We prove that the sufficiency condition employed to show the existence and, in certain cases the uniqueness, of solutions to the discrete, planar L 0 -Minkowski problem with data containing, at least, a pair of opposite vectors is also a necessary condition. (2000): 28A75, 52A10.
Mathematics Subject ClassificationThe classical Minkowski problem deals with the existence, uniqueness, regularity and stability of closed, convex hypersurfaces whose Gauss curvature, viewed as a function on the unit sphere, is preassigned. For an atomic measure on the unit sphere, the question concerns the existence and uniqueness of polytopes with facets of fixed normal directions and fixed surface areas. In the planar setting, the Minkowski problem consists of a sufficient and necessary condition for the existence of a convex polygon whose sides have preassigned lengths and orientations:an ordered set of directions in S 1 , not all in a half-disk, and let L = {l 1 , ..., l N } be an ordered set of strictly positive numbers. There exists a convex N-gon whose i-th side has outer normal → u i and, respectively, length l i if and only ifThis is the simplest and the trivial case of Minkowski's problem as the aforementioned condition represents simply the closure of a polygonal line with the desired properties. One should note that the convex polygon so obtained is unique up to translation. See [16] for a detailed discussion on the full extent of Minkowski's problem.Due to Lutwak [10], a significantly more difficult question is whether a measure on the unit sphere S n can be realized as the L p -surface area measure of a convex body, where p = n is some fixed real number. If so, is this body unique? Lutwak showed within the Brunn-Minkowski-Firey theory that the classical problem, corresponding to p = 1, generalizes naturally to the L p -Minkowski problem stated above. In [10] a solution to the even L p -Minkowski problem in R n+1 was given for all p ≥ 1 except for p = n when it was shown that no solution is possible. The problem is called even if the measure takes equal values on opposite directions of S n . It is conjectured that in the even case the convex body, if it exists, is centrally symmetric, [10].162