**NB:** A

PDF
version of this announcement (suitable for posting) is also available.

## Equivalence, roots and uniqueness of graph colorings

### Hossein Shahmohamad

Rochester Institute of Technology

###
Thursday, May 31, 2007

007 Kemeny Hall, 4 pm

Tea 3:30 pm, 300 Kemeny Hall

**Abstract: ** The chromatic polynomial P(r) of a graph G
records the number of proper vertex colorings of G with r colors.
Many properties of this polynomial as well as some basic computations
will be discussed. We will also ask and give some partial answers to
questions such as:

1. Which polynomials are chromatic polynomials?
2. Are there examples of two different graphs with the same chromatic
polynomial? 3. How do we search for infinite families of such pairs
of graphs?

If time permits, we will discuss the discovery of some
infinite families of the homeomorphs of the Petersen graph.

This talk will be accessible to graduate students.