Parallel Graph Algorithms Based Upon Broadcast Communications

In this paper, we shall show some common guidelines which we can use to design parallel algorithms under the single-channel broadcast communication model. We use several graph problems as a vehicle. The graph problems we solve include topological ordering, the connected component problem, breadth-first search, and depth-first search. If an ideal conflict resolution scheme is used, all of our algorithms require O(n) time by using n processors. Under such a situation, Manuscript received August 15, 1987; revised February 12, 1990. This work was supported in part by the National Science Council of the Republic of China under Contract NSC77-0408-E007-04. C.-B. Yang and W.-T. Chen are with the Institute of Computer Science, National Tsing Hua University, Hsinchu 30043, Taiwan, Republic of China. R. C. T. Lee is with the National Tsing Hua University, Hsinchu, and the Academia Sinica, Taipei, Taiwan, Republic of China. IEEE Log Number 9035959. our algorithms are all optimal. If a realistic conflict resolution is used, our algorithms require O(n log n) time by using n /log n processors. For both cases, all of our algorithms achieve optimal speedups.