23,590 research outputs found
A Fused Elastic Net Logistic Regression Model for Multi-Task Binary Classification
Multi-task learning has shown to significantly enhance the performance of
multiple related learning tasks in a variety of situations. We present the
fused logistic regression, a sparse multi-task learning approach for binary
classification. Specifically, we introduce sparsity inducing penalties over
parameter differences of related logistic regression models to encode
similarity across related tasks. The resulting joint learning task is cast into
a form that lends itself to be efficiently optimized with a recursive variant
of the alternating direction method of multipliers. We show results on
synthetic data and describe the regime of settings where our multi-task
approach achieves significant improvements over the single task learning
approach and discuss the implications on applying the fused logistic regression
in different real world settings.Comment: 17 page
Classifiers for centrality determination in proton-nucleus and nucleus-nucleus collisions
Centrality, as a geometrical property of the collision, is crucial for the
physical interpretation of nucleus-nucleus and proton-nucleus experimental
data. However, it cannot be directly accessed in event-by-event data analysis.
Common methods for centrality estimation in A-A and p-A collisions usually rely
on a single detector (either on the signal in zero-degree calorimeters or on
the multiplicity in some semi-central rapidity range). In the present work, we
made an attempt to develop an approach for centrality determination that is
based on machine-learning techniques and utilizes information from several
detector subsystems simultaneously. Different event classifiers are suggested
and evaluated for their selectivity power in terms of the number of
nucleons-participants and the impact parameter of the collision. Finer
centrality resolution may allow to reduce impact from so-called volume
fluctuations on physical observables being studied in heavy-ion experiments
like ALICE at the LHC and fixed target experiment NA61/SHINE on SPS.Comment: To be published in proceedings of the "XIIth Quark Confinement and
the Hadron Spectrum" conference (Thessaloniki, 2016
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