Enumeration of m-Ary Cacti
✍ Scribed by Miklós Bóna; Michel Bousquet; Gilbert Labelle; Pierre Leroux
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 253 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0196-8858
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✦ Synopsis
The purpose of this paper is to enumerate various classes of cyclically colored m-gonal plane cacti, called m-ary cacti. This combinatorial problem is motivated by the topological classification of complex polynomials having at most m critical values, studied by Zvonkin and others. We obtain explicit formulae for both Ž . labelled and unlabelled m-ary cacti, according to i the number of polygons, Ž .
Ž . ii the vertex-color distribution, iii the vertex-degree distribution of each color. We also enumerate m-ary cacti according to the order of their automorphism group. Using a generalization of Otter's formula, we express the species of m-ary cacti in terms of rooted and of pointed cacti. A variant of the m-dimensional Lagrange inversion is then used to enumerate these structures. The method of Liskovets for the enumeration of unrooted planar maps can also be adapted to m-ary cacti.
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## Introduction Let Kt denote the complete graph with t vertices. In (l), Bedrosian defined four classes of graphs, the p, s, r and m series, each formed by deleting certain branches of Kt. Formulas for the r and p series were first obtained by Weinberg (2) and are special cases of a formula due t