We present improved combinatorial approximation algorithms for the uncapacitated facility location and k-median problems. Two central ideas in most of our results are cost scaling and greedy improvement. We present a simple greedy local search algorithm which achieves an approximation ratio of 2:414+ in ~ O(n= ) time. This also yields a bicriteria approximation tradeo of (1+ ; 1+ 2= ) for facil...

In the classical k-median problem the goal is to select a subset of at most k facilities in order to minimize the total cost of opened facilities and established connections between clients and opened facilities. We consider the capacitated version of the problem, where a single facility may only serve a limited number of clients. We construct approximation algorithms slightly violating the cap...

In this paper we tackle a two-echelon location-routing problem (2E-LRP) by a tabu search metaheuristic. The aim is to define the location and number of two kinds of capacitated facilities, the size of two different vehicle fleets and the related routes on each echelon. The proposed Tabu Search (TS) for the 2E-LRP is based on the decomposition of the problem in two location-routing sub-problems,...

Abstract The warehousing logistics mode of “pre-warehouse plus terminal distribution” is a decentralized resource allocation scheme around the industry at end distribution, supporting development New Retail, data-driven extensive retail form centered on consumer experience. Firstly, taking stand-alone pre-warehouse as research object, this paper analyzed distribution characteristics new fresh g...

In this work, the capacitated location-routing problem with simultaneous pickup and delivery (CLRP-SPD) is considered. This problem is a more realistic case of the capacitated location-routing problem (CLRP) and belongs to the reverse logistics of the supply chain. The problem has many real-life applications of which some have been addressed in the literature such as management of liquid petrol...

The general facility location problem and its variants, including most location-allocation and P-median problems, are known to be NP-hard combinatorial optimization problems. Consequently , there is now a substantial body of literature on heuristic algorithms for a variety of location problems, among which can be found several versions of the well-known simulated annealing algorithm. This paper...

We consider the robust single-source capacitated facility location problem with uncertainty in customer demands. A cardinality-constrained set is assumed for problem. To solve it efficiently, we propose an allocation-based formulation derived by Dantzig–Wolfe decomposition and a branch-and-price algorithm. The computational experiments show that our algorithm outperforms CPLEX many cases, which...

Counting-based branching heuristics in CP have been very successful on a number of problems. Among the few remaining hurdles limiting their general applicability are the integration of counting information from auxiliary variables and the ability to handle combinatorial optimization problems. This paper proposes to answer these challenges by generalizing existing solution counting algorithms fo...

In the two-stage capacitated facility location problem a single product is produced at some plants in order to satisfy customer demands. The product is transported from these plants to some depots and then to the customers. The capacities of the plants and depots are limited. The aim is to select cost minimizing locations from a set of potential plants and depots. This cost includes fixed cost ...