We address the problem of accelerating column generation (CG) for set-covering formulations via dual optimal inequalities (DOIs). study two novel classes DOIs, which are referred to as Flexible DOIs (F-DOIs) and Smooth-DOIs (S-DOIs), respectively (and jointly SF-DOIs). F-DOIs provide rebates covering items more than necessary. S-DOIs describe payment a penalty permit undercoverage in exchange o...

First, we study geometric variants of the standard set cover motivated by assignment of directional antenna and shipping with deadlines, providing the first known polynomial-time exact solutions. Next, we consider the following general (non-necessarily geometric) capacitated set cover problem. There is given a set of elements with real weights and a family of sets of the elements. One can use a...

The phenomenal growth of Internet-based information services and infrastructure in the recent years has provided a new technological basis for enabling and expanding the electronic execution of commercial transactions both on a business-to-business (B2B) and on a business-to-consumer (B2C) level. Electronic Marketplaces have increasingly played the role of an aggregator that merges potentially ...

We consider a network design problem that arises in the costoptimal design of last mile telecommunication networks. It extends the Connected Facility Location problem by introducing capacities on the facilities and links of the networks. It combines aspects of the capacitated network design problem and the single-source capacitated facility location problem We refer to it as the Capacitated Con...

BACKGROUND The majority of established telestroke services are based on "hub-and-spoke" models for providing acute clinical assessment and thrombolysis. We report results from the first year of the successful implementation of a locally based telemedicine network, without the need of 1 or more hub hospitals, across a largely rural landscape. METHODS AND RESULTS Following a successful pilot ph...

The Maximal Covering Location Problem (MCLP) has the objective of maximizing the total demand volume covered by a facility within a maximum allowable travel distance, S. In this paper, three sets of data 30-node, 324-node and 818-node networks with no existing facilities are analyzed as the capacitated model of MCLP (CMCLP) and first solved by the commercial optimization software, CPLEX. As the...

This paper presents an artificial bee colony (ABC) algorithm adjusted for the capacitated vehicle routing problem. The vehicle routing problem is an NP-hard problem and capacitated vehicle routing problem variant (CVRP) is considered here. The artificial bee metaheuristic was successfully used mostly on continuous unconstrained and constrained problems. Here this algorithm has been implemented ...

The BusPlus project aims at improving the off-peak hours public transit service in Canberra, Australia. To address the difficulty of covering a large geographic area, BusPlus proposes a hub and shuttle model consisting of a combination of a few high-frequency bus routes between key hubs and a large number of shuttles that bring passengers from their origin to the closest hub and take them from ...

Extended formulations are now widely used to solve hard combinatorial optimization problems. Such formulations have prohibitively-many variables and are generally solved via Column Generation (CG). CG algorithms are known to have frequent convergence issues, and, up to a sometimes large number of iterations, classical Lagrangian dual bounds may be weak. This paper is devoted to set-covering pro...