|
Abstract:
Suppose a finite number of points are placed in the plane in such a way
that they do not all lie on the same line. Must there exist a line that
connects exactly two of the
points?
Suppose each of the points are then colored red or blue in some way.
Must there exist a line that joins two or more points of one color, but
intersects none of the other color? Can you always join exactly two points of one color and
none of the other? Does anything change if you have an infinite number
of points?
We'll investigate these questions, some of which were raised more than
a century ago by the British mathematician James Joseph Sylvester.
We'll describe some novel methods used to investigate these problems,
and discuss several interesting results, including some contributions
made by undergraduate students.
Biography:
Michael Mossinghoff has a Ph.D. in mathematics from the University of
Texas at Austin, and a master's degree in computer science from
Stanford University. After teaching at Appalachian State
University and at UCLA, he joined the faculty at Davidson College in
2002, where he teaches mathematics and computer science. For the
current academic year, he is a
visiting associate professor in the Department of Mathematics at the
University of South Carolina.
His research studies algorithmic and analytic problems in number theory
and discrete geometry, and extremal problem on integer
polynomials. His article A $1
Problem won the Lester R. Ford prize for exposition from the
Mathematical Association of America in 2007. The second edition
of his book, Combinatorics
and Graph Theory, co-authored with John Harris and
Jeffry Hirst, has just been published by Springer Verlag.
|