The structure of rational functions of two real variables which take few distinct values on large (finite) Cartesian products is described. As an application, a problem of G. Purdy is solved on finite subsets of the plane which determine few distinct distances.
A Technology for Reverse-Engineering a Combinatorial Problem from a Rational Generating Function
✍ Scribed by E. Barcucci; A. Del Lungo; A. Frosini; S. Rinaldi
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 178 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0196-8858
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✦ Synopsis
In this paper, we tackle the problem of giving, by means of a regular language, a Ž . combinatorial interpretation of a positive sequence f defined by a linear n recurrence with integer coefficients. We propose two algorithms able to determine Ž . Ž . if the rational generating function of f , f x , is the generating function of some n regular language, and, in the affirmative case, to find it. We illustrate some applications of this method to combinatorial object enumeration problems and bijective combinatorics and discuss an open problem regarding languages having a rational generating function.
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