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Groups Complexity Cryptology

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On the covering number of small symmetric groups and some sporadic simple groups

Luise-Charlotte Kappe
  • Department of Mathematical Sciences, State University of New York at Binghamton, Binghamton, NY 13902-6000, United States of America
  • Email:
/ Daniela Nikolova-Popova
  • Department of Mathematical Sciences, Florida Atlantic University, Boca Raton, FL 33431, United States of America
  • Email:
/ Eric SwartzORCID iD: http://orcid.org/0000-0002-1590-1595
Published Online: 2016-10-12 | DOI: https://doi.org/10.1515/gcc-2016-0010


A set of proper subgroups is a cover for a group if its union is the whole group. The minimal number of subgroups needed to cover G is called the covering number of G, denoted by σ(G). Determining σ(G) is an open problem for many nonsolvable groups. For symmetric groups Sn, Maróti determined σ(Sn) for odd n with the exception of n=9 and gave estimates for n even. In this paper we determine σ(Sn) for n=8,9,10,12. In addition we find the covering number for the Mathieu group M12 and improve an estimate given by Holmes for the Janko group J1.

Keywords: Symmetric groups; sporadic simple groups; finite union of proper subgroups; minimal number of subgroups

MSC 2010: 20D06; 20D60; 20D08; 20-04; 20F99


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About the article

Received: 2016-02-17

Published Online: 2016-10-12

Published in Print: 2016-11-01

Funding Source: Australian Research Council

Award identifier / Grant number: DP120101336

The third author acknowledges the support of the Australian Research Council Discovery Grant DP120101336 during his time spent at The University of Western Australia.

Citation Information: Groups Complexity Cryptology, ISSN (Online) 1869-6104, ISSN (Print) 1867-1144, DOI: https://doi.org/10.1515/gcc-2016-0010. Export Citation

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