<p>The Liebeck–Nikolov–Shalev conjecture (Bull Lond Math Soc 44(3):469–472, 2012) asserts that, for any finite simple non-abelian group <i>G</i> and any set <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_155_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="54" /> </InlineMediaObject> <EquationSource Format="TEX">\(A\subseteq G\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>A</mi> <mo>⊆</mo> <mi>G</mi> </mrow> </math></EquationSource> </InlineEquation> with <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_155_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="56" /> </InlineMediaObject> <EquationSource Format="TEX">\(|A|\ge 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">|</mo> <mi>A</mi> <mo stretchy="false">|</mo> <mo>≥</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation>, <i>G</i> is the product of at most <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_155_Article_IEq3.gif" Format="GIF" Height="28" Rendition="HTML" Resolution="72" Type="Linedraw" Width="53" /> </InlineMediaObject> <EquationSource Format="TEX">\(N\frac{\log |G|}{\log |A|}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>N</mi> <mfrac> <mrow> <mo>log</mo> <mo stretchy="false">|</mo> <mi>G</mi> <mo stretchy="false">|</mo> </mrow> <mrow> <mo>log</mo> <mo stretchy="false">|</mo> <mi>A</mi> <mo stretchy="false">|</mo> </mrow> </mfrac> </mrow> </math></EquationSource> </InlineEquation> conjugates of <i>A</i>, for some absolute constant <i>N</i>. For <i>G</i> of Lie type, we prove that for any <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_155_Article_IEq4.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="40" /> </InlineMediaObject> <EquationSource Format="TEX">\(\varepsilon &gt;0\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>ε</mi> <mo>&gt;</mo> <mn>0</mn> </mrow> </math></EquationSource> </InlineEquation> there is some <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_155_Article_IEq5.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="22" /> </InlineMediaObject> <EquationSource Format="TEX">\(N_{\varepsilon }\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>N</mi> <mi>ε</mi> </msub> </math></EquationSource> </InlineEquation> for which <i>G</i> is the product of at most <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_155_Article_IEq6.gif" Format="GIF" Height="36" Rendition="HTML" Resolution="72" Type="Linedraw" Width="102" /> </InlineMediaObject> <EquationSource Format="TEX">\(N_{\varepsilon }\left( \frac{\log |G|}{\log |A|}\right) ^{1+\varepsilon }\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>N</mi> <mi>ε</mi> </msub> <msup> <mfenced close=")" open="("> <mfrac> <mrow> <mo>log</mo> <mo stretchy="false">|</mo> <mi>G</mi> <mo stretchy="false">|</mo> </mrow> <mrow> <mo>log</mo> <mo stretchy="false">|</mo> <mi>A</mi> <mo stretchy="false">|</mo> </mrow> </mfrac> </mfenced> <mrow> <mn>1</mn> <mo>+</mo> <mi>ε</mi> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation> conjugates of either <i>A</i> or <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="493_2025_155_Article_IEq7.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="30" /> </InlineMediaObject> <EquationSource Format="TEX">\(A^{-1}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>A</mi> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> </math></EquationSource> </InlineEquation>. For symmetric sets, this improves on results of Liebeck et al. (2012) and Gill et al. (Groups Geom Dyn 7(4):867–882, 2013). During the preparation of this paper, the proof of the Liebeck–Nikolov–Shalev conjecture was completed by Lifshitz (Completing the proof of the Liebeck–Nikolov–Shalev conjecture, 2024, <a href="https://arxiv.org/abs/2408.10127">https://arxiv.org/abs/2408.10127</a>). Both papers use Gill et al. (Initiating the proof of the Liebeck–Nikolov–Shalev conjecture, 2024, <a href="https://arxiv.org/abs/2408.07800">https://arxiv.org/abs/2408.07800</a>) as a starting point. Lifshitz’s argument uses heavy machinery from representation theory to complete the conjecture, whereas this paper achieves a more modest result by rather elementary combinatorial arguments.</p>

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Writing Finite Simple Groups of Lie Type as Products of Subset Conjugates

  • Daniele Dona

摘要

The Liebeck–Nikolov–Shalev conjecture (Bull Lond Math Soc 44(3):469–472, 2012) asserts that, for any finite simple non-abelian group G and any set \(A\subseteq G\) A G with \(|A|\ge 2\) | A | 2 , G is the product of at most \(N\frac{\log |G|}{\log |A|}\) N log | G | log | A | conjugates of A, for some absolute constant N. For G of Lie type, we prove that for any \(\varepsilon >0\) ε > 0 there is some \(N_{\varepsilon }\) N ε for which G is the product of at most \(N_{\varepsilon }\left( \frac{\log |G|}{\log |A|}\right) ^{1+\varepsilon }\) N ε log | G | log | A | 1 + ε conjugates of either A or \(A^{-1}\) A - 1 . For symmetric sets, this improves on results of Liebeck et al. (2012) and Gill et al. (Groups Geom Dyn 7(4):867–882, 2013). During the preparation of this paper, the proof of the Liebeck–Nikolov–Shalev conjecture was completed by Lifshitz (Completing the proof of the Liebeck–Nikolov–Shalev conjecture, 2024, https://arxiv.org/abs/2408.10127). Both papers use Gill et al. (Initiating the proof of the Liebeck–Nikolov–Shalev conjecture, 2024, https://arxiv.org/abs/2408.07800) as a starting point. Lifshitz’s argument uses heavy machinery from representation theory to complete the conjecture, whereas this paper achieves a more modest result by rather elementary combinatorial arguments.