1,852 research outputs found
Self-Paced Learning: an Implicit Regularization Perspective
Self-paced learning (SPL) mimics the cognitive mechanism of humans and
animals that gradually learns from easy to hard samples. One key issue in SPL
is to obtain better weighting strategy that is determined by minimizer
function. Existing methods usually pursue this by artificially designing the
explicit form of SPL regularizer. In this paper, we focus on the minimizer
function, and study a group of new regularizer, named self-paced implicit
regularizer that is deduced from robust loss function. Based on the convex
conjugacy theory, the minimizer function for self-paced implicit regularizer
can be directly learned from the latent loss function, while the analytic form
of the regularizer can be even known. A general framework (named SPL-IR) for
SPL is developed accordingly. We demonstrate that the learning procedure of
SPL-IR is associated with latent robust loss functions, thus can provide some
theoretical inspirations for its working mechanism. We further analyze the
relation between SPL-IR and half-quadratic optimization. Finally, we implement
SPL-IR to both supervised and unsupervised tasks, and experimental results
corroborate our ideas and demonstrate the correctness and effectiveness of
implicit regularizers.Comment: 12 pages, 3 figure
-choosability of planar graphs with -cycles far apart via the Combinatorial Nullstellensatz
By a well-known theorem of Thomassen and a planar graph depicted by Voigt, we
know that every planar graph is -choosable, and the bound is tight. In 1999,
Lam, Xu and Liu reduced to on -free planar graphs. In the paper,
by applying the famous Combinatorial Nullstellensatz, we design an effective
algorithm to deal with list coloring problems. At the same time, we prove that
a planar graph is -choosable if any two -cycles having distance at
least in , which extends the result of Lam et al
Ultrathin Acoustic Parity-Time Symmetric Metasurface Cloak
Invisibility or unhearability cloaks have beenmade possible by using metamaterials enabling light or sound to flow around obstacle
without the trace of reflections or shadows. Metamaterials are known for being flexible building units that can mimic a host of
unusual and extreme material responses, which are essential when engineering artificial material properties to realize a coordinate
transforming cloak. Bending and stretching the coordinate grid in space require stringent material parameters; therefore, small
inaccuracies and inevitablematerial losses become sources for unwanted scattering that are decremental to the desired effect.These
obstacles further limit the possibility of achieving a robust concealment of sizeable objects from either radar or sonar detection. By
using an elaborate arrangement of gain and lossy acousticmedia respecting parity-time symmetry, we built a one-way unhearability
cloak able to hide objects seven times larger than the acoustic wavelength. Generally speaking, our approach has no limits in terms
of working frequency, shape, or size, specifically though we demonstrate how, in principle, an object of the size of a human can be
hidden from audible sound
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