We prove that the law of a random walk Xn is determined by the
one-dimensional distributions of max(Xn,0) for n=1,2,…, as
conjectured recently by Lo\"ic Chaumont and Ron Doney. Equivalently, the law of
Xn is determined by its upward space-time Wiener-Hopf factor. Our methods
are complex-analytic.Comment: 6 page