2 papers
math.CO2025
Positroid envelopes and graphic positroids
Jeremy Quail, Puck Rombach
Positroids are matroids realizable by real matrices with all nonnegative maximal minors. They partition the ordered matroids into equivalence classes, called positroid envelope cla…
math.CO2024
Ternary and quaternary positroids
Jeremy Quail
A positroid is an ordered matroid realizable by a real matrix with all nonnegative maximal minors. Postnikov gave a map from ordered matroids to Grassmann necklaces, for which ther…