Approximation algorithms for information dissemination problems

Broadcasting and gossiping are basic tools for high performance programming on parallel and distributed systems. Unfortunately, they are known to be NP-hard problems. This paper deals with approximation algorithms for broadcasting and gossiping. We consider both round-complexity and step-complexity in the telephone model. After an overview of previously derived approximation algorithms, we present new strategies for broadcasting and gossiping in any networks. Broadcasting strategies are based on the construction of edge-disjoint spanning trees. Gossiping strategies are based on on-line computation of matchings along with the gossiping process. Our approximation algorithms for broadcasting offer almost optimal complexity when the number of messages to be broadcasted is large. We show that our best approximation algorithm for gossiping performs optimally in many cases. We also show experimentally that it performs faster than the best known handmade algorithms in some particular cases.