Cherlin's conjecture on finite primitive binary permutation groups

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Let GG be a permutation group on a set Ω\Omega. For a positive integer nn and tuples I=(ω1,…,ωn)I=(\omega_1,\ldots,\omega_n) and JJ in Ωn\Omega^n, write Ig=(ω1g,…,ωng)I^g=(\omega_1^g,\ldots,\omega_n^g) and let Iij=(ωi,ωj)I_{ij}=(\omega_i,\omega_j) denote the corresponding 2-subtuple. The group GG is binary if, for every positive integer nn and all I,J∈ΩnI,J\in\Omega^n, there exists g∈Gg\in G with Ig=JI^g=J if and only if, for every pair i<ji<j, there exists gij∈Gg_{ij}\in G with Iijgij=JijI_{ij}^{g_{ij}}=J_{ij}. A group is primitive if it acts transitively and preserves no nontrivial partition of Ω\Omega. An affine orthogonal group is a group V⋊O(V)V\rtimes \mathrm{O}(V) in which VV is a vector space over a finite field equipped with a non-degenerate anisotropic quadratic form, acting on itself by translations with complement the full orthogonal group O(V)\mathrm{O}(V). Cherlin's conjecture. A finite primitive binary permutation group must be one of the following: a symmetric group Sym⁡(n)\operatorname{Sym}(n) acting naturally on nn elements; a cyclic group of prime order acting regularly on itself; or an affine orthogonal group V⋊O(V)V\rtimes \mathrm{O}(V) of the specified type. The conjecture proposes a classification of finite primitive binary permutation groups. The terminology and the three families are discussed later in the paper; Cherlin proved the affine case, while the remaining cases were reduced to almost simple groups, so the general classification was still being completed in this work.

References

Primary source

Nick Gill, Martin W. Liebeck and Pablo Spiga, “Cherlin's conjecture on finite primitive binary permutation groups”, arXiv:2106.05154 (2021).

Additional references

2 papers in this index state this conjecture (2017–2021). The statement above is taken from the most recent of them; the others are arXiv:1705.05150.

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