13,489 research outputs found
Novelty and Reinforcement Learning in the Value System of Developmental Robots
The value system of a developmental robot signals the occurrence of salient sensory inputs, modulates the mapping from sensory inputs to action outputs, and evaluates candidate actions. In the work reported here, a low level value system is modeled and implemented. It simulates the non-associative animal learning mechanism known as habituation effect. Reinforcement learning is also integrated with novelty. Experimental results show that the proposed value system works as designed in a study of robot viewing angle selection
Joint scaling limit of site percolation on random triangulations in the metric and peanosphere sense
Recent works have shown that random triangulations decorated by critical
() Bernoulli site percolation converge in the scaling limit to a
-Liouville quantum gravity (LQG) surface (equivalently, a Brownian
surface) decorated by SLE in two different ways:
1. The triangulation, viewed as a curve-decorated metric measure space
equipped with its graph distance, the counting measure on vertices, and a
single percolation interface converges with respect to a version of the
Gromov-Hausdorff topology.
2. There is a bijective encoding of the site-percolated triangulation by
means of a two-dimensional random walk, and this walk converges to the
correlated two-dimensional Brownian motion which encodes SLE-decorated
-LQG via the mating-of-trees theorem of Duplantier-Miller-Sheffield
(2014); this is sometimes called .
We prove that one in fact has convergence in both of these
two senses simultaneously. We also improve the metric convergence result by
showing that the map decorated by the full collection of percolation interfaces
(rather than just a single interface) converges to -LQG decorated
by CLE in the metric space sense.
This is the first work to prove simultaneous convergence of any random planar
map model in the metric and peanosphere senses. Moreover, this work is an
important step in an ongoing program to prove that random triangulations
embedded into via the so-called converge
to -LQG.Comment: 55 pages; 13 Figures. Minor revision according to a referee report.
Accepted for publication at EJ
Transform Ranking: a New Method of Fitness Scaling in Genetic Algorithms
The first systematic evaluation of the effects of six existing forms of fitness scaling in genetic algorithms is presented alongside a new method called transform ranking. Each method has been applied to stochastic universal sampling (SUS) over a fixed number of generations. The test functions chosen were the two-dimensional Schwefel and Griewank functions. The quality of the solution was improved by applying sigma scaling, linear rank scaling, nonlinear rank scaling, probabilistic nonlinear rank scaling, and transform ranking. However, this benefit was always at a computational cost. Generic linear scaling and Boltzmann scaling were each of benefit in one fitness landscape but not the other. A new fitness scaling function, transform ranking, progresses from linear to nonlinear rank scaling during the evolution process according to a transform schedule. This new form of fitness scaling was found to be one of the two methods offering the greatest improvements in the quality of search. It provided the best improvement in the quality of search for the Griewank function, and was second only to probabilistic nonlinear rank scaling for the Schwefel function. Tournament selection, by comparison, was always the computationally cheapest option but did not necessarily find the best solutions
Bayesian Optimization for Adaptive MCMC
This paper proposes a new randomized strategy for adaptive MCMC using
Bayesian optimization. This approach applies to non-differentiable objective
functions and trades off exploration and exploitation to reduce the number of
potentially costly objective function evaluations. We demonstrate the strategy
in the complex setting of sampling from constrained, discrete and densely
connected probabilistic graphical models where, for each variation of the
problem, one needs to adjust the parameters of the proposal mechanism
automatically to ensure efficient mixing of the Markov chains.Comment: This paper contains 12 pages and 6 figures. A similar version of this
paper has been submitted to AISTATS 2012 and is currently under revie
Towards a unified lattice kinetic scheme for relativistic hydrodynamics
We present a systematic derivation of relativistic lattice kinetic equations
for finite-mass particles, reaching close to the zero-mass ultra-relativistic
regime treated in the previous literature. Starting from an expansion of the
Maxwell-Juettner distribution on orthogonal polynomials, we perform a
Gauss-type quadrature procedure and discretize the relativistic Boltzmann
equation on space-filling Cartesian lattices. The model is validated through
numerical comparison with standard benchmark tests and solvers in relativistic
fluid dynamics such as Boltzmann approach multiparton scattering (BAMPS) and
previous relativistic lattice Boltzmann models. This work provides a
significant step towards the formulation of a unified relativistic lattice
kinetic scheme, covering both massive and near-massless particles regimes
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