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math.CO2021
Positroids are 3-colorable
Lamar Chidiac, Winfried Hochstättler
We show that every positroid of rank has a good coline. Using the definition of the chromatic number of oriented matroid introduced by J.\ Nešetřil, R.\ Nickel, and W.~H…
math.CO2021
Independent Hyperplanes in Oriented Paving Matroids
Lamar Chidiac, Winfried Hochstättler
In 1993, Csima and Sawyer proved that in a non-pencil arrangement of n pseudolines, there are at least simple points of intersection. Since pseudoline arrangements…