<p>Let <i>G</i> be a finite group. A simple undirected graph <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\Gamma _{G}^{RI}\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi mathvariant="normal">Γ</mi> <mrow> <mi>G</mi> </mrow> <mrow> <mi mathvariant="italic">RI</mi> </mrow> </msubsup> </math></EquationSource> </InlineEquation> is called a result involution graph of <i>G</i> if the vertex set of <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\Gamma _{G}^{RI}\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi mathvariant="normal">Γ</mi> <mrow> <mi>G</mi> </mrow> <mrow> <mi mathvariant="italic">RI</mi> </mrow> </msubsup> </math></EquationSource> </InlineEquation> is the whole group <i>G</i> and two distinct vertices are adjacent if their product is an involution in <i>G</i>. In this paper, some properties of <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\Gamma _{G}^{RI}\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi mathvariant="normal">Γ</mi> <mrow> <mi>G</mi> </mrow> <mrow> <mi mathvariant="italic">RI</mi> </mrow> </msubsup> </math></EquationSource> </InlineEquation> are obtained. We show that <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\Gamma _{G}^{RI}\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi mathvariant="normal">Γ</mi> <mrow> <mi>G</mi> </mrow> <mrow> <mi mathvariant="italic">RI</mi> </mrow> </msubsup> </math></EquationSource> </InlineEquation> is a connected graph if and only if <i>G</i> is generated by some involutions, <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\Gamma _{G}^{RI}\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi mathvariant="normal">Γ</mi> <mrow> <mi>G</mi> </mrow> <mrow> <mi mathvariant="italic">RI</mi> </mrow> </msubsup> </math></EquationSource> </InlineEquation> is a complete graph if and only if <i>G</i> is an elementary abelian 2-group, and <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\Gamma _{G}^{RI}\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi mathvariant="normal">Γ</mi> <mrow> <mi>G</mi> </mrow> <mrow> <mi mathvariant="italic">RI</mi> </mrow> </msubsup> </math></EquationSource> </InlineEquation> is a complete bipartite graph if and only if <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(G=M\rtimes T\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>G</mi> <mo>=</mo> <mi>M</mi> <mo>⋊</mo> <mi>T</mi> </mrow> </math></EquationSource> </InlineEquation>, where <i>M</i> is a abelian group of odd order, <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(|T|=2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">|</mo> <mi>T</mi> <mo stretchy="false">|</mo> <mo>=</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(C_M(T)=1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>C</mi> <mi>M</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>T</mi> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation>. Finally, we also determine the structure of <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(\Gamma _{G}^{RI}\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi mathvariant="normal">Γ</mi> <mrow> <mi>G</mi> </mrow> <mrow> <mi mathvariant="italic">RI</mi> </mrow> </msubsup> </math></EquationSource> </InlineEquation> when <i>G</i> is a finite 2-group which possesses a cyclic maximal subgroup.</p>

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On result involution graphs of finite groups

  • Liang Cui,
  • Wei Meng,
  • Jiakuan Lu

摘要

Let G be a finite group. A simple undirected graph \(\Gamma _{G}^{RI}\) Γ G RI is called a result involution graph of G if the vertex set of \(\Gamma _{G}^{RI}\) Γ G RI is the whole group G and two distinct vertices are adjacent if their product is an involution in G. In this paper, some properties of \(\Gamma _{G}^{RI}\) Γ G RI are obtained. We show that \(\Gamma _{G}^{RI}\) Γ G RI is a connected graph if and only if G is generated by some involutions, \(\Gamma _{G}^{RI}\) Γ G RI is a complete graph if and only if G is an elementary abelian 2-group, and \(\Gamma _{G}^{RI}\) Γ G RI is a complete bipartite graph if and only if \(G=M\rtimes T\) G = M T , where M is a abelian group of odd order, \(|T|=2\) | T | = 2 and \(C_M(T)=1\) C M ( T ) = 1 . Finally, we also determine the structure of \(\Gamma _{G}^{RI}\) Γ G RI when G is a finite 2-group which possesses a cyclic maximal subgroup.