In this paper we characterize the structure of optimal policies for periodic review inventory systems with concave ordering costs. By extending the Scarf (1958) model to systems with piecewise linear concave ordering costs, we show the optimality of generalized (s, S) policies for general demand distributions. We do so by (a) introducing a conditional monotonicity property for the order-up-to l...

We introduce a novel decoding procedure for statistical machine translation and other ordering tasks based on a family of Very Large-Scale Neighborhoods, some of which have previously been applied to other NP-hard permutation problems. We significantly generalize these problems by simultaneously considering three distinct sets of ordering costs. We discuss how these costs might apply to MT, and...

Achieving optimal production cycle time for improving manufacturing processes is one of the common problems in production planning. During recent years, different approaches have been developed for solving this problem, but most of them assume that mean quality characteristic is constant over production run length and sets it on customer’s target value. However, the process mean may drift from ...

In this article, a finite horizon, multi product and multi period economic order quantity like seasonal items is considered where demand rate is deterministic and known but variable in each period. The order quantities of items come in batch sizes and the end of the period order quantity and, consequently, demand of customers are zero. In addition, storage space is constrained and the problem...

OBJECTIVE To determine the costs and cost reductions of an innovative strategy aimed at improving test ordering routines of primary care physicians, compared with a traditional strategy. DESIGN Multicenter randomized controlled trial with randomization at the local primary care physicians group level. SETTING Primary care: local primary care physicians groups in five regions of the Netherla...

We study inventorymanagement problemswhere demands are revealed incrementally and procurement decisionsmust bemade before the demands are realized. There are no probabilistic distributions nor nontrivial bounds to characterize demands. We consider two cost minimization problems: (1) perishable products with lost sales and (2) durable products with backlogged demand. In both problems, costs are ...

The linear ordering problem with cumulative costs (LOPCC) is a variant of the well-known linear ordering problem, in which a cumulative propagation makes the objective function highly non-linear. The LOPCC has been recently introduced in the context of mobile-phone telecommunications. In this paper we propose two metaheuristic methods for this NP-hard problem. The first one is based on the GRAS...

Given a matrix of weights, the Linear Ordering Problem (LOP) consists of finding a permutation of the columns and rows in order to maximize the sum of the weights in the upper triangle. This well known NP-complete problem can also be formulated on a complete weighted graph, where the objective is to find an acyclic tournament that maximizes the sum of arc weights. The variant of the LOP that we...

This paper addresses embedded multiprocessor implementation of iterative, real-time applications, such as digital signal and image processing, that are specified as dataflow graphs. Scheduling dataflow graphs on multiple processors involves assigning tasks to processors (processor assignment), ordering the execution of tasks within each processor (task ordering), and determining when each task ...