Position discovery for a system of bouncing robots

International audienceA collection of n anonymous mobile robots is deployed on a unit-perimeter ring or a unit-length line segment. Every robot starts moving at constant speed, and bounces each time it meets any other robot or segment endpoint, changing its walk direction. We study the problem of position discovery, in which the task of each robot is to detect the presence and the initial positions of all other robots. The robots cannot communicate or perceive information about the environment in any way other than by bouncing nor they have control over their walks which are determined by their initial positions and their starting directions. Each robot has a clock allowing it to observe the times of its bounces. We give complete characterizations of all initial configurations for both the ring and the segment in which no position detection algorithm exists and we design optimal position detection algorithms for all feasible configurations

Information spreading by mobile particles on a line

A set of identical particles is deployed on an infinite line. Each particle moves freely on the line at arbitrary but constant speed. When two particles come into contact they bounce acquiring new velocities according to the law of mechanics for elastic collisions. Each particle initially holds a piece of information. The meeting particles automatically transmit to each other their entire currently possessed information (