We present a THETA(n2) worst-case-time algorithm to determine the minimum finishing time for a preemptive schedule of n independent jobs on a hypercube of fixed dimension.
We present a THETA(n2) worst-case-time algorithm to determine the minimum finishing time for a preemptive schedule of n independent jobs on a hypercube of fixed dimension.
Given a large set of words W, we want to be able to determine quickly whether a query word q is close to any word in the set. A new data structure is presented that allows such queries to be answered very quickly even...
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Given a large set of words W, we want to be able to determine quickly whether a query word q is close to any word in the set. A new data structure is presented that allows such queries to be answered very quickly even for huge sets if the words are not too long and the query is quite close. The major application is in limiting password guessing by verifying, before a password is approved, that the password is not too close to a dictionary word. Other applications include spelling correction of bibliographic files and approximate matching.
Let G = (V, E) be a simple graph and k be a fixed positive integer. A vertex w is said to be a k-neighbourhood-cover of an edge (u, v) if d(u, w) less than or equal to k and d(v, w) less than or equal to k. A set C su...
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Let G = (V, E) be a simple graph and k be a fixed positive integer. A vertex w is said to be a k-neighbourhood-cover of an edge (u, v) if d(u, w) less than or equal to k and d(v, w) less than or equal to k. A set C subset of or equal to V is called a k-neighbourhood-covering set if every edge in E is k-neighbourhood-covered by some vertices of C. This problem is NP-complete for general graphs even it remains NP-complete for chordal graphs. Using dynamic programming technique, an O(n) time algorithm is designed to solve minimum 2-neighbourhood-covering problem on interval graphs. A data structure called interval tree is used to solve this problem.
With the rapid advances in communication and networking, especially in Grid technique, an increasing number of applications will involve computing systems. These applications in turn create an increasing demand for ef...
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With the rapid advances in communication and networking, especially in Grid technique, an increasing number of applications will involve computing systems. These applications in turn create an increasing demand for efficient resource management, request handling policies and access control. In this paper, we propose an efficient access control algorithm to protect the critical resource of server and improve the performance of the future grid communication computing system. Stability of CPU utilization is aimed to protect the server from overload and under-load. It is then beneficial to keep a satisfactory response time of requests, high throughput and less potential loss of service. We analyze the stability in detail and present a method for tuning control gains in order to guarantee the system stability. Finally, we perform simulations to evaluate the performance of the proposed algorithm. Simulation results demonstrate that the proposed algorithm stabilizes the utilization of CPU in the computing system if the control gains are appropriately chosen on the basis of system stability. It then achieves satisfactory performance.
The game-tree search algorithms AlphaBeta and SSS* illustrate 2 very different approaches to search in game trees. The recursive, depth-first AlphaBeta needs little memory, is simple to implement, is fast, and is dir...
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The game-tree search algorithms AlphaBeta and SSS* illustrate 2 very different approaches to search in game trees. The recursive, depth-first AlphaBeta needs little memory, is simple to implement, is fast, and is directional. SSS*, on the other hand, is best-first, iterative, and non-directional. The pruning power of SSS* is greater than that of AlphaBeta, but it requires a large amount of memory for its OPEN list and runs much slower than AlphaBeta. An alternative formulation of SSS* that also uses a global OPEN list, but succeeds in reducing the overhead substantially is called RecSSS*, which is a recursive implementation. RecSSS* readily generalizes to a procedure called GenGame, which yields AlphaBeta as a special case. This demonstrates that the gap between SSS* and AlphaBeta is not as wide as generally believed and that there exists a unified recursive scheme that subsumes the major game-tree search procedures. GenGame also gives rise to some interesting new algorithms such as QuickGame and MGame that employ a mix of best-first and depth-first search strategies and are intermediate between AlphaBeta and SSS* in pruning power and storage requirements.
The maximum weight k-independent set problem has applications in many practical problems like k-machines job scheduling problem, k-colourable subgraph problem, VLSI design layout and routing problem. Based on DAG (Dir...
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The maximum weight k-independent set problem has applications in many practical problems like k-machines job scheduling problem, k-colourable subgraph problem, VLSI design layout and routing problem. Based on DAG (Directed Acyclic Graph) approach, an O (kn(2)) time sequential algorithm is designed in this paper to solve the maximum weight k-independent set problem on weighted trapezoid graphs. The weights considered here are all non-negative and associated with each of the n vertices of the graph.
Let A be a Las Vegas algorithm, i.e., A is a randomized algorithm that always produces the correct answer when it stops but whose running time is a random variable. We consider the problem of minimizing the expected t...
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Let A be a Las Vegas algorithm, i.e., A is a randomized algorithm that always produces the correct answer when it stops but whose running time is a random variable. We consider the problem of minimizing the expected time required to obtain an answer from A using strategies which simulate A as follows: run A for a fixed amount of time t1, then run A independently for a fixed amount of time t2, etc. The simulation stops if A completes its execution during any of the runs. Let J = (t1, t2, . . .) be a strategy, and let l(A) = inf(J)T(A, J), where T(A, J) is the expected value of the running time of the simulation of A under strategy J. We describe a simple universal strategy J(univ), with the property that, for any algorithm A, T(A, J(univ)) = O(l(A) log(l(A))). Furthermore, we show that this is the best performance that can be achieved, up to a constant factor, by any universal strategy.
This paper considers the problem of computing a maximal independent set in a hypergraph. We present an efficient deterministic NC algorithm for finding a maximal independent set in a hypergraph of dimension 3: the alg...
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This paper considers the problem of computing a maximal independent set in a hypergraph. We present an efficient deterministic NC algorithm for finding a maximal independent set in a hypergraph of dimension 3: the algorithm runs in time O(log4n) time on n + m processors of an EREW PRAM and is optimal up to a polylogarithmic factor. Our algorithm adapts the technique of Goldberg and Spencer for finding a maximal independent set in a graph (or hypergraph of dimension 2). It is the first NC algorithm for finding a maximal independent set in a hypergraph of dimension greater than 2.
We present a technique for approximately maximizing a class of concave functions whose evaluation is NP complete. We assume that there is a polynomial-time approximation algorithm for evaluating a function and use it ...
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We present a technique for approximately maximizing a class of concave functions whose evaluation is NP complete. We assume that there is a polynomial-time approximation algorithm for evaluating a function and use it to design a polynomial-time algorithm for approximating the maximum of the function. Finding the exact maximum is NP complete. Our technique is based on Megiddo's parametric searching technique.
This paper presents an algorithm that determines whether an undirected graph has any holes of size at least k in O(n(k-3)M), where M is the time required to multiply two n by n matrices.
This paper presents an algorithm that determines whether an undirected graph has any holes of size at least k in O(n(k-3)M), where M is the time required to multiply two n by n matrices.
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