The Chain Matrix of Bouquets of Geometric Lattices and Its Determinant

Abstract This work builds on Varchenko et al.’s introduction of bilinear forms for hyperplane arrangements, where the determinant of the associated matrices factorizes into simple components. While one of the determinant formulas developed by Varchenko has been generalized to complexes of oriented matroids (COMs) already, this question was open for another, distinct form. Motivated by work from Varchenko and Brylawski, who generalized the alternative bilinear form and its determinant formula from hyperplane arrangements to matroids, we examine whether this formula can similarly be generalized to COMs. Our findings affirm this generalization, and we further extend the determinant formula to bouquets of geometric lattices as introduced by Laurent et al.