Interviene
Marco BARBIERI
Università di Pavia
Abstract
The Praeger-Xu graphs are the elephant in the room of 4-valent symmetric graphs: they act as natural counterexamples to many questions regarding this class of graphs, both for being difficult to handle computationally and for appearing as obstructions while using the normal quotient method. In this talk, after a brief recollection of some basic facts on vertex- and arc-transitive graphs, we will try to explain why the Praeger-Xu graphs are ubiquitous, and where they popped up in some recent results.
