1,018,451 research outputs found
Feature Selection with Evolving, Fast and Slow Using Two Parallel Genetic Algorithms
Feature selection is one of the most challenging issues in machine learning,
especially while working with high dimensional data. In this paper, we address
the problem of feature selection and propose a new approach called Evolving
Fast and Slow. This new approach is based on using two parallel genetic
algorithms having high and low mutation rates, respectively. Evolving Fast and
Slow requires a new parallel architecture combining an automatic system that
evolves fast and an effortful system that evolves slow. With this architecture,
exploration and exploitation can be done simultaneously and in unison. Evolving
fast, with high mutation rate, can be useful to explore new unknown places in
the search space with long jumps; and Evolving Slow, with low mutation rate,
can be useful to exploit previously known places in the search space with short
movements. Our experiments show that Evolving Fast and Slow achieves very good
results in terms of both accuracy and feature elimination
Thinking Fast and Slow with Deep Learning and Tree Search
Sequential decision making problems, such as structured prediction, robotic
control, and game playing, require a combination of planning policies and
generalisation of those plans. In this paper, we present Expert Iteration
(ExIt), a novel reinforcement learning algorithm which decomposes the problem
into separate planning and generalisation tasks. Planning new policies is
performed by tree search, while a deep neural network generalises those plans.
Subsequently, tree search is improved by using the neural network policy to
guide search, increasing the strength of new plans. In contrast, standard deep
Reinforcement Learning algorithms rely on a neural network not only to
generalise plans, but to discover them too. We show that ExIt outperforms
REINFORCE for training a neural network to play the board game Hex, and our
final tree search agent, trained tabula rasa, defeats MoHex 1.0, the most
recent Olympiad Champion player to be publicly released.Comment: v1 to v2: - Add a value function in MCTS - Some MCTS hyper-parameters
changed - Repetition of experiments: improved accuracy and errors shown.
(note the reduction in effect size for the tpt/cat experiment) - Results from
a longer training run, including changes in expert strength in training -
Comparison to MoHex. v3: clarify independence of ExIt and AG0. v4: see
appendix
In search of an observational quantum signature of the primordial perturbations in slow-roll and ultra slow-roll inflation
In the standard inflationary paradigm, cosmological density perturbations are
generated as quantum fluctuations in the early Universe, but then undergo a
quantum-to-classical transition. A key role in this transition is played by
squeezing of the quantum state, which is a result of the strong suppression of
the decaying mode component of the perturbations. Motivated by ever improving
measurements of the cosmological perturbations, we ask whether there are
scenarios where this decaying mode is nevertheless still observable in the late
Universe, ideally leading to a ``smoking gun'' signature of the quantum nature
of the perturbations. We address this question by evolving the quantum state of
the perturbations from inflation into the post-inflationary Universe. After
recovering the standard result that in slow-roll (SR) inflation the decaying
mode is indeed hopelessly suppressed by the time the perturbations are observed
(by orders of magnitude), we turn to ultra slow-roll (USR)
inflation, a scenario in which the usual decaying mode actually grows on
super-horizon scales. Despite this drastic difference in the behavior of the
mode functions, we find also in USR that the late-Universe decaying mode
amplitude is dramatically suppressed, in fact by the same orders of
magnitude. We finally explain that this large suppression is a general result
that holds beyond the SR and USR scenarios considered and follows from a
modified version of Heisenberg's uncertainty principle and the observed
amplitude of the primordial power spectrum. The classical behavior of the
perturbations is thus closely related to the classical behavior of macroscopic
objects drawing an analogy with the position of a massive particle, the
curvature perturbations today have an enormous effective mass of order , making them highly classical.Comment: 27 pages, 7 figures. Comments welcom
A two-dimensional search for a Gauss-Newton algorithm
Original article can be found at: http://www.ici.ro/camo/journal/jamo.htmThis paper describes a fall-back procedure for use with the Gauss-Newton method for nonlinear least-squares problems. While the basic Gauss-Newton algorithm is often successful, it is well-known that it can sometimes generate poor search directions and exhibit slow convergence. For dealing with such situations we suggest a new two-dimensional search strategy. Numerical experiments indicate that the proposed technique can be effective.Peer reviewe
Search for Exotic Physics with the ANTARES Detector
Besides the detection of high energy neutrinos, the ANTARES telescope offers
an opportunity to improve sensitivity to exotic cosmological relics. In this
article we discuss the sensitivity of the ANTARES detector to elativistic
monopoles and slow nuclearites. Dedicated trigger algorithms and search
strategies are being developed to search or them. The data filtering,
background rejection selection criteria are described, as well as the expected
sensitivity of ANTARES to exotic physics.Comment: Proceedings of the 31st ICRC conference, Lodz 2009, 4 pages, 6
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