Theoretical Computer Science
SODA selected papers from the third annual ACM-SIAM symposium on Discrete algorithms
Frontier-based exploration using multiple robots
AGENTS '98 Proceedings of the second international conference on Autonomous agents
Randomized robot navigation algorithms
Proceedings of the seventh annual ACM-SIAM symposium on Discrete algorithms
Exploring unknown environments with obstacles
Proceedings of the tenth annual ACM-SIAM symposium on Discrete algorithms
Exploring Unknown Environments
SIAM Journal on Computing
The power of a pebble: exploring and mapping directed graphs
Information and Computation
Optimal graph exploration without good maps
Theoretical Computer Science
Networks
Probabilistic computations: Toward a unified measure of complexity
SFCS '77 Proceedings of the 18th Annual Symposium on Foundations of Computer Science
SFCS '90 Proceedings of the 31st Annual Symposium on Foundations of Computer Science
The power of team exploration: two robots can learn unlabeled directed graphs
SFCS '94 Proceedings of the 35th Annual Symposium on Foundations of Computer Science
SIROCCO'07 Proceedings of the 14th international conference on Structural information and communication complexity
Exploring an unknown graph efficiently
ESA'05 Proceedings of the 13th annual European conference on Algorithms
Fast collaborative graph exploration
ICALP'13 Proceedings of the 40th international conference on Automata, Languages, and Programming - Volume Part II
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We consider the multi-robot exploration problem of an unknown n x n grid graph with oriented disjoint rectangular obstacles. All robots start at a given node and have to visit all nodes of the graph. The robots are unrestricted in their computational power and storage. In the local communication model the robots can exchange any information if they meet at the same node. In the global communication model all robots share the same knowledge. In this paper we present the first nontrivial upper and lower bounds. We show that k robots can explore the graph using only local communication in time O( n log2(n) + (f log n)/k), where f is the number of free nodes in the graph. This establishes a competitive upper bound of O(log2 n). For the lower bound we show a competitive factor of Ω((log k)/(log log k)) for deterministic exploration and Ω(√(log k)/(log log k)) for randomized exploration strategies using global communication.