Ralf Klasing

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We consider the problem of gathering identical, memoryless, mobile robots in one node of an anonymous unoriented ring. Robots start from different nodes of the ring. They operate in Look-Compute-Move cycles and have to end up in the same node. In one cycle, a robot takes a snapshot of the current configuration (Look), makes a decision to stay idle or to(More)
PREFACE Considerable attention in recent theoretical computer science is devoted to parallel computing. Here, we would like to present a special part of this large topic, namely, the part devoted to an abstract study of the dissemination of information in interconnection networks. The importance of this research area lies in the fact that the ability of a(More)
In this paper, we address the problem of gathering information in a central node of a radio network, where interference constraints are present. We take into account the fact that, when a node transmits, it produces interference in an area bigger than the area in which its message can actually be received. The network is modeled by a graph; a node is able(More)
In this paper we present a new heuristic called Adaptive Broadcast Consumption (ABC for short) for the Minimum-Energy Broadcast Routing (MEBR) problem. We first investigate the problem trying to understand which are the main properties not taken into account by the classic and well–studied MST and BIP heuristics, then we propose a new algorithm proving that(More)
In this paper we present new results on the performance of the Minimum Spanning Tree heuristic for the <i>Minimum-Energy Broadcast Routing</i> (MEBR) problem. We first prove that, for any number of dimensions <i>d</i> &#8805; 2, the approximation ratio of the heuristic does not increase when the power attenuation coefficient &#945;, that is the exponent to(More)
In this paper we define and study a call scheduling problem that is motivated by radio networks. In such networks the physical space is a common resource that nodes have to share, since concurrent transmissions cannot be interfering. We study how one can satisfy steady bandwidth demands according to this constraint. This leads to the definition of a call(More)
We consider the problem of exploring an anonymous undirected graph using an oblivious robot. The studied exploration strategies are designed so that the next edge in the robot’s walk is chosen using only local information, and so that some local equity (fairness) criterion is satisfied for the adjacent undirected edges. Such strategies can be seen as an(More)
The communication power of the one-way and two-way edge-disjoint path modes for broadcast and gossip is investigated. The complexity of communication algorithms is measured by the number of communication steps (rounds). The main results achieved are the following: 1. For each connected graph G n of n nodes, the complexity of broadcast in G n , B min (G n),(More)
Distributed Greedy Coloring is an interesting and intuitive variation of the standard Coloring problem. Given an order among the colors, a coloring is said to be greedy if there does not exist a vertex for which its associated color can be replaced by a color of lower position in the fixed order without violating the property that neighbouring vertices must(More)