Bijections and the Riordan group
One of the cornerstone ideas in mathematics is to take a problem and to look at it in a bigger space. In this paper we examine combinatorial sequences in the context of the Riordan group. Various subgroups of the Riordan group each give us a different view of the original sequence. In many cases this leads to both a combinatorial interpretation and to ECO rewriting rules. In this paper we will concentrate on just four of the subgroups of the Riordan group to demonstrate some of the possibilities of this approach. (C) 2003 Elsevier B.V. All rights reserved.
riordan group checkerboard subgroup catalan numbers