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Noah Caplinger
Large totally symmetric sets
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Published: |
July 25, 2023. |
Keywords: |
Totally symmetric set, Symmetric Group, Automorphism. |
Subject [2020]: |
20F99. |
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Abstract
A totally symmetric set is a subset of a group such that every permutation of the subset can be realized by conjugation in the group. The (non-)existence of large totally symmetric sets obstruct homomorphisms, so bounds on the sizes of totally symmetric sets are of particular use. In this paper, we prove that if a group has a totally symmetric set of size k, it must have order at least (k+1)!. We also show that with three exceptions, {(1 i)| i = 2,...,n} ∈ Sn is the only totally symmetric set making this bound sharp, a fact which gives a new perspective on the automorphism group of Sn.
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Acknowledgements
The author would like to thank Dan Margalit and Dan Minahan for their suggestion to push Theorem 1.1 farther than a simple bound. He is also grateful to Dan Margalit and an anonymous referee for their helpful comments.
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Author information
Noah Caplinger
University of Chicago
Department of Mathematics
Eckhart Hall, 1118-32 E. 58th Street
Chicago, IL 60637, USA
ncaplinger@uchicago.edu
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