Sparsity-Constrained Transportation Problem
  We study the solution of a large-scale transportation problem with an additional constraint on the sparsity of inbound flows. Such problems arise in the management of inventory for online retailers that operate with many order fulfillment centers; each stock-keeping unit is typically kept in a limited number of these order fulfillment centers so as to reduce the operational overhead in the supply chain network.   We propose a computationally efficient algorithm that solves this sparsity-constrained optimization problem while bypassing complexities of the conventional integer programming approach. The effectiveness of the algorithm is demonstrated through a series of numerical experiments on synthetic data. 
Annie I. Chen and Stephen C. Graves
math.OC