The algebraic degree of the Wasserstein distance
摘要
Given two rational univariate polynomials, the Wasserstein distance of their associated measures is an algebraic number. We determine the algebraic degree of the squared Wasserstein distance, serving as a measure of algebraic complexity of the corresponding optimization problem. The computation relies on Galois theory and on the combinatorial structure of a specific subpolytope of the Birkhoff polytope, invariant under a transformation induced by complex conjugation. Proofs and computations also draw on notions from graph theory and elimination ideals.