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Presents the special issue in the journal "Parallel Processing Letters," which contains the best papers from the Centre Interantional de Rencontres Mathématiques workshopin October 2001. "Scheduling Issues in Survivality Applications Using Hybrid Fault Models," by A. W. Krings, W. S. Harrison, A. Azadmanesh and M. McQueen"; "Parallel Tabu Search Approaches for Two-Dimensional Cutting," by J. Blazewicz, A. Moret-Salvador and R. Walkowiak"; "Strategies for Workload Balancing in Cluster-Based Image Databases," by F. Drews, K. Ecker, O. Kao and S. Schomann.

In this paper, we focus on convergence packet routing techniques in an all-optical network, obtained from an Eulerian routing in the digraph modeling the target network. Given an Eulerian circuit C in a digraph C, we deal with the maximal number diamWC of arcs that a packet has to follow on C from its origin to its destination (we talk about the ending guarantee of the routing). We consider the Eulerian diameter of C as defined by E(C) = mm C ∈ Eul(G) diamWc, where E(G) is the set of all the Eulerian circuits in C. After giving a preliminary result about the complexity of finding ((C) for any digraph G, we give some lower and upper bounds of this parameter. The main part of the paper is devoted to the description of a combinatorial design of various network topologies having good Eulerian diameters. [ABSTRACT FROM AUTHOR]

We discuss nearest neighbor load balancing schemes on processor networks which are represented by a cartesian product of graphs and present a new optimal diffusion scheme for general graphs. In the first part of the paper, we introduce the Alternating-Direction load balancing scheme, which reduces the number of load balance iterations by a factor of 2 for cartesian products of graphs. The resulting flow is theoretically analyzed and can be very high for certain cases. Therefore, we further present the Mixed-Direction scheme which needs the same number of iterations but computes in most cases a much smaller flow. In the second part of the paper, we present a simple optimal diffusion scheme for general graphs, calculating a balancing flow which is minimal in the l2 norm. It is based on the spectra of the graph representing the network and needs only m — 1 iterations to balance the load with m being the number of distinct eigenvalues. Known optimal diffusion schemes have the same performance, however the optimal scheme presented in this paper can be implemented in a very simple manner. The number of iterations of optimal diffusion schemes is independent of the load scenario and, thus, they are practical for networks which represent graphs with known spectra. Finally, our experiments exhibit that the new optimal scheme can successfully be combined with the Alternating-Direction and Mixed-Direction schemes for efficient load balancing on product graphs. [ABSTRACT FROM AUTHOR]

Software systems can be modeled as complex networks in which software components are abstract nodes and their interactions are abstract edges. This paper attempts to characterize the structural quality of complex software networks. We propose to use a novel statistical measure, called average propagation ratio, to characterize the structural quality of general complex software networks, such as software adaptivity and maintainability. Several real-world complex software networks are analyzed in some depth to demonstrate the application of average propagation ratios. Furthermore, we investigate the key factors that determine the average propagation ratios of general complex software networks, resulting in a set of guiding principles that can be used in practical network design for improving the structural quality of complex software systems. [ABSTRACT FROM AUTHOR]

It is well known that a solution for the Firing Squad Synchronization Problem (FSSP) takes time 2n - 1, n being the number of soldiers. It is also known that a solution on a square of n × n soldiers takes the same time. The main result of this paper is a new solution for the FSSP on networks shaped as squares. Our solution is optimal in two aspects: it is communication optimal (the so-called 1-bit solution) and is also time optimal, as it takes 2n - 1 time. It is also used as a building block to construct a very efficient solution on the square torus. Our approach applies also to linearly shaped networks and yields on the ring almost optimal time & communication solutions. In particular, for the square torus with n rows and rings of n processors, if n is even our solution is time & communication optimal. Otherwise, it is communication-optimal but does not match the lower bound on the time of a synchronization just by 1 time unit. [ABSTRACT FROM AUTHOR]

Sense of direction is a property of the edge-labeling of a network whose availability facilitates computations and often decreases their complexity. In this paper we consider the problem of providing a sense of direction to an anonymous, unoriented torus. The edges of the torus are initially labeled arbitrarily, and they have to be relabeled with a classical compass sense of direction. We first describe an algorithm where the relabeling of the edges is performed by a mobile agent that carries a token. The algorithm is optimal both in terms of number of tokens (with no tokens the task cannot be performed), and in terms of number of moves. We then show that the same technique can be used to orient the torus in the classical message-passing environment, thus obtaining an orientation algorithm that improves all the existing ones in this setting. [ABSTRACT FROM AUTHOR]

This paper proposes an adaptive network architecture, which can emulate the human knowledge as the fuzzy logic rule, and its applications as the controller for nonlinear systems. The structure of this proposed network, multi-input Fuzzy Rule Emulated Network or FREN, is derived based on human knowledge in the form of fuzzy IF-THEN rules. The initial setting of its parameters can be intuitively chosen from expert's experience. During the learning phase based on the gradient search, the learning rate can be adapted itself to remain the stability with the Lyapunov method. The performance of our network is presented by using this network as controller for the single invert pendulum plant and the water bath temperature control system. The comparison results with other conventional control algorithms such as artificial neural networks and PID controllers can be illustrated in each example. [ABSTRACT FROM AUTHOR]

Multicasting protocols deliver data packets from a source node to multiple receivers, and serve a very important function in mobile ad-hoc networks (MANETs). In this paper, a novel receiver-initiated soft-state probabilistic multicasting protocol (RISP) for MANETs is proposed. RISP is inspired by the ant colony's route-seeking mechanism, in which an individual ant chooses the optimal path to its destination through cooperation with others in a totally distributed manner. Imitating the behaviour of ants in nature, RISP introduces probabilistic forwarding and soft-state for making relay decisions that are automatically adaptive to node mobility in MANETs. Compared with other protocols, we show by computer simulations that RISP has lower delivery redundancy, while achieving higher delivery ratio at all mobility scenarios. Furthermore, RISP has lower control overhead. [ABSTRACT FROM AUTHOR]

This research addresses scheduling issues in networked computer systems with survivability requirements, i.e. systems in which essential services must survive malicious acts. In order to achieve survivability based on spatial redundancy, agreement algorithms are needed as a mechanism to consolidate results of individual replicas. The potentially enormous overhead associated with communication and voting schemes of the algorithms put unique burdens on the scheduler as the efficiency of scheduling determines the suitability of the agreement algorithm. This paper derives agreement task graphs, representing computations, and inter-process communication based on phantom tasks. Task graph primitives are identified and it is shown how their scheduling directly influences the performance of the agreement algorithm. Finally, the notion of dynamic k-of-N precedence is introduced and its impact on resource reclaiming for early stopping algorithms is discussed. [ABSTRACT FROM AUTHOR]

In this paper we study the square grid area required for laying out H[sub l], the Boolean hypercube of N=2[sup l] vertices. It is shown that this area is [formula]. We describe a layout which occupies this much area and prove that no layout of less area exists. [ABSTRACT FROM AUTHOR]

In this paper, we consider the problem of constructing a multicast tree in star interconnection networks under the single-port communication model. Unlike previous schemes for constructing space-efficient multicast trees, we adopt the completion time of each multicast as the objective function to be minimized. In particular, we study a special case of the problem in which all destination vertices are immediate neighbors of the source vertex, and propose a multicast scheme of [formula] time units for the star graph of dimension n. [ABSTRACT FROM AUTHOR]