Singularities of Schubert Varieties within a Right Cell

We describe an algorithm that pattern embeds, in the sense of Woo-Yong, any Bruhat interval of a symmetric group into an interval whose extremes lie in the same right Kazhdan-Lusztig cell. This apparently harmless fact has applications in finding examples of reducible associated varieties of ₙ-highe...

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Опубліковано в: :Symmetry, Integrability and Geometry: Methods and Applications
Дата:2021
Автори: Lanini, Martina, McNamara, Peter J.
Формат: Стаття
Мова:Англійська
Опубліковано: Інститут математики НАН України 2021
Онлайн доступ:https://nasplib.isofts.kiev.ua/handle/123456789/211353
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Назва журналу:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Цитувати:Singularities of Schubert Varieties within a Right Cell. Martina Lanini and Peter J. McNamara. SIGMA 17 (2021), 070, 9 pages

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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author Lanini, Martina
McNamara, Peter J.
author_facet Lanini, Martina
McNamara, Peter J.
citation_txt Singularities of Schubert Varieties within a Right Cell. Martina Lanini and Peter J. McNamara. SIGMA 17 (2021), 070, 9 pages
collection DSpace DC
container_title Symmetry, Integrability and Geometry: Methods and Applications
description We describe an algorithm that pattern embeds, in the sense of Woo-Yong, any Bruhat interval of a symmetric group into an interval whose extremes lie in the same right Kazhdan-Lusztig cell. This apparently harmless fact has applications in finding examples of reducible associated varieties of ₙ-highest weight modules, as well as in the study of W-graphs for symmetric groups, and in comparing various bases of irreducible representations of the symmetric group or its Hecke algebra. For example, we can systematically produce many negative answers to a question from the 1980s of Borho-Brylinski and Joseph, which had been settled by Williamson via computer calculations only in 2014.
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publisher Інститут математики НАН України
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spelling Lanini, Martina
McNamara, Peter J.
2025-12-30T15:54:15Z
2021
Singularities of Schubert Varieties within a Right Cell. Martina Lanini and Peter J. McNamara. SIGMA 17 (2021), 070, 9 pages
1815-0659
2020 Mathematics Subject Classification: 14M15; 20B30; 32C38; 20C08
arXiv:2003.08616
https://nasplib.isofts.kiev.ua/handle/123456789/211353
https://doi.org/10.3842/SIGMA.2021.070
We describe an algorithm that pattern embeds, in the sense of Woo-Yong, any Bruhat interval of a symmetric group into an interval whose extremes lie in the same right Kazhdan-Lusztig cell. This apparently harmless fact has applications in finding examples of reducible associated varieties of ₙ-highest weight modules, as well as in the study of W-graphs for symmetric groups, and in comparing various bases of irreducible representations of the symmetric group or its Hecke algebra. For example, we can systematically produce many negative answers to a question from the 1980s of Borho-Brylinski and Joseph, which had been settled by Williamson via computer calculations only in 2014.
The authors would like to thank the Institut Henri Poincaré in Paris and the organisers of the Representation Theory Trimester. M.L. acknowledges the MIUR Excellence Department Project awarded to the Department of Mathematics, University of Rome Tor Vergata, CUP E83C18000100006, and the PRIN2017 CUP E8419000480006. P.M. acknowledges support from ARC grants DE150101415 and DP180103150. We thank G. Williamson for useful conversations and the anonymous referees for their valuable input.
en
Інститут математики НАН України
Symmetry, Integrability and Geometry: Methods and Applications
Singularities of Schubert Varieties within a Right Cell
Article
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spellingShingle Singularities of Schubert Varieties within a Right Cell
Lanini, Martina
McNamara, Peter J.
title Singularities of Schubert Varieties within a Right Cell
title_full Singularities of Schubert Varieties within a Right Cell
title_fullStr Singularities of Schubert Varieties within a Right Cell
title_full_unstemmed Singularities of Schubert Varieties within a Right Cell
title_short Singularities of Schubert Varieties within a Right Cell
title_sort singularities of schubert varieties within a right cell
url https://nasplib.isofts.kiev.ua/handle/123456789/211353
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AT mcnamarapeterj singularitiesofschubertvarietieswithinarightcell