<p>Let <i>X</i> be a rational surface obtained by blowing up at a configuration <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13398_2025_1758_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="22" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathscr {C}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="script">C</mi> </math></EquationSource> </InlineEquation> of infinitely near points over a Hirzebruch surface <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13398_2025_1758_Article_IEq2.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathbb {F}_\delta \)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="double-struck">F</mi> <mi>δ</mi> </msub> </math></EquationSource> </InlineEquation>. We prove that there exist two positive integers <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13398_2025_1758_Article_IEq3.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="44" /> </InlineMediaObject> <EquationSource Format="TEX">\(a \le b\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>a</mi> <mo>≤</mo> <mi>b</mi> </mrow> </math></EquationSource> </InlineEquation> such that the cone of curves of <i>X</i> is finite polyhedral and minimally generated when <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13398_2025_1758_Article_IEq4.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="43" /> </InlineMediaObject> <EquationSource Format="TEX">\(\delta \ge a\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>δ</mi> <mo>≥</mo> <mi>a</mi> </mrow> </math></EquationSource> </InlineEquation>, and the Cox ring of <i>X</i> is finitely generated whenever <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13398_2025_1758_Article_IEq5.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="43" /> </InlineMediaObject> <EquationSource Format="TEX">\(\delta \ge b\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>δ</mi> <mo>≥</mo> <mi>b</mi> </mrow> </math></EquationSource> </InlineEquation>. The integers <i>a</i> and <i>b</i> depend only on a combinatorial object (a graph decorated with arrows) representing the strict transforms of the exceptional divisors, their intersections and those with the fibers and special section of <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13398_2025_1758_Article_IEq2.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathbb {F}_\delta \)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="double-struck">F</mi> <mi>δ</mi> </msub> </math></EquationSource> </InlineEquation>.</p>

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The cone of curves and the Cox ring of rational surfaces over Hirzebruch surfaces

  • Carlos Galindo,
  • Francisco Monserrat,
  • Carlos-Jesús Moreno-Ávila

摘要

Let X be a rational surface obtained by blowing up at a configuration \(\mathscr {C}\) C of infinitely near points over a Hirzebruch surface \(\mathbb {F}_\delta \) F δ . We prove that there exist two positive integers \(a \le b\) a b such that the cone of curves of X is finite polyhedral and minimally generated when \(\delta \ge a\) δ a , and the Cox ring of X is finitely generated whenever \(\delta \ge b\) δ b . The integers a and b depend only on a combinatorial object (a graph decorated with arrows) representing the strict transforms of the exceptional divisors, their intersections and those with the fibers and special section of \(\mathbb {F}_\delta \) F δ .