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Lethbridge Number Theory and Combinatorics Seminar
Date:
November 28, 2016
Time:
12:00-12:50pm
Lecturer(s):
Gabriel Verret (University of Auckland, New Zealand)
Location:
University of Lethbridge
Topic:
Vertex-primitive digraphs having vertices with almost equal neighbourhoods
Description (in plain text format):
A permutation group G on X is transitive if for every x and y in X, there exists g in G mapping x to y. The group G is called primitive if, in addition, it preserves no nontrivial partition of X. Let Gamma be a vertex-primitive digraph, that is, its automorphism group acts primitively on its vertex-set. It is not hard to see that, in this case, Gamma cannot have two distinct vertices with equal neighbourhoods, unless Gamma is in some sense trivial. I will discuss some recent results about the case when Gamma has two vertices with “almost” equal neighbourhoods, and how these results were used to answer a question of Araújo and Cameron about synchronising groups. (This is joint work with Pablo Spiga.)
Other Information:
Location: C756 University Hall
Web page: http://www.cs.uleth.ca/~nathanng/ntcoseminar/
Contact:
Barb Hodgson | hodgsonb@uleth.ca | (403) 329-2470 | uleth.ca/artsci/math-computer-science
