Beyond trees: the metric geometry of subsets of weighted Hamming cubes

Associated to any finite metric space are a large number of objects and quantities which provide some degree of structural or geometric information about the space. In this paper we show that in the setting of subsets of weighted Hamming cubes there are unexpected relationships between many of these quantities. We obtain in particular formulas for the determinant of the distance matrix, the M-constant and the cofactor sum for such spaces. This work extends previous results for unweighted metric trees, and more generally, for subsets of standard Hamming cubes, as well as results for weighted metric trees. Finally we consider polygonal equalities in these spaces, giving a complete description of nontrivial 1-polygonal equalities that can arise in weighted Hamming cubes.