Abstract. In this paper, we study the regularity of optimal mappings in Monge's mass transfer problem. Using the approximation to Monge's cost function c(x, y) = |x − y| through the costs c ε (x, y) = ε 2 + |x − y| 2 , we consider the optimal mappings T ε for these costs, and we prove that the eigenvalues of the Jacobian matrix DT ε , which are all positive, are locally uniformly bounded. By an example we prove that T ε is in general not uniformly Lipschitz continuous as ε → 0, even if the mass distributions are positive and smooth, and the domains are c-convex.
IntroductionThe Monge mass transfer problem consists in finding an optimal mapping from one mass distribution to another one such that the total cost is minimized among all measure preserving mappings. This problem was first proposed by Monge [27] and has been studied by many authors in the last two hundred years: among the main achievements in the 20th century we cite [21] and [16].In Monge's problem, the cost of moving a mass from point x to point y is proportional to the distance |x − y|, namely the cost function is given byThis is a natural cost function. In the last two decades, due to a range of applications, the optimal transportation for more general cost functions has been a subject of extensive studies. In order to present the framework more precisely, let Ω and Ω * be two bounded domains in the Euclidean space R n , and let f and g be two densities in Ω and Ω * respectively, satisfying the mass balance conditionLet c be a smooth cost function defined on Ω × Ω * .2010 Mathematics Subject Classification. 35J60, 35B65, 49Q20.