{ "id": "1605.04267", "version": "v1", "published": "2016-05-13T17:40:02.000Z", "updated": "2016-05-13T17:40:02.000Z", "title": "$(δ, χ_{_{\\sf FF}})$-bounded families of graphs", "authors": [ "Manouchehr Zaker" ], "comment": "Accepted for publication in Utilitas Mathematica", "categories": [ "math.CO" ], "abstract": "For any graph $G$, the First-Fit (or Grundy) chromatic number of $G$, denoted by $\\chi_{_{\\sf FF}}(G)$, is defined as the maximum number of colors used by the First-Fit (greedy) coloring of the vertices of $G$. We call a family $\\mathcal{F}$ of graphs $(\\delta, \\chi_{_{\\sf FF}})$-bounded if there exists a function $f(x)$ with $f(x)\\rightarrow \\infty$ as $x\\rightarrow \\infty$ such that for any graph $G$ from the family one has $\\chi_{_{\\sf FF}}(G)\\geq f(\\delta(G))$, where $\\delta(G)$ is the minimum degree of $G$. We first give some results concerning $(\\delta, \\chi_{_{\\sf FF}})$-bounded families and obtain a few such families. Then we prove that for any positive integer $\\ell$, $Forb(K_{\\ell,\\ell})$ is $(\\delta, \\chi_{_{\\sf FF}})$-bounded, where $K_{\\ell,\\ell}$ is complete bipartite graph. We conjecture that if $G$ is any $C_4$-free graph then $\\chi_{_{\\sf FF}}(G)\\geq \\delta(G)+1$. We prove the validity of this conjecture for chordal graphs, complement of bipartite graphs and graphs with low minimum degree.", "revisions": [ { "version": "v1", "updated": "2016-05-13T17:40:02.000Z" } ], "analyses": { "subjects": [ "05C15", "05C07", "05C85", "05C38" ], "keywords": [ "bounded families", "complete bipartite graph", "low minimum degree", "chromatic number", "maximum number" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }