<p>We prove odd analogs of results of Chuang and Rouquier on <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\mathfrak {sl}_2\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="fraktur">sl</mi> <mn>2</mn> </msub> </math></EquationSource> </InlineEquation>-categorification. Combined also with recent work of the second author with Livesey, this allows us to complete the proof of Broué’s Abelian Defect Conjecture for the double covers of symmetric groups. The article also develops the theory of odd symmetric functions initiated a decade ago by Ellis, Khovanov and Lauda. A key role in our approach is played by a 2-category consisting of <i>odd Grassmannian bimodules</i> over superalgebras which are odd analogs of equivariant cohomology algebras of Grassmannians. This is the odd analog of the category of Grassmannian bimodules which was at the heart of Lauda’s independent approach to categorification of <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\mathfrak {sl}_2\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="fraktur">sl</mi> <mn>2</mn> </msub> </math></EquationSource> </InlineEquation>. We also construct an action of the odd Kac-Moody 2-category <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\mathfrak {U}(\mathfrak {sl}_2)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="fraktur">U</mi> <mo stretchy="false">(</mo> <msub> <mi mathvariant="fraktur">sl</mi> <mn>2</mn> </msub> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> on the 2-category of odd Grassmannian bimodules, and use this to give a new proof of its non-degeneracy.</p>

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Odd Grassmannian bimodules and derived equivalences for spin symmetric groups

  • Jonathan Brundan,
  • Alexander Kleshchev

摘要

We prove odd analogs of results of Chuang and Rouquier on \(\mathfrak {sl}_2\) sl 2 -categorification. Combined also with recent work of the second author with Livesey, this allows us to complete the proof of Broué’s Abelian Defect Conjecture for the double covers of symmetric groups. The article also develops the theory of odd symmetric functions initiated a decade ago by Ellis, Khovanov and Lauda. A key role in our approach is played by a 2-category consisting of odd Grassmannian bimodules over superalgebras which are odd analogs of equivariant cohomology algebras of Grassmannians. This is the odd analog of the category of Grassmannian bimodules which was at the heart of Lauda’s independent approach to categorification of \(\mathfrak {sl}_2\) sl 2 . We also construct an action of the odd Kac-Moody 2-category \(\mathfrak {U}(\mathfrak {sl}_2)\) U ( sl 2 ) on the 2-category of odd Grassmannian bimodules, and use this to give a new proof of its non-degeneracy.