In this article we focus on approximation algorithms for facility location problems with subadditive costs. As examples of such problems, we present two facility location problems with stochastic demand and exponential servers, respectively inventory. We present a (1 + , 1)-reduction of the facility location problem with subadditive costs to a soft capacitated facility location problem, which i...

In this paper, we consider the problem of “importance sampling” from a high dynamic range image motivated by a computer graphics problem called image-based lighting. Image-based lighting is a method to light a scene by using real-world images as part of a 3D environment. Intuitively, the sampling problem reduces to finding representative points from the image such that they are in higher densit...

The major oil industry upstream activities include the exploration, drilling, extraction, pipelines installation, and production of crude oil. In this paper, we develop a mathematical model to plan for theseoperations as a crude oil supply chain network design problem.The proposed multi-period mixed integer linear programming model entails both strategic (e.g., facility location and allocation)...

The k-facility location problem is a common generalization of the facility location and the k-median problems. For the metric uncapacitated k-facility location problem, we propose a polynomial-time 2 + √ 3 + ǫ-approximation algorithm using the local search approach, which significantly improves the previously known approximation ratio 4, given by Jain et al. using the greedy method (J. ACM 50 (...