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Upper bounds on the average number of colors in the non-equivalent colorings of a graph

Alain Hertz, Hadrien Mélot, Sébastien Bonte, Gauvain Devillez, Pierre Hauweele

TL;DR

A general upper bound on A(G), the average number of colors in the non-equivalent colorings of a graph G, is given that is valid for all graphs G and a more precise one for graphs G of order n and maximum degree.

Abstract

A coloring of a graph is an assignment of colors to its vertices such that adjacent vertices have different colors. Two colorings are equivalent if they induce the same partition of the vertex set into color classes. Let $\mathcal{A}(G)$ be the average number of colors in the non-equivalent colorings of a graph $G$. We give a general upper bound on $\mathcal{A}(G)$ that is valid for all graphs $G$ and a more precise one for graphs $G$ of order $n$ and maximum degree $Δ(G)\in \{1,2,n-2\}$.

Upper bounds on the average number of colors in the non-equivalent colorings of a graph

TL;DR

A general upper bound on A(G), the average number of colors in the non-equivalent colorings of a graph G, is given that is valid for all graphs G and a more precise one for graphs G of order n and maximum degree.

Abstract

A coloring of a graph is an assignment of colors to its vertices such that adjacent vertices have different colors. Two colorings are equivalent if they induce the same partition of the vertex set into color classes. Let be the average number of colors in the non-equivalent colorings of a graph . We give a general upper bound on that is valid for all graphs and a more precise one for graphs of order and maximum degree .

Paper Structure

This paper contains 5 sections, 18 theorems, 40 equations, 1 figure, 1 table.

Key Result

Proposition 1

Let $v$ be a simplicial vertex of degree at least one in a graph $G$, and let $w$ be one of its neighbors in $G$. Then $\mathcal{A}(G)>\mathcal{A}(G-vw)$.

Figures (1)

  • Figure 1: The non-equivalent colorings of ${\sf P}_{4}$.

Theorems & Definitions (31)

  • Proposition 1: HertzLB
  • Proposition 2: HertzLB
  • Proposition 3: Hertz21
  • Proposition 4: HertzLB
  • Lemma 5
  • proof
  • Lemma 6
  • proof
  • Lemma 7
  • proof
  • ...and 21 more