Piecemeal learning of an unknown environment
COLT '93 Proceedings of the sixth annual conference on Computational learning theory
Searching for a black hole in arbitrary networks: optimal mobile agent protocols
Proceedings of the twenty-first annual symposium on Principles of distributed computing
The power of a pebble: exploring and mapping directed graphs
Information and Computation
Optimal graph exploration without good maps
Theoretical Computer Science
Networks
Deterministic Rendezvous in Graphs
Algorithmica
Tree exploration with logarithmic memory
SODA '07 Proceedings of the eighteenth annual ACM-SIAM symposium on Discrete algorithms
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
Power-Aware collective tree exploration
ARCS'06 Proceedings of the 19th international conference on Architecture of Computing Systems
Exploring an unknown graph efficiently
ESA'05 Proceedings of the 13th annual European conference on Algorithms
Smart robot teams exploring sparse trees
MFCS'06 Proceedings of the 31st international conference on Mathematical Foundations of Computer Science
Distributed exploration of an unknown graph
SIROCCO'05 Proceedings of the 12th international conference on Structural Information and Communication Complexity
Online graph exploration: new results on old and new algorithms
ICALP'11 Proceedings of the 38th international conference on Automata, languages and programming - Volume Part II
Online multi-robot exploration of grid graphs with rectangular obstacles
Proceedings of the twenty-fourth annual ACM symposium on Parallelism in algorithms and architectures
Online exploration of all vertices in a simple polygon
FAW-AAIM'12 Proceedings of the 6th international Frontiers in Algorithmics, and Proceedings of the 8th international conference on Algorithmic Aspects in Information and Management
Online graph exploration: New results on old and new algorithms
Theoretical Computer Science
Fast collaborative graph exploration
ICALP'13 Proceedings of the 40th international conference on Automata, Languages, and Programming - Volume Part II
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A large group of autonomous, mobile entities e.g. robots initially placed at some arbitrary node of the graph has to jointly visit all nodes (not necessarily all edges) and finally return to the initial position. The graph is not known in advance (an online setting) and robots have to traverse an edge in order to discover new parts (edges) of the graph. The team can locally exchange information, using wireless communication devices. We compare a cost of the online and optimal offline algorithm which knows the graph beforehand (competitive ratio). If the cost is the total time of an exploration, we prove the lower bound of Ω(log k/ log log k) for competitive ratio of any deterministic algorithm (using global communication). This significantly improves the best known constant lower bound. For the cost being the maximal number of edges traversed by a robot (the energy) we present an improved (4- 2/k)-competitive online algorithm for trees.