<p>Jordán and Tanigawa recently introduced the <i>d</i>-dimensional algebraic connectivity <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_149_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="43" /> </InlineMediaObject> <EquationSource Format="TEX">\(a_d(G)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>a</mi> <mi>d</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> of a graph <i>G</i>. This is a quantitative measure of the <i>d</i>-dimensional rigidity of <i>G</i> which generalizes the well-studied notion of spectral expansion of graphs. We present a new lower bound for <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_149_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="43" /> </InlineMediaObject> <EquationSource Format="TEX">\(a_d(G)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>a</mi> <mi>d</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> defined in terms of the spectral expansion of certain subgraphs of <i>G</i> associated with a partition of its vertices into <i>d</i> parts. In particular, we obtain a new sufficient condition for the rigidity of a graph <i>G</i>. As a first application, we prove the existence of an infinite family of <i>k</i>-regular <i>d</i>-rigidity-expander graphs for every <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_149_Article_IEq3.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="41" /> </InlineMediaObject> <EquationSource Format="TEX">\(d\ge 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>d</mi> <mo>≥</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_149_Article_IEq4.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="79" /> </InlineMediaObject> <EquationSource Format="TEX">\(k\ge 2d+1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>k</mi> <mo>≥</mo> <mn>2</mn> <mi>d</mi> <mo>+</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation>. Conjecturally, no such family of 2<i>d</i>-regular graphs exists. Second, we show that <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_149_Article_IEq5.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="111" /> </InlineMediaObject> <EquationSource Format="TEX">\(a_d(K_n)\ge \frac{1}{2}\left\lfloor \frac{n}{d}\right\rfloor \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>a</mi> <mi>d</mi> </msub> <mrow> <mo stretchy="false">(</mo> <msub> <mi>K</mi> <mi>n</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mo>≥</mo> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <mfenced close="⌋" open="⌊"> <mfrac> <mi>n</mi> <mi>d</mi> </mfrac> </mfenced> </mrow> </math></EquationSource> </InlineEquation>, which we conjecture to be essentially tight. In addition, we study the extremal values <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_149_Article_IEq6.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="43" /> </InlineMediaObject> <EquationSource Format="TEX">\(a_d(G)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>a</mi> <mi>d</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> attains if <i>G</i> is a minimally <i>d</i>-rigid graph.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

Rigidity Expander Graphs

  • Alan Lew,
  • Eran Nevo,
  • Yuval Peled,
  • Orit E. Raz

摘要

Jordán and Tanigawa recently introduced the d-dimensional algebraic connectivity \(a_d(G)\) a d ( G ) of a graph G. This is a quantitative measure of the d-dimensional rigidity of G which generalizes the well-studied notion of spectral expansion of graphs. We present a new lower bound for \(a_d(G)\) a d ( G ) defined in terms of the spectral expansion of certain subgraphs of G associated with a partition of its vertices into d parts. In particular, we obtain a new sufficient condition for the rigidity of a graph G. As a first application, we prove the existence of an infinite family of k-regular d-rigidity-expander graphs for every \(d\ge 2\) d 2 and \(k\ge 2d+1\) k 2 d + 1 . Conjecturally, no such family of 2d-regular graphs exists. Second, we show that \(a_d(K_n)\ge \frac{1}{2}\left\lfloor \frac{n}{d}\right\rfloor \) a d ( K n ) 1 2 n d , which we conjecture to be essentially tight. In addition, we study the extremal values \(a_d(G)\) a d ( G ) attains if G is a minimally d-rigid graph.