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arXiv · 1809.04278

Classes of graphs with no long cycle as a vertex-minor are polynomially $χ$-bounded

Ringi Kim·O-joung Kwon·Sang-il Oum·Vaidy Sivaraman
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Abstract

A class $\mathcal G$ of graphs is $χ$-bounded if there is a function $f$ such that for every graph $G\in \mathcal G$ and every induced subgraph $H$ of $G$, $χ(H)\le f(ω(H))$. In addition, we say that $\mathcal G$ is polynomially $χ$-bounded if $f$ can be taken as a polynomial function. We prove that for every integer $n\ge3$, there exists a polynomial $f$ such that $χ(G)\le f(ω(G))$ for all graphs with no vertex-minor isomorphic to the cycle graph $C_n$. To prove this, we show that if $\mathcal G$ is polynomially $χ$-bounded, then so is the closure of $\mathcal G$ under taking the $1$-join operation.

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Ringi Kim, O-joung Kwon, Sang-il Oum, Vaidy Sivaraman. 2019-05-18. Classes of graphs with no long cycle as a vertex-minor are polynomially $χ$-bounded. https://doi.org/10.1016/j.jctb.2019.06.001

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