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We show that the perfect matching problem in general graphs is in Quasi-NC. That is, we give a deterministic parallel algorithm which runs in O(\log^3 n) time on n^{O(\log^2 n)} processors. The result is obtained by a derandomization of the Isolation Lemma for perfect matchings, which was introduced in the classic paper by Mulmuley, Vazirani and Vazirani [1987] to obtain a Randomized NC algorithm...
The (s+t+1)-dimensional exchanged crossed cube (ECQ(s, t) for short), combines the advantage of the exchanged hypercube and the crossed cube. The Hamiltonicity connectivity is an important property in interconnection networks. In this paper, firstly, we prove that there exists not only a Hamiltonian path but also less than 1 than Hamiltonian path between any two distinct vertices in ECQ(s, t), where...
We discuss a parallel Lepp-bisection algorithm for two-dimensional mesh refinement over distributed memory systems. We discuss the subdivision of the mesh and the management of interface refinement and communication. We also study the empirical algorithm behavior.
The dimensions of twisted cubes in the original definition of twisted cubes are only limited to odd integers. In this paper, we first extend the dimensions of twisted cubes to all the positive integers. Then, we introduce the concept of the set of restricted faulty nodes into twisted cubes. We further prove that under the condition that each node of the n-dimensional twisted cube TQn has at least...
The aim of this paper is to show that a kind of boundary value problem for second-order ordinary differential equations which reduces to the problem of solving tridiagonal systems of linear equations can be efficiently solved on modern multicore computer architectures. A new method for solving such tridiagonal systems of linear equations, based on recently developed algorithms for solving linear recurrence...
In this paper we present a low cost fault-tolerant attitude determination system to a scientific satellite using COTS devices. We related our experience in developing the attitude determination system, where we combine proven fault tolerance techniques to protect the whole system composed only by COTS from the effects produced by transient faults. We detailed the failure cases and the detection, reconfiguration...
Complex motion makes consecutive frames experience dramatic change, and thus becomes a barrier to object-tracking. Three factors contribute to more complexity of motion: longer sampling period,an moving object with complex appearance and nonrestraint movement, occlusion, which causes mean shift algorithm losing its target due to too low a Bhattacharyya coefficient. To treat it, mean shift algorithm...
We describe a benchmark of publicly-available multi-threaded programs with documented bugs in them. This project was initiated a few years ago with the goal of helping research groups in the fields of concurrent testing and debugging to develop tools and algorithms that improve the quality of concurrent programs. We present a survey of usage of the benchmark, concluding that the benchmark had an impact...
The Boolean Satisfiability Problem or SAT is one of the most important problems in computer science. Nowadays, there are different types of algorithms to solve instances with thousands of variables, and much research is being carried out looking for more efficient algorithms to solve larger and harder instances. This work proposes the utilization of a Team Algorithm (TA) strategy combining different...
A principal factor in sensor network design is energy efficiency. In this work, we propose to extend the lifetime of sensor networks using appropriate choice of sensor node distribution. The key idea of our scheme is to deploy more nodes in areas of extensive energy usage. Using this scheme of sensor node distribution, we use probabilistic angular routing to route data packets from the sensor nodes...
It is becoming increasingly difficult to implement effective systems for preventing network attacks, due to the combination of (1) the rising sophistication of attacks requiring more complex analysis to detect, (2) the relentless growth in the volume of network traffic that we must analyze, and, critically, (3) the failure in recent years for uniprocessor performance to sustain the exponential gains...
A new parallel algorithm for the maximal independent set problem (MIS) is constructed. It runs in O(log4 n) time when implemented on a linear number of EREW-processors. This is the first deterministic algorithm for MIS whose running time is polylogarithmic and whose processor-time product is optimal up to a polylogarithmic factor.
We introduce a new primitive, the Resource Controller, which abstracts the problem of controlling the total amount of resources consumed by a distributed algorithm. We present an efficient distributed algorithm to implement this abstraction. The message complexity of our algorithm per participating node is polylogarithmic in the size of the network, compared to the linear cost per node of the naive...
An algorithm is given for the multi-writer version of the Concurrent Reading While Writing (CRWW) problem. The algorithm solves the problem of allowing simultaneous access to arbitrarily sized shared data without requiring waiting, and hence avoids mutual exclusion. This. demonstrates that a quite complicated concurrent control problem can be solved-without eliminating the efficiency of parallelism...
In practice, the average time of (deterministic or randomized) sorting algorithms seems to be more relevant than the worst case time of deterministic algorithms. Still, the many known complexity bounds for parallel comparison sorting include no nontrivial lower bounds for the average time required to sort by comparisons n elements with p processors (via deterministic or randomized algorithms). We...
This paper addresses the problem of how to adapt an algorithm designed for fixed topology networks to produce the intended results, when run in a network whose topology changes dynamically, in spite of encountering topological changes during its execution. We present a simple and unified procedure, called a reset procedure, which, when combined with the static algorithm, achieves this adaptation....
It is shown that the problem of deciding and constructing a perfect matching in bipartite graphs G with the polynomial permanents of their n × n adjacency matrices A (perm(A) = nO(1)) are in the deterministic classes NC2 and NC3, respectively. We further design an NC3 algorithm for the problem of constructing all perfect matchings (enumeration problem) in a graph G with a permanent bounded by O(nk)...
We present a randomized parallel algorithm for finding a simple cycle separator in a planar graph. The size of the separator is O(√n) and it separates the graph so that the largest part contains at most 2/8 ?? n vertices. Our algorithm takes T = O(log2(n)) time and P = O(n + f1+ε) processors, where n is the number of vertices, f is the number of faces and ε is any positive constant. The algorithm...
This paper considers mesh computers with buses, where each bus provides a broadcasting capability to the processors connected to it. We first disprove a published claim by showing that on a 2-dimensional mesh with a bus for each row, where each row must solve its own problem with data that is independent of all other rows, there are problems where the rows can cooperatively solve all subproblems faster...
The deadlock resolution problem can be informally stated as follows. There exists a set of actions, generated at different times, with some complex and contradictory precedence constraints between their executions. To resolve a deadlock, some of the actions need to be aborted; this enables to execute the remaining ones. This problem naturally arises in the context of distributed systems, e.g. communication...
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