<p>A map is considered to be semi-equivelar if all of the face-cycles at its vertices are of the same type. In this article, we show that a surface with Euler characteristic of <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40010_2025_923_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="24" /> </InlineMediaObject> <EquationSource Format="TEX">\(-2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>-</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation> admits 39 distinct types of semi-equivelar maps. Moreover, we classify (up to isomorphism) a specific category of semi-equivelar maps on this surface. This approach can be extended to classify the other types of maps. For every orientable surface of genus <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40010_2025_923_Article_IEq2.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="42" /> </InlineMediaObject> <EquationSource Format="TEX">\(g&gt; 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>g</mi> <mo>&gt;</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation>, there is a regular covering of an orientable surface with genus 2 by the cyclic group of covering transformations. This result was algebraically demonstrated by Harvey&#xa0;(Q J Math 17:86–97, 1966). In this article, we provide a combinatorial explanation of a similar result for a class of semi-equivelar maps using the concept of a connected sum. For semi-equivelar maps on surfaces with Euler characteristic <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40010_2025_923_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="24" /> </InlineMediaObject> <EquationSource Format="TEX">\(-2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>-</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation>, we demonstrate the existence of <i>m</i>-th covering maps on higher genus surfaces. We also show that the symmetry groups of the <i>m</i>-th covering maps are either <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40010_2025_923_Article_IEq4.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="24" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathbb {D}_m\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="double-struck">D</mi> <mi>m</mi> </msub> </math></EquationSource> </InlineEquation> (dihedral group of order 2<i>m</i>) or <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40010_2025_923_Article_IEq5.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="24" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathbb {Z}_m\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="double-struck">Z</mi> <mi>m</mi> </msub> </math></EquationSource> </InlineEquation> (cyclic group of order <i>m</i>).</p>

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Dihedral and Cyclic Covers of a Class of Maps on Surfaces

  • Marbarisha M. Kharkongor,
  • Debashis Bhowmik,
  • Dipendu Maity

摘要

A map is considered to be semi-equivelar if all of the face-cycles at its vertices are of the same type. In this article, we show that a surface with Euler characteristic of \(-2\) - 2 admits 39 distinct types of semi-equivelar maps. Moreover, we classify (up to isomorphism) a specific category of semi-equivelar maps on this surface. This approach can be extended to classify the other types of maps. For every orientable surface of genus \(g> 2\) g > 2 , there is a regular covering of an orientable surface with genus 2 by the cyclic group of covering transformations. This result was algebraically demonstrated by Harvey (Q J Math 17:86–97, 1966). In this article, we provide a combinatorial explanation of a similar result for a class of semi-equivelar maps using the concept of a connected sum. For semi-equivelar maps on surfaces with Euler characteristic \(-2\) - 2 , we demonstrate the existence of m-th covering maps on higher genus surfaces. We also show that the symmetry groups of the m-th covering maps are either \(\mathbb {D}_m\) D m (dihedral group of order 2m) or \(\mathbb {Z}_m\) Z m (cyclic group of order m).