2009
Swartz, Eric
Seress, Akos
A near-polygonal graph is a graph Γ which has a set C of m-cycles for
some positive integer m such that each 2-path of Γ is contained in
exactly one cycle in C. If m is the girth of Γ then the graph is called
polygonal. Up until now, the only examples of 2-arc transitive
polygonal graphs with arbitrarily large valency had girth no larger
than seven, and the 2-arc transitive polygonal graph with largest girth
had valency five and girth twenty-three (in fact, even with no
restrictions on the automorphism group, there were no examples of
polygonal graphs with odd girth greater than twenty-three). This thesis
provides a construction of an infinite family of polygonal graphs of
arbitrary girth m with 2-arc transitive automorphism groups, showing
that there are 2-arc transitive polygonal graphs of arbitrarily large
valency for each girth m. Furthermore, this thesis also provides a
construction that, given a polygonal graph of valency r and girth m,
produces a polygonal graph of valency r and girth 3m, and that the
graphs constructed via this method will be 2-arc transitive if the
original graph was 2-arc transitive. Finally, this thesis provides a
construction of a new infinite family of near-polygonal graphs of
valency 10 and a method for determining which graphs can have a given
girth, which yields a few new examples of polygonal graphs.

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