Based on the two-list algorithm and the parallel three-list algorithm, an improved parallel three-list algorithm for knapsack problem is proposed, in which the method of divide and conquer, and parallel merging withou...Based on the two-list algorithm and the parallel three-list algorithm, an improved parallel three-list algorithm for knapsack problem is proposed, in which the method of divide and conquer, and parallel merging without memory conflicts are adopted. To find a solution for the n-element knapsack problem, the proposed algorithm needs O（2^3n/8） time when O（2^3n/8） shared memory units and O（2^n/4） processors are available. The comparisons between the proposed algorithm and 10 existing algorithms show that the improved parallel three-fist algorithm is the first exclusive-read exclusive-write （EREW） parallel algorithm that can solve the knapsack instances in less than O（2^n/2） time when the available hardware resource is smaller than O（2^n/2） , and hence is an improved result over the past researches.展开更多
A conflict is an event in which two or more aircraft experience a loss of minimum separation. In this paper, we formulate the problem of solving conflicts arising among several aircraft moving in a shared airspace as ...A conflict is an event in which two or more aircraft experience a loss of minimum separation. In this paper, we formulate the problem of solving conflicts arising among several aircraft moving in a shared airspace as a Constraint Satisfaction Problem (CSP). The constraint satisfaction problem being NP-complete, the algorithms developed to solve it have been of two types: non-systematic and systematic search methods. In this paper, we have considered a breakout algorithm as an example of non-systematic search methods and a backtracking procedure that maintains Arc Consistency (MAC) as an example of systematic search methods. The performance of these algorithms was compared experimentally and the Breakout algorithm is shown to be clearly superior.展开更多
文摘Based on the two-list algorithm and the parallel three-list algorithm, an improved parallel three-list algorithm for knapsack problem is proposed, in which the method of divide and conquer, and parallel merging without memory conflicts are adopted. To find a solution for the n-element knapsack problem, the proposed algorithm needs O（2^3n/8） time when O（2^3n/8） shared memory units and O（2^n/4） processors are available. The comparisons between the proposed algorithm and 10 existing algorithms show that the improved parallel three-fist algorithm is the first exclusive-read exclusive-write （EREW） parallel algorithm that can solve the knapsack instances in less than O（2^n/2） time when the available hardware resource is smaller than O（2^n/2） , and hence is an improved result over the past researches.
文摘A conflict is an event in which two or more aircraft experience a loss of minimum separation. In this paper, we formulate the problem of solving conflicts arising among several aircraft moving in a shared airspace as a Constraint Satisfaction Problem (CSP). The constraint satisfaction problem being NP-complete, the algorithms developed to solve it have been of two types: non-systematic and systematic search methods. In this paper, we have considered a breakout algorithm as an example of non-systematic search methods and a backtracking procedure that maintains Arc Consistency (MAC) as an example of systematic search methods. The performance of these algorithms was compared experimentally and the Breakout algorithm is shown to be clearly superior.
