Combinatorics of cluster structures in Schubert Varieties

Khrystyna Serhiyenko, Melissa Sherman-Bennett, Lauren Williams

Research output: Contribution to conferencePaperpeer-review


We give an explicit combinatorial description of cluster structures in Schubert varieties of the Grassmannian in terms of (target labelings of) Postnikov's plabic graphs. This description is a natural generalization of the description given by (Scott 2006) for the Grassmannian and has been believed by experts essentially since (Scott 2006), though the statement was not formally written down until (Muller-Speyer 2016). To prove this conjecture we use a result of (Leclerc 2016), who used the module category of the preprojective algebra to prove that coordinate rings of many Richardson varieties in the complete flag variety admit cluster structures. We also adapt a construction of (Karpman 2016) to build cluster seeds associated to reduced expressions. Further, we explicitly describe cluster structures in skew Schubert varieties using plabic graphs whose boundary vertices need not be labeled in cyclic order.

Original languageEnglish
StatePublished - 2019
Event31st International Conference on Formal Power Series and Algebraic Combinatorics, FPSAC 2019 - Ljubljana, Slovenia
Duration: Jul 1 2019Jul 5 2019


Conference31st International Conference on Formal Power Series and Algebraic Combinatorics, FPSAC 2019

Bibliographical note

Funding Information:
We are grateful to Bernard Leclerc for numerous helpful discussions. K.S. and M.S.B. acknowledge support from National Science Foundation Postdoctoral Fellowship MSPRF-1502881 and NSF Graduate Research Fellowship No. DGE-1752814, respectively. L. W. was partially supported by the NSF grant DMS-1600447. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

Publisher Copyright:
© FPSAC 2019 - 31st International Conference on Formal Power Series and Algebraic Combinatorics. All rights reserved.


  • Cluster algebra
  • Plabic graph
  • Positroid
  • Schubert variety

ASJC Scopus subject areas

  • Algebra and Number Theory


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