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dc.contributor.authorBailey, R. A.
dc.contributor.authorCameron, Peter J.
dc.contributor.authorKinyon, Michael
dc.contributor.authorPraeger, Cheryl
dc.identifier.citationBailey , R A , Cameron , P J , Kinyon , M & Praeger , C 2022 , ' Diagonal groups and arcs over groups ' , Designs, Codes and Cryptography , vol. 90 , no. 9 , pp. 2069-2080 .
dc.identifier.otherORCID: /0000-0003-3130-9505/work/96817528
dc.identifier.otherORCID: /0000-0002-8990-2099/work/96817531
dc.descriptionPartially supported by Simons Foundation Collaboration Grant 359872 and by Fundacaopara a Ciencia e a Tecnologia (Portuguese Foundation for Science and Technology) grant PTDC/MAT-PUR/31174/2017. Australian Research Council Discovery Grant DP160102323.en
dc.description.abstractIn an earlier paper by three of the present authors and Csaba Schneider, it was shown that, for m≥2, a set of m+1 partitions of a set Ω, any m of which are the minimal non-trivial elements of a Cartesian lattice, either form a Latin square (if m=2), or generate a join-semilattice of dimension m associated with a diagonal group over a base group G. In this paper we investigate what happens if we have m+r partitions with r≥2, any m of which are minimal elements of a Cartesian lattice. If m=2, this is just a set of mutually orthogonal Latin squares. We consider the case where all these squares are isotopic to Cayley tables of groups, and give an example to show the groups need not be all isomorphic. For m>2, things are more restricted. Any m+1 of the partitions generate a join-semilattice admitting a diagonal group over a group G. It may be that the groups are all isomorphic, though we cannot prove this. Under an extra hypothesis, we show that G must be abelian and must have three fixed-point-free automorphisms whose product is the identity. (We describe explicitly all abelian groups having such automorphisms.) Under this hypothesis, the structure gives an orthogonal array, and conversely in some cases. If the group is cyclic of prime order p, then the structure corresponds exactly to an arc of cardinality m+r in the (m−1)-dimensional projective space over the field with p elements, so all known results about arcs are applicable. More generally, arcs over a finite field of order q give examples where G is the elementary abelian group of order q. These examples can be lifted to non-elementary abelian groups using p-adic techniques.
dc.relation.ispartofDesigns, Codes and Cryptographyen
dc.subjectDiagonal groupen
dc.subjectOrthogonal arrayen
dc.subjectDiagonal semilatticeen
dc.subjectFrobenius groupen
dc.subjectQA Mathematicsen
dc.titleDiagonal groups and arcs over groupsen
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews. Centre for Interdisciplinary Research in Computational Algebraen
dc.contributor.institutionUniversity of St Andrews. Statisticsen
dc.contributor.institutionUniversity of St Andrews. Pure Mathematicsen
dc.description.statusPeer revieweden

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