<p>For a given graph <i>G</i>, the general position problem asks for the largest size of a set of vertices <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40840_2025_1887_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="82" /> </InlineMediaObject> <EquationSource Format="TEX">\(M \subseteq V(G)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>M</mi> <mo>⊆</mo> <mi>V</mi> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> such that no three distinct vertices of <i>M</i> belong to a common shortest path in <i>G</i>. A relaxation of this concept is based on the condition that two vertices <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40840_2025_1887_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="88" /> </InlineMediaObject> <EquationSource Format="TEX">\(x, y \in V(G)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>∈</mo> <mi>V</mi> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> are <i>M</i>-visible, meaning there exists a shortest <i>x</i>,&#xa0;<i>y</i>-path in <i>G</i> that does not pass through any vertex of <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40840_2025_1887_Article_IEq3.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="83" /> </InlineMediaObject> <EquationSource Format="TEX">\(M \setminus \{x, y\}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>M</mi> <mo lspace="0.15em" rspace="0.15em" stretchy="false">\</mo> <mo stretchy="false">{</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo stretchy="false">}</mo> </mrow> </math></EquationSource> </InlineEquation>. If every pair of vertices in <i>M</i> is <i>M</i>-visible, then <i>M</i> is called a mutual-visibility set of <i>G</i>. The cardinality of the largest mutual-visibility set of <i>G</i> is called the mutual-visibility number of <i>G</i>. Some well-known variations of this concept consider the total, outer, and dual mutual-visibility sets of a graph. We present results on the general position problem and the various mutual-visibility problems in Sierpiński triangle graphs.</p>

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Mutual-Visibility and General Position Sets in Sierpiński Triangle Graphs

  • Danilo Korže,
  • Aleksander Vesel

摘要

For a given graph G, the general position problem asks for the largest size of a set of vertices \(M \subseteq V(G)\) M V ( G ) such that no three distinct vertices of M belong to a common shortest path in G. A relaxation of this concept is based on the condition that two vertices \(x, y \in V(G)\) x , y V ( G ) are M-visible, meaning there exists a shortest xy-path in G that does not pass through any vertex of \(M \setminus \{x, y\}\) M \ { x , y } . If every pair of vertices in M is M-visible, then M is called a mutual-visibility set of G. The cardinality of the largest mutual-visibility set of G is called the mutual-visibility number of G. Some well-known variations of this concept consider the total, outer, and dual mutual-visibility sets of a graph. We present results on the general position problem and the various mutual-visibility problems in Sierpiński triangle graphs.