Please use this identifier to cite or link to this item: http://hdl.handle.net/2381/32123
Title: On Temporal Graph Exploration
Authors: Erlebach, Thomas
Hoffmann, Michael
Kammer, F.
First Published: 20-Jun-2015
Presented at: ICALP, Kyoto
Start Date: 6-Jul-2015
End Date: 10-Jul-2015
Publisher: Springer Berlin Heidelberg
Citation: Proceedings of the 42nd International Colloquium on Automata, Languages, and Programming, Lecture Notes in Computer Science Volume 9134, 2015, pp. 444-455 (12)
Abstract: A temporal graph is a graph in which the edge set can change from step to step. The temporal graph exploration problem TEXP is the problem of computing a foremost exploration schedule for a temporal graph, i.e., a temporal walk that starts at a given start node, visits all nodes of the graph, and has the smallest arrival time. We consider only temporal graphs that are connected at each step. For such temporal graphs with $n$ nodes, we show that it is $\NP$-hard to approximate TEXP with ratio $O(n^{1-\epsilon})$ for any $\epsilon>0$. We also provide an explicit construction of temporal graphs that require $\Theta(n^2)$ steps to be explored. We then consider TEXP under the assumption that the underlying graph (i.e. the graph that contains all edges that are present in the temporal graph in at least one step) belongs to a specific class of graphs. Among other results, we show that temporal graphs can be explored in $O(n^{1.5}k^2\log n)$ steps if the underlying graph has treewidth $k$ and in $O(n\log^3 n)$ steps if the underlying graph is a $2\times n$ grid. Finally, we show that sparse temporal graphs with regularly present edges can always be explored in $O(n)$ steps.
DOI Link: 10.1007/978-3-662-47672-7_36
ISSN: 0302-9743
ISBN: 978-3-662-47671-0
Links: http://hdl.handle.net/2381/32123
http://link.springer.com/chapter/10.1007/978-3-662-47672-7_36
Version: Post-print
Status: Peer-reviewed
Type: Conference Paper
Rights: The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-662-47672-7_36
Appears in Collections:Conference Papers & Presentations, Dept. of Computer Science

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