Georges Weil

Cyclical Staff Scheduling Using Constraint Logic Programming

In organizations where duty is around the clock, seven days a week and every week of the year, timetabling is a very difficult task, juggling between the workload and the constraints to be respected. Our work concerns cyclical timetabling. This is not just duplicating a fixed sequence of assignments, but has to consider fixed annual leave, and various regulations on assignments on successive days. In some cases, the cycle sequence has to be relaxed and cycle length shortened or extended. In other cases, a small change in leave dates is allowed, except in summer. This paper describes the context and the use of work cycles in the real world, proposes an abstract model to take into account the various constraints, and finally shows how to implement an effective solution using constraint logic programming (in particular, CHIP V5) to produce timetables of up to 150 people over a yearly horizon.

Analysis of three mathematical models of the Staff Rostering Problem

Staff rostering is a major challenge in the service sector, where exploitation costs are essentially made up of staffing costs. Searching for an optimum has direct economic returns but the rosters must satisfy numerous legal constraints. This paper presents work on an exact approach using branch-and-price methods on a concrete situation. We develop three MILP models and extend them with valid inequalities to two cases. Their computation results on a set of 960 tests covering several scenarios will then be compared and analyzed.

Implementation of a documentation management system for quality assurance in a university hospital.

Development and implementation of guidelines constitutes the basis of quality management systems for any organization. The authors have studied the internal documentation produced by professionals on 88 functional units of a university hospital. Reveals the existence of many documents concerning quality of care with an average of 102 available procedures or protocols per unit. However, this documentation is badly organized, making it difficult to consult and to put into practice. The results of this study were provided to other professionals at our hospital in order to make them aware of the necessity of rigorous document management. We have also written and sent recommendations for drawing up procedures and implementing an efficient documentary management system. This effort complements development of the hospital quality assurance plan.

Decision-support with preference constraints

Abstract One approach to Human Centered Processing is to take into account preferences of users within the context of multiple criteria optimization. The preference model of a problem encloses all the information needed to evaluate the quality of solutions. In this article, we propose a new soft constraint called preference constraint , based on the decision theory concept of binary preference relations. Preference-based constraint systems are defined and a generic algorithm, searching for best quality solutions, is then described. Finally, global constraints, based on a customizable level consistency [G. Verfaillie, D. Martinez, C. Bessiere, A generic customizable framework for inverse local consistency, in: Proc. of the 16th National Conf. on Artificial Intelligence and 11th Conf. on Innovative Applications of Artificial Intelligence, Orlando, Florida], are proposed for solving the preference constraint associated to the Pareto aggregation rule. This new model offers greater flexibility to represent and make complex decisions on computers.

Preference constraints: new global soft constraints dedicated to preference binary relations

The privileged preference representation used for combinatorial problems has been the objective function. It is almost exclusively used at every aggregation levels of a hierarchical preference model, and has remarkable structural properties as transitivity and completeness. These properties are often judged too restrictive, because some important aggregation concepts are incomplete by definition, as efficiency and equity. Moreover, preferences are not necessarily transitive because of uncertainty. For all these reasons, we decided to enlarge objective function-based combinatorial problems toward weaker structured preference concepts: preference binary relations.

Project Planning and Management

Modern information technology is far more than a collection of wires, resistors, chips, plastic, and sheet metal. It is the productive combination of hardware, software, human factors, and environmental factors. Implementing information technology is as much a social process as a technical one. People who are oriented to thinking of technology solely in hardware—or even software—terms have a hard time appreciating the emotional reactions that technological change issues often provoke.