Ring Exploration by Oblivious Robots with Vision Limited to 2 or 3

The problem of exploring a finite discrete space by autonomous mobile robots is a basic building block for many applications. Space to explore is partitioned into a finite number of locations represented by a graph, where nodes represent indivisible locations that can be sensed by the robots, and where edges represent the possibility for a robot to move from one location to the other. %, e.g., a building, a town, a factory, or a mine. We address the terminating exploration problem which requires that starting from a configuration where no two robots occupy the same node, every node needs to be visited by at least one robot, with the additional constraint that all robots eventually stop moving.