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[FORTHCOMING] Permutation groups with two orbits having constant movement

[FORTHCOMING] Groupe de permutations avec deux orbites à mouvement constant


Mehdi Rezaei
Buein Zahra Technical University
Iran

Mehdi Alaeiyan
Iran University of Science and Technology
Iran



Validated on 7 August 2024   DOI : TBA

Abstract

Résumé

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Mots-clés

Let G be a permutation group on a set Ω with no fixed points in Ω, and let m be a positive integer. If for each subset Γ of Ω the size ΓgΓ| is bounded, for gG, the movement of g is defined as move (g):=max over all subsets \Gamma of \Omega, and move (G) is defined as the maximum of move (g) over all non-identity elements of g\in G. Suppose that G is not a 2-group. It was shown by Praeger that |\Omega|\leqslant\lceil\frac{2mp}{p-1}\rceil+t-1, where t is the number of G-orbits on \Omega and p is the least odd prime dividing |G|. In this paper, we classify all permutation groups with maximum possible degree |\Omega|=\lceil\frac{2mp}{p-1}\rceil+t-1 for t=2, in which every non-identity element has constant movement m.

Let G be a permutation group on a set \Omega with no fixed points in \Omega, and let m be a positive integer. If for each subset \Gamma of \Omega the size \Gamma^{g}-\Gamma| is bounded, for g\in G, the movement of g is defined as move (g):=\max{|\Gamma^{g}-\Gamma|} over all subsets \Gamma of \Omega, and move (G) is defined as the maximum of move (g) over all non-identity elements of g\in G. Suppose that G is not a 2-group. It was shown by Praeger that |\Omega|\leqslant\lceil\frac{2mp}{p-1}\rceil+t-1, where t is the number of G-orbits on \Omega and p is the least odd prime dividing |G|. In this paper, we classify all permutation groups with maximum possible degree |\Omega|=\lceil\frac{2mp}{p-1}\rceil+t-1 for t=2, in which every non-identity element has constant movement m.

Intransitive permutation groups orbits bounded movement constant movement.

Intransitive permutation groups orbits bounded movement constant movement

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