1,446 research outputs found
Message and time efficient multi-broadcast schemes
We consider message and time efficient broadcasting and multi-broadcasting in
wireless ad-hoc networks, where a subset of nodes, each with a unique rumor,
wish to broadcast their rumors to all destinations while minimizing the total
number of transmissions and total time until all rumors arrive to their
destination. Under centralized settings, we introduce a novel approximation
algorithm that provides almost optimal results with respect to the number of
transmissions and total time, separately. Later on, we show how to efficiently
implement this algorithm under distributed settings, where the nodes have only
local information about their surroundings. In addition, we show multiple
approximation techniques based on the network collision detection capabilities
and explain how to calibrate the algorithms' parameters to produce optimal
results for time and messages.Comment: In Proceedings FOMC 2013, arXiv:1310.459
Analysis of the Error Propagation Phenomenon in Network Structures
The analysis of error propagation is of fundamental importance to assure safe operation and management of abnormal situations in any distributed information system. In this paper, the quantitative and qualitative methods are proposed to analyze possible error propagation scenarios based on different topologies, error types and probability distributions. The most interesting from our point of view is the course of error propagation in simple structures that are contained in more complex ones. These complex structures, which have attracted the attention of scientists for many decades, are traditionally analyzed with the use of formalisms from graph theory. Certain types of graphs are often used to model naturally occurring complex structures, such as social networks. Graph-theoretic approach proved successful when applied to social networks and other naturally occurring complex networks. The research was verified based on the experiments conducted on simulation model. The results provide some ideas of robustness -- the knowledge how to design the most error resistant architectures in complex environments
Topological Properties and Broadcasting Algorithmsof the Generalized-Star Cubeă
AbstractâIn this research, another version of the star cube called the generalized-star cube, GSC(n, k, m), is presented as a three level interconnection topology. GSC(n, k, m) is a product graph of the (n, k)-star graph and the m-dimensional hypercube (m-cube). It can be constructed in one of two ways: to replace each node in an m-cube with an (n, k)-star graph, or to replace each node in an (n, k)-star graph with an m-cube. Because there are three parameters m, n, and k, the network size of GSC(n, k, m) can be changed more ïŹexibly than the star graph, star-cube, and (n, k)-star graph. We ïŹrst investigate the topological properties of the GSC(n, k, m), such as the node degree, diameter, average distance, and cost. Also, the regularity and node symmetry of the GSC(n, k, m) are derived.Then, we illustrate the broadcasting algorithms for both of the single-port and all-port models. To develop these algorithms, we use the spanning binomial tree, the neighbourhood broadcasting algorithm, and the minimum dominating set. The complexities of the broadcasting algorithms are also examined
Hybrid Dissemination: Adding Determinism to Probabilistic Multicasting in Large-Scale P2P Systems
Abstract. Epidemic protocols have demonstrated remarkable scalability and robustness in disseminating information on internet-scale, dynamic P2P systems. However, popular instances of such protocols suffer from a number of significant drawbacks, such as increased message overhead in push-based systems, or low dissemination speed in pull-based ones. In this paper we study push-based epidemic dissemination algorithms, in terms of hit ratio, communication overhead, dissemination speed, and resilience to failures and node churn. We devise a hybrid push-based dissemination algorithm, combining probabilistic with deterministic properties, which limits message overhead to an order of magnitude lower than that of the purely probabilistic dissemination model, while retaining strong probabilistic guarantees for complete dissemination of messages. Our extensive experimentation shows that our proposed algorithm outperforms that model both in static and dynamic network scenarios, as well as in the face of large-scale catastrophic failures. Moreover, the proposed algorithm distributes the dissemination load uniformly on all participating nodes. Keywords: Epidemic/Gossip protocols, Information Dissemination, Peer-to-Peer
Properties and algorithms of the (n, k)-star graphs
The (n, k)-star interconnection network was proposed in 1995 as an attractive alternative
to the n-star topology in parallel computation. The (n, k )-star has significant
advantages over the n-star which itself was proposed as an attractive alternative to
the popular hypercube. The major advantage of the (n, k )-star network is its scalability,
which makes it more flexible than the n-star as an interconnection network. In
this thesis, we will focus on finding graph theoretical properties of the (n, k )-star as
well as developing parallel algorithms that run on this network.
The basic topological properties of the (n, k )-star are first studied. These are
useful since they can be used to develop efficient algorithms on this network. We then
study the (n, k )-star network from algorithmic point of view. Specifically, we will
investigate both fundamental and application algorithms for basic communication,
prefix computation, and sorting, etc.
A literature review of the state-of-the-art in relation to the (n, k )-star network as
well as some open problems in this area are also provided
Properties and algorithms of the hyper-star graph and its related graphs
The hyper-star interconnection network was proposed in 2002 to overcome the
drawbacks of the hypercube and its variations concerning the network cost, which is
defined by the product of the degree and the diameter. Some properties of the graph
such as connectivity, symmetry properties, embedding properties have been studied
by other researchers, routing and broadcasting algorithms have also been designed.
This thesis studies the hyper-star graph from both the topological and algorithmic
point of view. For the topological properties, we try to establish relationships between
hyper-star graphs with other known graphs. We also give a formal equation for the
surface area of the graph. Another topological property we are interested in is the
Hamiltonicity problem of this graph.
For the algorithms, we design an all-port broadcasting algorithm and a single-port
neighbourhood broadcasting algorithm for the regular form of the hyper-star graphs.
These algorithms are both optimal time-wise.
Furthermore, we prove that the folded hyper-star, a variation of the hyper-star, to be
maixmally fault-tolerant
Properties and algorithms of the (n, k)-arrangement graphs
The (n, k)-arrangement interconnection topology was first introduced in 1992. The
(n, k )-arrangement graph is a class of generalized star graphs. Compared with the
well known n-star, the (n, k )-arrangement graph is more flexible in degree and diameter.
However, there are few algorithms designed for the (n, k)-arrangement graph
up to present. In this thesis, we will focus on finding graph theoretical properties
of the (n, k)- arrangement graph and developing parallel algorithms that run on this
network.
The topological properties of the arrangement graph are first studied. They include
the cyclic properties. We then study the problems of communication: broadcasting
and routing. Embedding problems are also studied later on. These are very
useful to develop efficient algorithms on this network.
We then study the (n, k )-arrangement network from the algorithmic point of view.
Specifically, we will investigate both fundamental and application algorithms such as
prefix sums computation, sorting, merging and basic geometry computation: finding
convex hull on the (n, k )-arrangement graph.
A literature review of the state-of-the-art in relation to the (n, k)-arrangement
network is also provided, as well as some open problems in this area
Network models of innovation and knowledge diffusion
Much of modern micro-economics is built from the starting point of the perfectly competitive market. In this model there are an infinite number of agents â buyers and sellers, none of whom has the power to influence the price by his actions. The good is well-defined, indeed it is perfectly standardized. And any interactions agents have is mediated by the market. That is, all transactions are anonymous, in the sense that the identities of buyer and seller are unimportant. Effectively, the seller sells âto the marketâ and the buyer buys âfrom the marketâ. This follows from the standardization of the good, and the fact that the market imposes a very strong discipline on prices. Implicit here is one (or both) of two assumptions. Either all agents are identical in every relevant respect, apart, possibly, from the prices they ask or offer; or every agent knows every relevant detail about every other agent. If the former, then obviously my only concern as a buyer is the prices asked by the population of sellers since in every other way they are identical. If the latter, then each seller has a unique good, and again what I am concerned with is the price of it. In either case, we see that prices capture all relevant information and are enough for every agent to make all the decisions he needs to make....economics of technology ;
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