Title
Vertex-transitive digraphs with extra automorphisms that preserve the natural arc-colouring.
Abstract
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 auto-morphisms that preserve this colouring. In this paper, we show that the equivalent statement is not true in the most straightforward generalisation to G-vertex-transitive digraphs, even if we restrict the situation to avoid some obvious potential problems. Specifically, we display an infinite family of 2-closed groups G, and a G-arc-transitive digraph on each (without any digons) for which there exists an automorphism of the digraph that is not an element of G (it is an automorphism of G). Since the digraph is G-arc-transitive, the arcs would all be assigned the same colour under the colouring by arc-orbits, so this digraph automorphism is colour-preserving.
Year
Venue
DocType
2017
AUSTRALASIAN JOURNAL OF COMBINATORICS
Journal
Volume
ISSN
Citations 
67
2202-3518
0
PageRank 
References 
Authors
0.34
0
4
Name
Order
Citations
PageRank
Ted Dobson111.38
Ademir Hujdurović21810.06
Klavdija Kutnar313824.35
Joy Morris47816.06