WorldCat Identities

Demassey, Sophie

Works: 5 works in 19 publications in 2 languages and 301 library holdings
Roles: Editor, Author
Publication Timeline
Most widely held works by Sophie Demassey
Resource-constrained project scheduling : models, algorithms, extensions and applications by Christian Artigues( )

13 editions published between 2008 and 2013 in English and held by 293 WorldCat member libraries worldwide

"This title presents a large variety of models and algorithms dedicated to solving one of the most important problems in project rnanaqement, manufacturing and resource optimization; the resource-constrained project scheduling problem (RCPSP)r which aims to schedule at minimal duration a set of activities subject to precedence constraints and the limited availability of resources."--Jacket
Méthodes hybrides de programmation par contraintes et programmation linéaire pour le problème d'ordonnancement de projet à contrainte de ressources by Sophie Demassey( )

2 editions published between 2003 and 2008 in French and held by 3 WorldCat member libraries worldwide

The standard resource-constrained project scheduling problem (RCPSP) aims at scheduling the activities of a project sharing renewelable resources, available in limited amounts. The intractability of the RCPSP has motivated test of numerous optimization techniques and led to an extensive literature.We are interested in the exact resolution of this problem by means of methods combining constraint programming (CP) and linear programming (LP) techniques.Such hybrid methods are more and more successfully applied to solve the hardest combinatorial problems. This dissertation opens with a review of the main CP/LP hybrid exact methods in the optimization literature, and a state-of-the-art for the RCPSP.In a first part, we present new lower bounds for the RCPSP computed by lagrangean relaxation and cutting-plane generation techniques.Well-known constraint propagation techniques as well as a new shaving scheme are applied as preprocessing to speed up the resolution of the different linear programs. Furthermore, we present original cutting planes for the RCPSP that are directly derived from the deductions of the constraint propagation phase . Our experiments show that these lower bounds are among the best lower bounds known to date for the RCPSP.In the second part, we propose an original exact method for the RCPSP, based on the resolution search algorithm of Chvatal. We present a study of this algorithm which is an alternative to the branch-and-bound methods. We also show how resolution search can be assimilated to intelligent backtracking in constraint programming.We prove its efficiency by an experimental comparison with a similar branch-and-bound for the RCPSP.Last, we introduce some new features to improve the general algorithm or to adapt it more specifically to the RCPSP
Multi-Agent Electro-Location and the "Among" Constraint by Institut national de recherche en informatique et en automatique (France)( )

1 edition published in 2011 in English and held by 1 WorldCat member library worldwide

In this paper, we give a new approach for the localization of several autonomous fish robots equipped with the electric sense. The approach is based on interval arithmetic and constraint programming. It introduces a generalization of the Among constraint which was used so far in the different context of resource allocation in logistics. We prove that the bound consistency for a conjunction of Among constraints with interval domains is NP-complete in the vector case and polynomial in the one-dimensional case. Although it was designed for electric fish robots, this work is not restricted to this type of systems. The approach can be easily extended to other multi-agent systems with low-range sensing
Resource-constrained project scheduling models, algorithms, extensions and applications( )

in English and held by 1 WorldCat member library worldwide

Constraint programming based column generation for employee timetabling by International Conference on Integration of AI and OR Techniques in Constraint Programming for Combinatorial Optimization( )

1 edition published in 2008 in English and held by 1 WorldCat member library worldwide

The Employee Timetabling Problem (ETP) is a general class of problems widely encountered in service organizations (such as call centers for instance). Given a set of activities, a set of demand curves (specifying the demand in terms of employees for each activity for each time period) the problem consists of constructing a set of work shifts such that each activity is at all time covered by a sufficient number of employees. Work shifts can cover many activities and must meet work regulations such as breaks, meals and maximum working time constraints. Furthermore, it is often desired to optimize a global objective function such as minimizing labor costs or maximizing a quality of service measure. This paper presents variants of this problem which are modeled with the Dantzig formulation. This approach consists of first generating all feasible work shifts and then selecting the optimal set. We propose to address the shift generation problem with constraint satisfaction techniques based on expressive and efficient global constraints such as GCC and REGULAR. The selection problem, which is modeled with an integer linear program, is solved by a standard MIP solver for smaller instances and addressed by column generation for larger ones. Since a column generation procedure needs to generate only shifts of negative reduced cost, the optimization constraint COST-REGULAR is introduced and described. Preliminary experimental results are given on a typical ETP
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Audience Level
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Audience level: 0.60 (from 0.59 for Resource-c ... to 0.99 for Multi-Agen ...)

Associated Subjects
Resource-constrained project scheduling : models, algorithms, extensions and applications
Resource-constrained project scheduling models, algorithms, extensions and applications
English (16)

French (2)