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Generating Functions For Kernels of Digraphs (Enumeration & Asymptotics for Nim Games)

Cyril Banderier·Jean-Marie Le Bars·Vlady Ravelomanana
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Abstract

In this article, we study directed graphs (digraphs) with a coloring constraint due to Von Neumann and related to Nim-type games. This is equivalent to the notion of kernels of digraphs, which appears in numerous fields of research such as game theory, complexity theory, artificial intelligence (default logic, argumentation in multi-agent systems), 0-1 laws in monadic second order logic, combinatorics (perfect graphs)... Kernels of digraphs lead to numerous difficult questions (in the sense of NP-completeness, #P-completeness). However, we show here that it is possible to use a generating function approach to get new informations: we use technique of symbolic and analytic combinatorics (generating functions and their singularities) in order to get exact and asymptotic results, e.g. for the existence of a kernel in a circuit or in a unicircuit digraph. This is a first step toward a generatingfunctionology treatment of kernels, while using, e.g., an approach "a la Wright". Our method could be applied to more general "local coloring constraints" in decomposable combinatorial structures.

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BibTeXRIS

Cyril Banderier, Jean-Marie Le Bars, Vlady Ravelomanana. 2004-11-06. Generating Functions For Kernels of Digraphs (Enumeration & Asymptotics for Nim Games). https://arxiv.org/abs/math/0411138

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