23 research outputs found
Locally arc-transitive graphs of valence with trivial edge kernel
In this paper we consider connected locally -arc-transitive graphs with
vertices of valence 3 and 4, such that the kernel of the action
of an edge-stabiliser on the neighourhood is
trivial. We find nineteen finitely presented groups with the property that any
such group is a quotient of one of these groups. As an application, we
enumerate all connected locally arc-transitive graphs of valence on at
most 350 vertices whose automorphism group contains a locally arc-transitive
subgroup with
Resolution of a conjecture about linking ring structures
An LR-structure is a tetravalent vertex-transitive graph together with a
special type of a decomposition of its edge-set into cycles. LR-structures were
introduced in a paper by P. Poto\v{c}nik and S. Wilson, titled `Linking rings
structures and tetravalent semisymmetric graphs', in Ars Math. Contemp. 7
(2014), as a tool to study tetravalent semisymmetric graphs of girth 4. In this
paper, we use the methods of group amalgams to resolve some problems left open
in the above-mentioned paper
Core-Free, Rank Two Coset Geometries from Edge-Transitive Bipartite Graphs
It is known that the Levi graph of any rank two coset geometry is an
edge-transitive graph, and thus coset geometries can be used to construct many
edge transitive graphs. In this paper, we consider the reverse direction.
Starting from edge- transitive graphs, we construct all associated core-free,
rank two coset geometries. In particular, we focus on 3-valent and 4-valent
graphs, and are able to construct coset geometries arising from these graphs.
We summarize many properties of these coset geometries in a sequence of tables;
in the 4-valent case we restrict to graphs that have relatively small
vertex-stabilizers
A note on pentavalent s-transitive graphs
AbstractA graph, with a group G of its automorphisms, is said to be (G,s)-transitive if G is transitive on s-arcs but not on (s+1)-arcs of the graph. Let X be a connected (G,s)-transitive graph for some s≥1, and let Gv be the stabilizer of a vertex v∈V(X) in G. In this paper, we determine the structure of Gv when X has valency 5 and Gv is non-solvable. Together with the results of Zhou and Feng [J.-X. Zhou, Y.-Q. Feng, On symmetric graphs of valency five, Discrete Math. 310 (2010) 1725–1732], the structure of Gv is completely determined when X has valency 5. For valency 3 or 4, the structure of Gv is known