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The Green Ring of a Restricted Enveloping Algebra in Characteristic 2

Aug 2026 · Algebras and Representation Theory · 0 citations · 10 references

Abstract

<jats:p> Let <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\Bbbk $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>k</mml:mi> </mml:math> </jats:alternatives> </jats:inline-formula> be an algebraically closed field of characteristic 2 and let <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\mathfrak {fsl}(2)$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>fsl</mml:mi> <mml:mo>(</mml:mo> <mml:mn>2</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> be the unique, up to isomorphism, 3-dimensional simple Lie algebra over <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\Bbbk $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>k</mml:mi> </mml:math> </jats:alternatives> </jats:inline-formula> . Denote by <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\mathfrak {m}$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>m</mml:mi> </mml:math> </jats:alternatives> </jats:inline-formula> the minimal 2-envelope of <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\mathfrak {fsl}(2)$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>fsl</mml:mi> <mml:mo>(</mml:mo> <mml:mn>2</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> and by <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\mathfrak {u}(\mathfrak {m})$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>u</mml:mi> <mml:mo>(</mml:mo> <mml:mi>m</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> its corresponding restricted enveloping algebra. The non-isomorphic finite-dimensional indecomposable <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\mathfrak {u}(\mathfrak {m})$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>u</mml:mi> <mml:mo>(</mml:mo> <mml:mi>m</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> -modules were classified in [1]. In this paper, the Green ring (or representation ring) for <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\mathfrak {u}(\mathfrak {m})$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>u</mml:mi> <mml:mo>(</mml:mo> <mml:mi>m</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> is calculated. Also, the semisimplification of the representation category of <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\mathfrak {u}(\mathfrak {m})$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>u</mml:mi> <mml:mo>(</mml:mo> <mml:mi>m</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> is determined. </jats:p>

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Janaine Martins, Rosa M. Miró-Roig · 0 citations
Open access Nov 2025

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The residue of this product of poles is a theory-dependent (so non-universal) function of <jats:inline-formula> <jats:alternatives> <jats:tex-math>\beta</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>β</mml:mi> </mml:math> </jats:alternatives> </jats:inline-formula> and the fixed angular velocities. The inverse Laplace transformation of this partition function constrains the functional form of the field theory entropy as a function of charges in a limit in which angular momenta and the twist are scaled as follows. 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H. Anand, N. Benjamin, Vipul Kumar et al. · 8 citations · ⚡3
Open access Aug 2026

Non-Abelian Amplification and Bilinear Forms with Kloosterman Sums

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Alexandru Pascadi · 0 citations
Open access Sep 2025

Fusion in the periodic Temperley–Lieb algebra: General definition of a bifunctor

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Y. Ikhlef, Alexi Morin-Duchesne · 2 citations
Open access Jul 2026

Infinite Sidon-type sets for zero-sum linear forms

<jats:p> Let <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$h \ge 2$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>h</mml:mi> <mml:mo>≥</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> , and let <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\textbf{b} = (b_1,\dots ,b_h)\in \mathbb {Z}^h$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>b</mml:mi> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:msub> <mml:mi>b</mml:mi> <mml:mn>1</mml:mn> </mml:msub> <mml:mo>,</mml:mo> <mml:mo>⋯</mml:mo> <mml:mo>,</mml:mo> <mml:msub> <mml:mi>b</mml:mi> <mml:mi>h</mml:mi> </mml:msub> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>∈</mml:mo> <mml:msup> <mml:mrow> <mml:mi>Z</mml:mi> </mml:mrow> <mml:mi>h</mml:mi> </mml:msup> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> be a zero-sum vector with nonzero coordinates. For a set <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$A=\{a_1<a_2<\cdots \}\subseteq \mathbb {N}$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>A</mml:mi> <mml:mo>=</mml:mo> <mml:mo>{</mml:mo> <mml:msub> <mml:mi>a</mml:mi> <mml:mn>1</mml:mn> </mml:msub> <mml:mo><</mml:mo> <mml:msub> <mml:mi>a</mml:mi> <mml:mn>2</mml:mn> </mml:msub> <mml:mo><</mml:mo> <mml:mo>⋯</mml:mo> <mml:mo>}</mml:mo> <mml:mo>⊆</mml:mo> <mml:mi>N</mml:mi> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> , let <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$r_{A,\textbf{b}}(n)$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>r</mml:mi> <mml:mrow> <mml:mi>A</mml:mi> <mml:mo>,</mml:mo> <mml:mi>b</mml:mi> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>n</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> denote the number of <jats:italic>h</jats:italic> -tuples <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$(x_1,\ldots ,x_h)$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>(</mml:mo> <mml:msub> <mml:mi>x</mml:mi> <mml:mn>1</mml:mn> </mml:msub> <mml:mo>,</mml:mo> <mml:mo>…</mml:mo> <mml:mo>,</mml:mo> <mml:msub> <mml:mi>x</mml:mi> <mml:mi>h</mml:mi> </mml:msub> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> of pairwise distinct elements of <jats:italic>A</jats:italic> satisfying <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$b_1x_1+\cdots +b_hx_h=n$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>b</mml:mi> <mml:mn>1</mml:mn> </mml:msub> <mml:msub> <mml:mi>x</mml:mi> <mml:mn>1</mml:mn> </mml:msub> <mml:mo>+</mml:mo> <mml:mo>⋯</mml:mo> <mml:mo>+</mml:mo> <mml:msub> <mml:mi>b</mml:mi> <mml:mi>h</mml:mi> </mml:msub> <mml:msub> <mml:mi>x</mml:mi> <mml:mi>h</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mi>n</mml:mi> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> . We study density restrictions on sets <jats:italic>A</jats:italic> for which these representation counts remain small, obtaining analogues of the classical density theorem for infinite Sidon sets. In the case <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\textbf{b} = (c_1,-c_1,\dots ,c_k,-c_k)$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>b</mml:mi> <mml:mo>=</mml:mo> <mml:mo>(</mml:mo> <mml:msub> <mml:mi>c</mml:mi> <mml:mn>1</mml:mn> </mml:msub> <mml:mo>,</mml:mo> <mml:mo>-</mml:mo> <mml:msub> <mml:mi>c</mml:mi> <mml:mn>1</mml:mn> </mml:msub> <mml:mo>,</mml:mo> <mml:mo>⋯</mml:mo> <mml:mo>,</mml:mo> <mml:msub> <mml:mi>c</mml:mi> <mml:mi>k</mml:mi> </mml:msub> <mml:mo>,</mml:mo> <mml:mo>-</mml:mo> <mml:msub> <mml:mi>c</mml:mi> <mml:mi>k</mml:mi> </mml:msub> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> , we prove that if <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$A(x)/(x/\log x)^{1/2k}\rightarrow \infty $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>A</mml:mi> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>x</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>/</mml:mo> <mml:msup> <mml:mrow> <m

Christian Táfula · 0 citations
Open access Jul 2026

Generalized $$\mathcal {W}$$-Gorenstein Modules

<jats:p> In this paper, we introduce the notion of generalized <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\mathcal {W}$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>W</mml:mi> </mml:math> </jats:alternatives> </jats:inline-formula> -Gorenstein modules respect to some subclass <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\mathcal {W}$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>W</mml:mi> </mml:math> </jats:alternatives> </jats:inline-formula> , extending the classical notion of Gorenstein projective modules. By exploiting the correspondence between projective modules over the endomorphism ring <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\textrm{End}_R(C)$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>End</mml:mtext> <mml:mi>R</mml:mi> </mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>C</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> of a module <jats:italic>C</jats:italic> and elements of its additive closure <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\mathcal {W}=\textrm{Add}_R(C)$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>W</mml:mi> <mml:mo>=</mml:mo> <mml:msub> <mml:mtext>Add</mml:mtext> <mml:mi>R</mml:mi> </mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>C</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> , we establish a fundamental correspondence between Gorenstein projective <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\textrm{End}_R(C)$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>End</mml:mtext> <mml:mi>R</mml:mi> </mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>C</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> -modules and generalized <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\textrm{Add}_R(C)$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>Add</mml:mtext> <mml:mi>R</mml:mi> </mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>C</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> -Gorenstein modules. This result refines existing relative homological settings and provides a natural extension of well-known results in Gorenstein homological algebra. We explore key properties, such as closure under direct summands and sums, and identify conditions under which the class of generalized <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\mathcal {W}$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>W</mml:mi> </mml:math> </jats:alternatives> </jats:inline-formula> -Gorenstein modules coincides with other classes of modules, like Gorenstein projective modules. </jats:p>

Driss Bennis, C. Lomp, Abderrazak Nassir · 0 citations

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