<p>We show that a <i>k</i>-uniform hypergraph on <i>n</i> vertices has a spanning subgraph homeomorphic to the <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_169_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="52" /> </InlineMediaObject> <EquationSource Format="TEX">\((k - 1)\)</EquationSource> </InlineEquation>-dimensional sphere provided that <i>H</i> has no isolated vertices and each set of <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_169_Article_IEq2.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="40" /> </InlineMediaObject> <EquationSource Format="TEX">\(k - 1\)</EquationSource> </InlineEquation> vertices supported by an edge is contained in at least <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_169_Article_IEq3.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="79" /> </InlineMediaObject> <EquationSource Format="TEX">\(n/2 + o(n)\)</EquationSource> </InlineEquation> edges. This gives a topological extension of Dirac’s theorem and asymptotically confirms a conjecture of Georgakopoulos, Haslegrave, Montgomery, and Narayanan. Unlike typical results in the area, our proof does not rely on the Absorption Method, the Regularity Lemma or the Blow-up Lemma. Instead, we use a recently introduced framework that is based on covering the vertex set of the host graph with a family of complete blow-ups.</p>

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Spanning Spheres in Dirac Hypergraphs

  • Freddie Illingworth,
  • Richard Lang,
  • Alp Müyesser,
  • Olaf Parczyk,
  • Amedeo Sgueglia

摘要

We show that a k-uniform hypergraph on n vertices has a spanning subgraph homeomorphic to the \((k - 1)\) -dimensional sphere provided that H has no isolated vertices and each set of \(k - 1\) vertices supported by an edge is contained in at least \(n/2 + o(n)\) edges. This gives a topological extension of Dirac’s theorem and asymptotically confirms a conjecture of Georgakopoulos, Haslegrave, Montgomery, and Narayanan. Unlike typical results in the area, our proof does not rely on the Absorption Method, the Regularity Lemma or the Blow-up Lemma. Instead, we use a recently introduced framework that is based on covering the vertex set of the host graph with a family of complete blow-ups.