<p>A <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({[}z,r;g{]}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">[</mo> <mi>z</mi> <mo>,</mo> <mi>r</mi> <mo>;</mo> <mi>g</mi> <mo stretchy="false">]</mo> </mrow> </math></EquationSource> </InlineEquation>-mixed cage is a mixed graph of minimum order such that each vertex has <i>z</i> in-arcs, <i>z</i> out-arcs, <i>r</i> edges, and it has girth <i>g</i>, and the minimum order for <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({[}z,r;g{]}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">[</mo> <mi>z</mi> <mo>,</mo> <mi>r</mi> <mo>;</mo> <mi>g</mi> <mo stretchy="false">]</mo> </mrow> </math></EquationSource> </InlineEquation>-mixed graphs is denoted by <i>n</i>[<i>z</i>,&#xa0;<i>r</i>;&#xa0;<i>g</i>]. In this paper, we present an infinite family of mixed graphs with girth 6 that improves, in some cases, the families that we give in G. Araujo-Pardo and L. Mendoza-Cadena. <i>On Mixed Cages of girth 6</i>, arXiv:2401.14768v2. In particular, if <i>q</i> is an even prime power, we construct a family of graphs that satisfies <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(n[\frac{q}{4},q;6]\le 4q^{2}-4\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mrow> <mo stretchy="false">[</mo> <mfrac> <mi>q</mi> <mn>4</mn> </mfrac> <mo>,</mo> <mi>q</mi> <mo>;</mo> <mn>6</mn> <mo stretchy="false">]</mo> </mrow> <mo>≤</mo> <mn>4</mn> <msup> <mi>q</mi> <mn>2</mn> </msup> <mo>-</mo> <mn>4</mn> </mrow> </math></EquationSource> </InlineEquation>, and if <i>q</i> is an odd prime power, and <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\frac{q-3}{2}\)</EquationSource> <EquationSource Format="MATHML"><math> <mfrac> <mrow> <mi>q</mi> <mo>-</mo> <mn>3</mn> </mrow> <mn>2</mn> </mfrac> </math></EquationSource> </InlineEquation> is odd, then our family satisfies that <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(n[\frac{q-1}{4},q;6]\le 4q^2-4\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mrow> <mo stretchy="false">[</mo> <mfrac> <mrow> <mi>q</mi> <mo>-</mo> <mn>1</mn> </mrow> <mn>4</mn> </mfrac> <mo>,</mo> <mi>q</mi> <mo>;</mo> <mn>6</mn> <mo stretchy="false">]</mo> </mrow> <mo>≤</mo> <mn>4</mn> <msup> <mi>q</mi> <mn>2</mn> </msup> <mo>-</mo> <mn>4</mn> </mrow> </math></EquationSource> </InlineEquation>, otherwise <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(n[\frac{q-3}{4},q;6]\le 4q^2-4\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mrow> <mo stretchy="false">[</mo> <mfrac> <mrow> <mi>q</mi> <mo>-</mo> <mn>3</mn> </mrow> <mn>4</mn> </mfrac> <mo>,</mo> <mi>q</mi> <mo>;</mo> <mn>6</mn> <mo stretchy="false">]</mo> </mrow> <mo>≤</mo> <mn>4</mn> <msup> <mi>q</mi> <mn>2</mn> </msup> <mo>-</mo> <mn>4</mn> </mrow> </math></EquationSource> </InlineEquation>.</p>

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New upper bounds on the order of mixed cages of girth 6

  • Gabriela Araujo-Pardo,
  • Mirabel Mendoza-Cadena

摘要

A \({[}z,r;g{]}\) [ z , r ; g ] -mixed cage is a mixed graph of minimum order such that each vertex has z in-arcs, z out-arcs, r edges, and it has girth g, and the minimum order for \({[}z,r;g{]}\) [ z , r ; g ] -mixed graphs is denoted by n[zrg]. In this paper, we present an infinite family of mixed graphs with girth 6 that improves, in some cases, the families that we give in G. Araujo-Pardo and L. Mendoza-Cadena. On Mixed Cages of girth 6, arXiv:2401.14768v2. In particular, if q is an even prime power, we construct a family of graphs that satisfies \(n[\frac{q}{4},q;6]\le 4q^{2}-4\) n [ q 4 , q ; 6 ] 4 q 2 - 4 , and if q is an odd prime power, and \(\frac{q-3}{2}\) q - 3 2 is odd, then our family satisfies that \(n[\frac{q-1}{4},q;6]\le 4q^2-4\) n [ q - 1 4 , q ; 6 ] 4 q 2 - 4 , otherwise \(n[\frac{q-3}{4},q;6]\le 4q^2-4\) n [ q - 3 4 , q ; 6 ] 4 q 2 - 4 .