Browsing Morris, Joy by Title

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  • On colour-preserving automorphisms of Caley graphs 
    Hujdurovic, Ademir; Kutnar, Klavdija; Morris, Dave Witte; Morris, Joy (Drustvo Matematikov, Fizikov in AstronomovArts and ScienceDepartment of Mathematics and Computer ScienceUniversity of PrimorskaUniversity of Lethbridge, 2016)
    We study the automorphisms of a Cayley graph that preserve its natural edge-colouring. More precisely, we are interested in groups G, such that every such automorphism of every connected Cayley graph on G has a very simple ...
  • On the automorphism groups of almost all circulant graphs and digraphs 
    Bhoumik, Soumya; Dobson, Edward; Morris, Joy (Drustvo Matematikov, Fizikov in AstronomovArts and ScienceDepartment of Mathematics and Computer ScienceFort Hays State UniversityMississippi State UniversityUniversity of PrimorskaUniversity of Lethbridge, 2018)
    We attempt to determine the structure of the automorphism group of a generic circulant graph. We first show that almost all circulant graphs have automorphism groups as small as possible. The second author has conjectured ...
  • Semiregular automorphisms of cubic vertex-transitive graphs and the abelian normal quotient method 
    Morris, Joy; Spiga, Pablo; Verret, Gabriel (Electronic Journal of CombinatoricsArts and ScienceDepartment of Mathematics and Computer ScienceUniversity of LethbridgeUniversity of Milano-BicoccaThe University of Western Australia, 2015)
    We characterise connected cubic graphs admitting a vertex-transitive group of automorphisms with an abelian normal subgroup that is not semiregular. We illustrate the utility of this result by using it to prove that the ...
  • Strongly regular edge-transitive graphs 
    Morris, Joy; Praeger, Cheryl E.; Spiga, Pablo (Drustvo Matematikov, Fizikov in AstronomovArts and ScienceDepartment of Mathematics and Computer ScienceUniversity of LethbridgeUniversity of Western AustraliaUniversity of Padova, 2009)
    In this paper, we examine the structure of vertex- and edge-transitive strongly regular graphs,using normal quotient reduction. We show that their reducible graphs in this family have quasi primitive automorphism groups, ...
  • Toida's conjecture is true 
    Dobson, Edward; Morris, Joy (Electronic Journal of CombinatoricsArts and ScienceDepartment of Mathematics and Computer ScienceMississippi State UniversityUniversity of Lethbridge, 2002)
    Let S be a subset of the units in Zn. Let Γ be a circulant graph of order n (a Cayley graph of Zn) such that if ij ∈ E(Γ), then i − j (mod n) ∈ S. Toida conjectured that if Γ0 is another circulant graph of order n, then Γ ...
  • Vertex-transitive digraphs with extra automorphisms that preserve the natural arc-colouring 
    Dobson, Ted; Hujdurovic, Ademir; Kutnar, Klavdija; Morris, Joy (The University of Queensland, Centre for Discrete Mathematics and ComputingArts and ScienceDepartment of Mathematics and Computer ScienceMississippi State UniversityUniversity of PrimoskaUniversity of Lethbridge, 2017)
    In a Cayley digraph on a group G, if a distinct colour is assigned to each arc-orbit under the left-regular action of G, it is not hard to show that the elements of the left-regular action of G are the only digraph ...