<p>A majority coloring of a directed graph is a vertex-coloring in which every vertex has the same color as at most half of its out-neighbors. Kreutzer et al. conjectured that every digraph is majority 3-colorable. For an integer <i>k</i> ≥ 2, <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10255_2025_2_Article_IEq1.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="10" /> </InlineMediaObject> <EquationSource Format="TEX">\({1 \over {k}}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mfrac> <mn>1</mn> <mi>k</mi> </mfrac> </mrow> </math></EquationSource> </InlineEquation>-majority coloring of a directed graph is a vertex-coloring in which every vertex <i>v</i> has the same color as at most <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10255_2025_2_Article_IEq2.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="49" /> </InlineMediaObject> <EquationSource Format="TEX">\({1 \over {k}}{d^{+}}(v)\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mfrac> <mn>1</mn> <mrow> <mi>k</mi> </mrow> </mfrac> </mrow> <mrow> <msup> <mi>d</mi> <mrow> <mo>+</mo> </mrow> </msup> </mrow> <mo stretchy="false">(</mo> <mi>v</mi> <mo stretchy="false">)</mo> </math></EquationSource> </InlineEquation> of its out-neighbors. Girão et al. proved that every digraph admits a <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10255_2025_2_Article_IEq3.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="10" /> </InlineMediaObject> <EquationSource Format="TEX">\({1 \over {k}}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mfrac> <mn>1</mn> <mi>k</mi> </mfrac> </mrow> </math></EquationSource> </InlineEquation>-majority 2<i>k</i>-coloring. In this paper, we prove that Kreutzer’s conjecture is true for digraphs under some conditions, which improves Kreutzer’s results, also we obtained some results of <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10255_2025_2_Article_IEq4.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="10" /> </InlineMediaObject> <EquationSource Format="TEX">\({1 \over {k}}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mfrac> <mn>1</mn> <mi>k</mi> </mfrac> </mrow> </math></EquationSource> </InlineEquation>-majority coloring of digraphs. Moreover, we discuss the majority 3-coloring of random digraphs with some conditions.</p>

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Some New Results on Majority Coloring of Digraphs

  • Jian-sheng Cai,
  • Wei-hao Xia,
  • Gui-ying Yan

摘要

A majority coloring of a directed graph is a vertex-coloring in which every vertex has the same color as at most half of its out-neighbors. Kreutzer et al. conjectured that every digraph is majority 3-colorable. For an integer k ≥ 2, \({1 \over {k}}\) 1 k -majority coloring of a directed graph is a vertex-coloring in which every vertex v has the same color as at most \({1 \over {k}}{d^{+}}(v)\) 1 k d + ( v ) of its out-neighbors. Girão et al. proved that every digraph admits a \({1 \over {k}}\) 1 k -majority 2k-coloring. In this paper, we prove that Kreutzer’s conjecture is true for digraphs under some conditions, which improves Kreutzer’s results, also we obtained some results of \({1 \over {k}}\) 1 k -majority coloring of digraphs. Moreover, we discuss the majority 3-coloring of random digraphs with some conditions.