A new notion of transitivity for groups and sets of permutations

dc.creatorMartin, William J.
dc.creatorSagan, Bruce E.
dc.date2002-06-17
dc.date.accessioned2026-07-07T04:49:09Z
dc.date.available2026-07-07T04:49:09Z
dc.descriptionLet $Ω=\{1,2,...,n\}$ where $n \ge 2$. The {\em shape} of an ordered set partition $P=(P_1,..., P_k)$ of $Ω$ is the integer partition $λ=(λ_1,...,λ_k)$ defined by $λ_i = |P_i|$. Let G be a group of permutations acting on $Ω$. For a fixed partition $λ$ of n, we say that G is {\em $λ$-transitive} if G has only one orbit when acting on partitions P of shape $\la$. A corresponding definition can also be given when G is just a set. For example, if $λ=(n-t,1,...,1)$, then a $λ$-transitive group is the same as a t-transitive permutation group and if $λ=(n-t,t)$, then we recover the t-homogeneous permutation groups. In this paper, we use the character theory of the symmetric group $S_n$ to establish some structural results regarding $λ$-transitive groups and sets. In particular, we are able to generalize a theorem of Livingstone and Wagner about t-homogeneous groups. We survey the relevant examples coming from groups. While it is known that a finite group of permutations can be at most 5-transitive unless it contains the alternating group, we show that it is possible to construct a non-trivial t-transitive set of permutations for each positive integer t. We also show how these ideas lead to a split basis for the association scheme of the symmetric group.
dc.description13 pages
dc.identifierhttps://arxiv.org/abs/math/0206163
dc.identifierhttp://arxiv.org/abs/math/0206163
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/64317
dc.subjectGroup Theory
dc.subjectCombinatorics
dc.subject20B20 (Primary) 20C30, 05E10, 05E30 (Secondary)
dc.titleA new notion of transitivity for groups and sets of permutations
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