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Open AccessProceedings ArticleDOI

Exploring unknown undirected graphs

TLDR
In this paper, the authors give an exploration algorithm whose penalty is O(|V(G)|) for every graph, and also show that some natural exploration algorithms cannot achieve this efficiency.
Abstract
A robot has to construct a complete map of an unknown environment modeled as an undirected connected graph. The task is to explore all nodes and edges of the graph using the minimum number of edge traversals. The penalty of an exploration algorithm running on a graph G = (V(G), E(G)) is the worst-case number of traversals in excess of the lower bound |E(G)| that it must perform in order to explore the entire graph. We give an exploration algorithm whose penalty is O(|V(G)|) for every graph. We also show that some natural exploration algorithms cannot achieve this efficiency.

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Citations
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Proceedings ArticleDOI

The power of a pebble: exploring and mapping directed graphs

TL;DR: A model that makes very limited assumptions about the environment is considered that can solve the mapping problem in this general setting and shows that if the robot knows an upper bound on the number of vertices then it can learn the graph efficiently with only one pebble.
Journal ArticleDOI

The Power of a Pebble

TL;DR: A model that makes very limited assumptions about the environment is considered, and it is shown that if the robot knows an upper bound on the number of vertices then it can learn the graph efficiently with only one pebble, and if it does not, then pebbles are both necessary and sufficient.
Journal ArticleDOI

Graph exploration by a finite automaton

TL;DR: It is shown that, for any K-state robot and any d ≥ 3, there exists a planar graph of maximum degree d with at most K + 1 nodes that the robot cannot explore, which improves all previous bounds in the literature.
Journal ArticleDOI

Exploring unknown undirected graphs

TL;DR: An exploration algorithm whose penalty is O(|V(G)|) for every graph is given and it is shown that some natural exploration algorithms cannot achieve this efficiency.
Journal ArticleDOI

Exploring an unknown graph

TL;DR: The main result is an algorithm that achieves a bounded ratio when the deficiency of the graph is unbounded, and two is achievable by a simple algorithm.
References
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Journal ArticleDOI

Shortest paths without a map

TL;DR: It is shown that the computational problem of devising a strategy that achieves a given worst-case ratio to the optimum path in a graph is a universal two-person game, and thus PSPACE-complete, whereas optimizing the expected ratio is #P-hard.
Proceedings ArticleDOI

Exploring an unknown graph

TL;DR: The main result is an algorithm that achieves a bounded ratio when the deficiency is bounded; unfortunately the ratio is exponential in the deficiency.
Journal ArticleDOI

How to learn an unknown environment. I: the rectilinear case

TL;DR: The problem faced by a robot that must explore and learn an unknown room with obstacles in it is considered and a competitive algorithm for the case of a polygonal room with a bounded number of obstacles is given.
Proceedings ArticleDOI

How to learn an unknown environment

TL;DR: The authors consider the problem faced by a newborn that must explore and learn an unknown room with obstacles in it and give a competitive algorithm for the case of a polygonal room with a bounded number of obstacles.
Proceedings ArticleDOI

Navigating in unfamiliar geometric terrain

TL;DR: This paper compares the distance walked by the robot in going from s to t to the length of the shortest path between s and t in the scene, and describes and analyze robot strategies that minimize this ratio for different kinds of scenes.