We consider the maximum feasible subsystem problem in which, given an infeasible system of linear inequalities, one wishes to determine a largest feasible subsystem. The focus is on the version with bounded variables that naturally arises in several fields of application. To tackle this NP-hard problem, we propose a simple but efficient two-phase relaxation-based heuristic. First a feasible sub...

Delivery companies are offering an increasing number of time-definite services. Yet, little research has been done that explores the design of delivery networks and accounts for these time-definite services. In this paper, we explore such design problems for networks with a specified number of edges B > n − 1. We present a two-phase heuristic solution approach that first constructs a network an...

We propose a two-phase heuristic for crossing reduction in circular layouts. While the first algorithm uses a greedy policy to build a good initial layout, an adaptation of the sifting heuristic for crossing reduction in layered layouts is used for local optimization in the second phase. Both phases are conceptually simpler than previous heuristics, and our extensive experimental results indica...

This paper addresses a one-machine scheduling problem in which the efficiency of the machine is not constant, that is the duration of a task is longer in badly efficient time periods. Each task has an irregular completion cost. Under the assumption that the efficiency constraints are time-periodic, we show that the special case where the sequence is fixed can be solved in polynomial time. The g...

This paper introduces a shift rostering problem that surprisingly has not been studied in literature: the weekend shift rostering problem. It is motivated by our experience that employees’ shift preferences predominantly focus on the weekends, since many social activities happen during weekends. The Weekend Rostering Problem (WRP) addresses the rostering of weekend shifts, for which we design a...

This paper presents a methodology for solving the Periodic Vehicle Routing Problem (PVRP). Customer locations each with a certain daily demand are known, as well as the capacity of vehicles. In this work, the problem is solved by means of a two-phase heuristic. The first phase is the itinerary assignment to visit each customer, and in the second phase the routing is done for each day of the iti...

In automated float glass manufacturing, a continuous ribbon of glass is cut according to customer orders and then offloaded using robots. We consider the problem of laying out and sequencing the orders on the ribbon so as to minimize waste. The problem combines characteristics of cutting, packing, and sequencing problems. Given the size and the complexity of the problem, we propose a two-phase ...

Examination timetabling problems are often solved by a two-phase procedure combining a sequential construction heuristic with a metaheuristic improvement search. There can be many combinations of pairing candidate construction heuristics with a metaheuristic. Different pairings are known to produce solutions of varying quality. In this paper we propose a Case Based Reasoning methodology for sel...

We consider the following problem: to decompose a nonnegative integer matrix into a linear combination of binary matrices that respect the consecutive ones property. This problem occurs in the radiotherapy treatment of cancer. The nonnegative integer matrix corresponds to fields giving the different radiation beams that a linear accelerator has to send throughout the body of a patient. Due to t...

Motivated by a strongly growing interest in anonymizing social network data, we investigate the NP-hard Degree Anonymization problem: given an undirected graph, the task is to add a minimum number of edges such that the graph becomes k-anonymous. That is, for each vertex there have to be at least k − 1 other vertices of exactly the same degree. The model of degree anonymization has been introdu...