3 papers
math.CO2026
On the Possibilities of Defining Infinite Oriented Matroids
Nathan Bowler, Winfried Hochstättler, Stefan Kaspar
Is it possible to define cryptomorphic axiom systems for infinite oriented matroids by lifting some of the axiom systems for finite oriented matroids to the infinite setting while…
math.CO2021
A Trivariate Dichromate Polynomial for Digraphs
Winfried Hochstättler, Johanna Wiehe
We define a trivariate polynomial combining the NL-coflow and the NL-flow polynomial, which build a dual pair counting acyclic colorings of directed graphs, in the more general set…
math.CO2019
The Chromatic Polynomial of a Digraph
Winfried Hochstättler, Johanna Wiehe
An acyclic coloring of a digraph as defined by Neumann-Lara is a vertex-coloring such that no monochromatic directed cycles occur. Counting the number of such colorings with co…