We pose a new and intriguing question motivated by distributed computing regarding random walks on graphs: How long does it take for several independent random walks, starting from the same vertex, to cover an entire graph? We study the cover time - the expected time required to visit every node in a graph at least once - and we show that for a large collection of interesting graphs, running many random walks in parallel yields a speed-up in the cover time that is linear in the number of parallel walks. We demonstrate that an exponential speed-up is sometimes possible, but that some natural graphs allow only a logarithmic speed-up. A problem related to ours (in which the walks start from some probablistic distribution on vertices) was previously studied in the context of space efficient algorithms for undirected s - t -connectivity and our results yield, in certain cases, an improvement upon some of the earlier bounds.
%0 Conference Paper
%1 Alon2008Many
%A Alon, Noga
%A Avin, Chen
%A Koucky, Michal
%A Kozma, Gady
%A Lotker, Zvi
%A Tuttle, Mark R.
%B SPAA '08: Proceedings of the twentieth annual symposium on Parallelism in algorithms and architectures
%C New York, NY, USA
%D 2008
%I ACM
%K random\_walks networks information-diffusion
%P 119--128
%R 10.1145/1378533.1378557
%T Many random walks are faster than one
%U http://dx.doi.org/10.1145/1378533.1378557
%X We pose a new and intriguing question motivated by distributed computing regarding random walks on graphs: How long does it take for several independent random walks, starting from the same vertex, to cover an entire graph? We study the cover time - the expected time required to visit every node in a graph at least once - and we show that for a large collection of interesting graphs, running many random walks in parallel yields a speed-up in the cover time that is linear in the number of parallel walks. We demonstrate that an exponential speed-up is sometimes possible, but that some natural graphs allow only a logarithmic speed-up. A problem related to ours (in which the walks start from some probablistic distribution on vertices) was previously studied in the context of space efficient algorithms for undirected s - t -connectivity and our results yield, in certain cases, an improvement upon some of the earlier bounds.
%@ 978-1-59593-973-9
@inproceedings{Alon2008Many,
abstract = {{We pose a new and intriguing question motivated by distributed computing regarding random walks on graphs: How long does it take for several independent random walks, starting from the same vertex, to cover an entire graph? We study the cover time - the expected time required to visit every node in a graph at least once - and we show that for a large collection of interesting graphs, running many random walks in parallel yields a speed-up in the cover time that is linear in the number of parallel walks. We demonstrate that an exponential speed-up is sometimes possible, but that some natural graphs allow only a logarithmic speed-up. A problem related to ours (in which the walks start from some probablistic distribution on vertices) was previously studied in the context of space efficient algorithms for undirected s - t -connectivity and our results yield, in certain cases, an improvement upon some of the earlier bounds.}},
added-at = {2019-06-10T14:53:09.000+0200},
address = {New York, NY, USA},
author = {Alon, Noga and Avin, Chen and Koucky, Michal and Kozma, Gady and Lotker, Zvi and Tuttle, Mark R.},
biburl = {https://www.bibsonomy.org/bibtex/24ad3a6bd9f3faa9b7aa2262bd02dd3d7/nonancourt},
booktitle = {SPAA '08: Proceedings of the twentieth annual symposium on Parallelism in algorithms and architectures},
citeulike-article-id = {3768545},
citeulike-linkout-0 = {http://portal.acm.org/citation.cfm?id=1378533.1378557},
citeulike-linkout-1 = {http://dx.doi.org/10.1145/1378533.1378557},
doi = {10.1145/1378533.1378557},
interhash = {4391aa8e1c560db507a9fb1cc5c992b1},
intrahash = {4ad3a6bd9f3faa9b7aa2262bd02dd3d7},
isbn = {978-1-59593-973-9},
keywords = {random\_walks networks information-diffusion},
location = {Munich, Germany},
pages = {119--128},
posted-at = {2008-12-10 16:50:24},
priority = {3},
publisher = {ACM},
timestamp = {2019-07-31T12:36:13.000+0200},
title = {{Many random walks are faster than one}},
url = {http://dx.doi.org/10.1145/1378533.1378557},
year = 2008
}