Cyclic symmetry loci in Grasssmannians
arXiv:2010.05972
Abstract
The Grassmannian admits an action by a finite cyclic group via the cyclic shift map. We give a simple description of the points fixed by each element of this cyclic group, extending Karp's description of the points fixed by the cyclic shift itself. We give a cell decomposition of the set of totally nonnegative points in each cyclic symmetry locus and describe efficient total positivity tests, extending results of Postnikov to the cyclically symmetric setting. We describe a conjectural generalized cluster structure on cyclic symmetry loci provided the order of the orbifold point is sufficiently large. The generalized exchange relations we find should be a Higher Teichmüller analogue of the relations Chekhov and Shapiro used to study Teichmüller theory of orbifolds.
arXiv comment51 pages, comments welcome
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