Thursday, April 5, 2018 1:30 pm
-
1:30 pm
EDT (GMT -04:00)
Title: Graphs and Unitals
| Speaker: | Professor Chris Godsil |
| Affiliation: | University of Waterloo |
| Room: | MC 6486 |
Abstract: If
N
is
a
symmetric
incidence
matrix
for
a
projective
plane
of
order
n,
then
the
trace
of
N
is
at
least
n
and
at
most
n^3/2
.
If
the
upper
bound
is
tight,
the
corresponding
subset
of
points
of
the
plane
form
what
is
called
a
unital.
These
are
interesting
structures,
giving
rise
to
2-designs
with
a
2-transitive
group
of
automorphisms.
However
my
focus
will
be
on
the
points
not
in
the
unital,
because
they
are
the
vertex
sets
of
some
interesting
graphs.