Jessica
Dickson
Department of
Mathematics and Statistics
Washington State University
Title: The
Overlays of Riordan Arrays
Abstract: In this talk we discuss
new and potential ways in which machinery such as
templates and overlays can be applied to
well-studied arrays, specifically Riordan arrays.
An array can be thought of
as a matrix that extends infinitely in all
directions.
Operators X and Y shift an array
right by one column or up by one row, respectively.
A polynomial in X and Y that
annihilates an array is called a ``template" whereas
an ``overlay" is an array with finite support that
contains the coefficients of a template.
Riordan arrays are lower
triangular arrays that extend infinitely only to the
right and downwards. They were originally motivated
by a generalization of Pascal's triangle and can be
described in one of two ways: Either column-wise by
their generating functions or row-wise by their
associated patterned sequence. This pattern sequence
often corresponds to a natural representation as an
overlay. In this talk we explore that representation
and the requirements for such a representation to
exist.