8 research outputs found
A/B Testing and Best-arm Identification for Linear Bandits with Robustness to Non-stationarity
We investigate the fixed-budget best-arm identification (BAI) problem for
linear bandits in a potentially non-stationary environment. Given a finite arm
set , a fixed budget , and an unpredictable
sequence of parameters , an
algorithm will aim to correctly identify the best arm with probability as
high as possible. Prior work has addressed the stationary setting where
for all and demonstrated that the error probability
decreases as for a problem-dependent constant . But
in many real-world multivariate testing scenarios that motivate our
work, the environment is non-stationary and an algorithm expecting a stationary
setting can easily fail. For robust identification, it is well-known that if
arms are chosen randomly and non-adaptively from a G-optimal design over
at each time then the error probability decreases as
, where . As there exist environments where
, we are motivated to propose a novel
algorithm - that aims to obtain the best of both
worlds: robustness to non-stationarity and fast rates of identification in
benign settings. We characterize the error probability of
- and demonstrate empirically that the algorithm
indeed never performs worse than G-optimal design but compares favorably to the
best algorithms in the stationary setting.Comment: 25 pages, 6 figure
Spatial assessment of fishing effort around European marine reserves: Implications for successful fisheries management
9 pages, 3 figures, 4 tablesWe examined the spatial dynamic of artisanal fishing fleets around five European marine protected areas (MPAs) to derive general implications for the evaluation of MPAs as fisheries management tools. The coastal MPAs studied were located off France, Malta and Spain and presented a variety of spatial designs and processes of establishment. We developed a standardized methodology to define factors influencing effort allocation and to produce fishing effort maps by merging GIS with geostatistical modelling techniques. Results revealed that in most cases the factors âdistance to the no-takeâ, âwater depthâ, and âdistance to the portâ had a significant influence on effort allocation by the fishing fleets. Overall, we found local concentration of fishing effort around the MPA borders. Thus, neglecting the pattern of fishing effort distribution in evaluating MPA benefits, such as spillover of biomass, could hamper sound interpretation of MPAs as fisheries management toolsThis manuscript is a product of the fisheries working package (WP2) of the European Commission project âMarine Protected Areas as Tools for Fisheries Management and Conservationâ (EMPAFISH; Contract No. 006539). Part of the data collected for this study was also funded by the European project BIOMEX (Contract No. QLRT-2001-00891). The first author was sponsored by a research fellowship of the German Research Foundation (DFG)Peer reviewe
Approche en chimie environnementale : de la quantification ciblée de contaminnats à l'évaluation de la contamination du milieu aquatique par une approche non ciblée.
communication par afficheNational audienc
Cytonuclear interactions affect adaptive traits of the annual plant Arabidopsis thaliana in the field
International audienc
L'Aide Ă la DĂ©cision Ă l'IRIT
Bulletin AFI