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Ph.D de

Group : Learning and Optimization

Adaptive operator selection in evolutionary algorithms

Starts on 10/10/2007
Advisor : SCHOENAUER, Marc

Funding : CDD sur contrat INRIA
Affiliation : Université Paris-Sud
Laboratory : LRI AO

Defended on 22/12/2010, committee :
- Agoston E. Eiben (rapporteur), Vrije Universiteit Amsterdam, Pays-Bas
- Youssef Hamadi, Microsoft Research Cambridge, Royaume-Uni
- Yannis Manoussakis, Université Paris-Sud XI
- Marc Schoenauer (directeur de thèse), INRIA Saclay
- Michele Sebag (directrice de thèse), CNRS/LRI
- Thomas Stuetzle (rapporteur), FNRS/IRIDIA, Bruxelles, Belgique
- Dirk Thierens, Universiteit Utrecht, Pays-Bas

Research activities :

Abstract :
Evolutionary Algorithms (EAs) are stochastic optimization algorithms which
have already shown their efficiency on many application domains. This is
achieved mainly due to the many parameters that can be defined by the user
according to the problem at hand. However, the performance of EAs is very
sensitive to the setting of these parameters, and there are no general
guidelines for an efficient setting; as a consequence, EAs are rarely used
by researchers from domains other than computer science. The
methodsproposed in this thesis contribute towards alleviating the user
from theneed of defining two very sensitive and problem-dependent choices:
whichvariation operators should be used for the generation of new
solutions, and at which rate each operator should be applied. The
paradigm, referredto as Adaptive Operator Selection (AOS), provides the
on-line autonomouscontrol of the operator that should be applied at each
instant of the search, i.e., while solving the problem. In order to do so,
one needs to define a Credit Assignment scheme, which rewards the
operators based on theimpact of their recent applications on the current
search process, and an Operator Selection mechanism, that decides which
should be the next operator to be applied, based on the empirical quality
estimates built by the rewards received. In this work, we have tackled the
Operator Selection problem as an instance of the Exploration versus
Exploitation dilemma: the best operator needs to be exploited as much as
possible, while the others should also be minimally explored from time to
time, as one of them might become the best in a further moment of the
search. We have proposed different Operator Selection techniques to extend
the Multi-Armed Bandit paradigm to the dynamic context of AOS. On the
Credit Assignment side, we have proposed rewarding schemes based on
extreme values and on ranks, in order to promote the use of outlier
operators, while providing more robust operator assessments. The different
AOS methods formed by the combinations of the proposed Operator Selection
and Credit Assignment mechanisms have been validated on a very diverse set
of benchmark problems. Based on empirical evidence gathered from this
empirical analysis, the final recommended method, which uses the
Rank-based Multi-Armed Bandit Operator Selection and the Area-Under-Curve
Credit Assignment schemes, has been shown to achieve state-of-the-art
performance while also being very robust withrespect to different

Ph.D. dissertations & Faculty habilitations
The original manuscript conceptualizes the recent rise of digital platforms along three main dimensions: their nature of coordination devices fueled by data, the ensuing transformations of labor, and the accompanying promises of societal innovation. The overall ambition is to unpack the coordination role of the platform and where it stands in the horizon of the classical firm – market duality. It is also to precisely understand how it uses data to do so, where it drives labor, and how it accommodates socially innovative projects. I extend this analysis to show continuity between today’s society dominated by platforms and the “organizational society”, claiming that platforms are organized structures that distribute resources, produce asymmetries of wealth and power, and push social innovation to the periphery of the system. I discuss the policy implications of these tendencies and propose avenues for follow-up research.