

Stabilizing Link-Coloration of Arbitrary Networks with Unbounded Byzantine Faults

Fast and compact self stabilizing verification, computation, and fault detection of an MST

A self-stabilizing link-coloring protocol resilient to byzantine faults in tree networks