<p>Given a group <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10801_2025_1447_Article_IEq1.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="16" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal {G}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="script">G</mi> </math></EquationSource> </InlineEquation>, let <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10801_2025_1447_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="36" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha (\mathcal {G})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>α</mi> <mo stretchy="false">(</mo> <mi mathvariant="script">G</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> (resp. <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10801_2025_1447_Article_IEq3.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="46" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha ^{P}(\mathcal {G})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>α</mi> <mi>P</mi> </msup> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="script">G</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>) denote the minimal number of vertices among all graphs (resp. planar graphs) <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10801_2025_1447_Article_IEq4.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="12" /> </InlineMediaObject> <EquationSource Format="TEX">\(\Gamma \)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Γ</mi> </math></EquationSource> </InlineEquation> such that <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10801_2025_1447_Article_IEq5.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="78" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathop {\textrm{Aut}}\Gamma \cong \mathcal {G}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mtext>Aut</mtext> <mi mathvariant="normal">Γ</mi> <mo>≅</mo> <mi mathvariant="script">G</mi> </mrow> </math></EquationSource> </InlineEquation>. Over the years, several researchers have constructed vertex-minimal planar graphs with cyclic group symmetry. For an abelian group <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10801_2025_1447_Article_IEq1.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="16" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal {G}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="script">G</mi> </math></EquationSource> </InlineEquation>, we construct planar graphs whose automorphism group is isomorphic to <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10801_2025_1447_Article_IEq1.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="16" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal {G}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="script">G</mi> </math></EquationSource> </InlineEquation>. Consequently, we obtain suitable upper bounds for <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10801_2025_1447_Article_IEq8.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="46" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha ^P(\mathcal {G})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>α</mi> <mi>P</mi> </msup> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="script">G</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> with equability holding for a large class of abelian groups. This partially addresses one of the open questions raised by Archer et al. (J Algebr Combin 54:1–15, 2021): find the value of <InlineEquation ID="IEq9"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10801_2025_1447_Article_IEq3.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="46" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha ^{P}(\mathcal {G})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>α</mi> <mi>P</mi> </msup> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="script">G</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> when <InlineEquation ID="IEq10"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10801_2025_1447_Article_IEq1.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="16" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal {G}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="script">G</mi> </math></EquationSource> </InlineEquation> is an abelian group. Further, we classify all finite abelian groups <InlineEquation ID="IEq11"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10801_2025_1447_Article_IEq1.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="16" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal {G}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="script">G</mi> </math></EquationSource> </InlineEquation> such that <InlineEquation ID="IEq12"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10801_2025_1447_Article_IEq12.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="102" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha (\mathcal {G})=\alpha ^{P}(\mathcal {G})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>α</mi> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="script">G</mi> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <msup> <mi>α</mi> <mi>P</mi> </msup> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="script">G</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, giving a partial answer to another question asked by Archer et al.</p>

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On planar graphs with abelian automorphism groups

  • Kirti Sahu,
  • Ranjit Mehatari

摘要

Given a group \(\mathcal {G}\) G , let \(\alpha (\mathcal {G})\) α ( G ) (resp. \(\alpha ^{P}(\mathcal {G})\) α P ( G ) ) denote the minimal number of vertices among all graphs (resp. planar graphs) \(\Gamma \) Γ such that \(\mathop {\textrm{Aut}}\Gamma \cong \mathcal {G}\) Aut Γ G . Over the years, several researchers have constructed vertex-minimal planar graphs with cyclic group symmetry. For an abelian group \(\mathcal {G}\) G , we construct planar graphs whose automorphism group is isomorphic to \(\mathcal {G}\) G . Consequently, we obtain suitable upper bounds for \(\alpha ^P(\mathcal {G})\) α P ( G ) with equability holding for a large class of abelian groups. This partially addresses one of the open questions raised by Archer et al. (J Algebr Combin 54:1–15, 2021): find the value of \(\alpha ^{P}(\mathcal {G})\) α P ( G ) when \(\mathcal {G}\) G is an abelian group. Further, we classify all finite abelian groups \(\mathcal {G}\) G such that \(\alpha (\mathcal {G})=\alpha ^{P}(\mathcal {G})\) α ( G ) = α P ( G ) , giving a partial answer to another question asked by Archer et al.