David E Speyer

activity

20242026

collaborators

3 papers

math.CO2026

L-log-concavity and a proof of the conjecture of Lam, Postnikov and Pylyavskyy

David E Speyer

Let $λ$ , $μ$ , $λ^{'}$ , $μ^{'}$ be partitions. The conjecture of Lam, Postnikov and Pylyavskyy states that, if $λ + μ = λ^{'} + μ^{'}$ , and $\min(λ_i-λ_j, μ_i-μ_j) \leq λ'_i - λ'_j \leq \max(λ_i-λ…

math.CO2025

Rowmotion and Echelonmotion

Colin Defant, Yuhan Jiang, Rene Marczinzik +4

Given a linear extension $σ$ of a finite poset $R$ , we consider the permutation matrix indexing the Schubert cell containing the Cartan matrix of $R$ with respect to $σ$ . This yiel…

math.CO2024

The omega invariant of a matroid

Alex Fink, Kris Shaw, David E Speyer

The third author introduced the $g$ -polynomial $g_{M} (t)$ of a matroid, a covaluative matroid statistic which is unchanged under series and parallel extension. The $g$ -polynomial of…