oriented-matroids

SageMath package for (chemical) reaction networks using sign vector conditions

SageMath package for sign vectors, oriented matroids and chirotopes

Program that constructs all oriented matroids of the given rank and on the given number of elements.

Applications of SageMath packages dealing with sign and elementary vectors

Lean 4 formalization of infinitely many excluded minors for weakly orientable matroids and the Bland–Jensen conjecture.

A sandbox for experiments with applications of Proposition 5.9 from the monograph A.O. Matveev, Symmetric Cycles, Singapore: Jenny Stanford Publishing, 2023.

A Haskell DistinguishedSymmetricCyclesModule.hs module exporting a few functions that describe a `computation-free' decomposition of a vertex of a hypercube graph with respect to its distinguished symmetric cycle. Based on Proposition 5.9 of the monograph A.O. Matveev, Symmetric Cycles, Jenny Stanford Publishing, 2023.

A simple rank-seven oriented matroid with no simplicial tope, disproving Las Vergnas' simplex conjecture for arbitrary simple oriented matroids