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math.CO2026
Grassmannian quantum cohomology in the infinite limit and total positivity
Ines Chung-Halpern, Konstanze Rietsch
The theory of total positivity was shown by Lusztig to be intrinsically linked to the canonical basis with its positivity properties. When we restrict ourselves to studying total p…
math.CO2025
Totally positive Toeplitz matrices: classical and modern
Konstanze Rietsch
By a theorem of Edrei, an infinite, normalised totally nonnegative upper-triangular Toeplitz matrix is determined by a pair of nonnegative parameter sequences, the `Schoenberg para…
math.CO2025
Root polytopes, flow polytopes, and order polytopes
Konstanze Rietsch, Lauren Williams
In this paper we study the class of polytopes which can be obtained by taking the convex hull of some subset of the points in $\ma…