3,903 research outputs found
Ensemble learning of linear perceptron; Online learning theory
Within the framework of on-line learning, we study the generalization error
of an ensemble learning machine learning from a linear teacher perceptron. The
generalization error achieved by an ensemble of linear perceptrons having
homogeneous or inhomogeneous initial weight vectors is precisely calculated at
the thermodynamic limit of a large number of input elements and shows rich
behavior. Our main findings are as follows. For learning with homogeneous
initial weight vectors, the generalization error using an infinite number of
linear student perceptrons is equal to only half that of a single linear
perceptron, and converges with that of the infinite case with O(1/K) for a
finite number of K linear perceptrons. For learning with inhomogeneous initial
weight vectors, it is advantageous to use an approach of weighted averaging
over the output of the linear perceptrons, and we show the conditions under
which the optimal weights are constant during the learning process. The optimal
weights depend on only correlation of the initial weight vectors.Comment: 14 pages, 3 figures, submitted to Physical Review
Statistical Mechanics of Nonlinear On-line Learning for Ensemble Teachers
We analyze the generalization performance of a student in a model composed of
nonlinear perceptrons: a true teacher, ensemble teachers, and the student. We
calculate the generalization error of the student analytically or numerically
using statistical mechanics in the framework of on-line learning. We treat two
well-known learning rules: Hebbian learning and perceptron learning. As a
result, it is proven that the nonlinear model shows qualitatively different
behaviors from the linear model. Moreover, it is clarified that Hebbian
learning and perceptron learning show qualitatively different behaviors from
each other. In Hebbian learning, we can analytically obtain the solutions. In
this case, the generalization error monotonically decreases. The steady value
of the generalization error is independent of the learning rate. The larger the
number of teachers is and the more variety the ensemble teachers have, the
smaller the generalization error is. In perceptron learning, we have to
numerically obtain the solutions. In this case, the dynamical behaviors of the
generalization error are non-monotonic. The smaller the learning rate is, the
larger the number of teachers is; and the more variety the ensemble teachers
have, the smaller the minimum value of the generalization error is.Comment: 13 pages, 9 figure
Dyons in N=4 Supersymmetric Theories and Three-Pronged Strings
We construct and explore BPS states that preserve 1/4 of supersymmetry in N=4
Yang-Mills theories. Such states are also realized as three-pronged strings
ending on D3-branes. We correct the electric part of the BPS equation and
relate its solutions to the unbroken abelian gauge group generators. Generic
1/4-BPS solitons are not spherically symmetric, but consist of two or more
dyonic components held apart by a delicate balance between static
electromagnetic force and scalar Higgs force. The instability previously found
in three-pronged string configurations is due to excessive repulsion by one of
these static forces. We also present an alternate construction of these 1/4-BPS
states from quantum excitations around a magnetic monopole, and build up the
supermultiplet for arbitrary (quantized) electric charge. The degeneracy and
the highest spin of the supermultiplet increase linearly with a relative
electric charge. We conclude with comments.Comment: 33 pages, two figures, LaTex, a footnote added, the figure caption of
Fig.2 expanded, one more referenc
Statistical Mechanics of Time Domain Ensemble Learning
Conventional ensemble learning combines students in the space domain. On the
other hand, in this paper we combine students in the time domain and call it
time domain ensemble learning. In this paper, we analyze the generalization
performance of time domain ensemble learning in the framework of online
learning using a statistical mechanical method. We treat a model in which both
the teacher and the student are linear perceptrons with noises. Time domain
ensemble learning is twice as effective as conventional space domain ensemble
learning.Comment: 10 pages, 10 figure
Statistical Mechanics of Linear and Nonlinear Time-Domain Ensemble Learning
Conventional ensemble learning combines students in the space domain. In this
paper, however, we combine students in the time domain and call it time-domain
ensemble learning. We analyze, compare, and discuss the generalization
performances regarding time-domain ensemble learning of both a linear model and
a nonlinear model. Analyzing in the framework of online learning using a
statistical mechanical method, we show the qualitatively different behaviors
between the two models. In a linear model, the dynamical behaviors of the
generalization error are monotonic. We analytically show that time-domain
ensemble learning is twice as effective as conventional ensemble learning.
Furthermore, the generalization error of a nonlinear model features
nonmonotonic dynamical behaviors when the learning rate is small. We
numerically show that the generalization performance can be improved remarkably
by using this phenomenon and the divergence of students in the time domain.Comment: 11 pages, 7 figure
The RNA helicase Dbp7 promotes domain V/VI compaction and stabilization of inter-domain interactions during early 60S assembly
Early pre-60S ribosomal particles are poorly characterized, highly dynamic complexes that undergo extensive rRNA folding and compaction concomitant with assembly of ribosomal proteins and exchange of assembly factors. Pre-60S particles contain numerous RNA helicases, which are likely regulators of accurate and efficient formation of appropriate rRNA structures. Here we reveal binding of the RNA helicase Dbp7 to domain V/VI of early pre- 60S particles in yeast and show that in the absence of this protein, dissociation of the Npa1 scaffolding complex, release of the snR190 folding chaperone, recruitment of the A3 cluster factors and binding of the ribosomal protein uL3 are impaired. uL3 is critical for formation of the peptidyltransferase center (PTC) and is responsible for stabilizing interac- tions between the 5′ and 3′ ends of the 25S, an essential pre-requisite for subsequent pre- 60S maturation events. Highlighting the importance of pre-ribosome remodeling by Dbp7, our data suggest that in the absence of Dbp7 or its catalytic activity, early pre-ribosomal particles are targeted for degradation
Zero-Mode Dynamics of String Webs
At sufficiently low energy the dynamics of a string web is dominated by zero
modes involving rigid motion of the internal strings. The dimension of the
associated moduli space equals the maximal number of internal faces in the web.
The generic web moduli space has boundaries and multiple branches, and for webs
with three or more faces the geometry is curved. Webs can also be studied in a
lift to M-theory, where a string web is replaced by a membrane wrapped on a
holomorphic curve in spacetime. In this case the moduli space is complexified
and admits a Kaehler metric.Comment: LaTeX, 17 pages, 5 eps figures; v2: references adde
Moduli Space Dimensions of Multi-Pronged Strings
The numbers of bosonic and fermionic zero modes of multi-pronged strings are
counted in super-Yang-Mills theory and compared with those of the
IIB string theory. We obtain a nice agreement for the fermionic zero modes,
while our result for the bosonic zero modes differs from that obtained in the
IIB string theory. The possible origin of the discrepancy is discussedComment: 15 pages, 2 figure
Momentum modes of M5-branes in a 2d space
We study M5 branes by considering the selfdual strings parallel to a plane.
With the internal oscillation frozen, each selfdual string gives a 5d SYM
field. All selfdual strings together give a 6d field with 5 scalars, 3 gauge
degrees of freedom and 8 fermionic degrees of freedom in adjoint representation
of U(N). Selfdual strings with the same orientation have the SYM-type
interaction. For selfdual strings with the different orientations, which could
also be taken as the unparallel momentum modes of the 6d field on that plane or
the (p,q) (r,s) strings on D3 with (p,q)\neq (r,s), the [i,j]+[j,k]\rightarrow
[i,k] relation is not valid, so the coupling cannot be written in terms of the
standard N \times N matrix multiplication. 3-string junction, which is the
bound state of the unparallel [i,j] [j,k] selfdual strings, may play a role
here.Comment: 37 pages, 5 figures, to appear in JHEP; v2: reference adde
Social Interactions vs Revisions, What is important for Promotion in Wikipedia?
In epistemic community, people are said to be selected on their knowledge
contribution to the project (articles, codes, etc.) However, the socialization
process is an important factor for inclusion, sustainability as a contributor,
and promotion. Finally, what does matter to be promoted? being a good
contributor? being a good animator? knowing the boss? We explore this question
looking at the process of election for administrator in the English Wikipedia
community. We modeled the candidates according to their revisions and/or social
attributes. These attributes are used to construct a predictive model of
promotion success, based on the candidates's past behavior, computed thanks to
a random forest algorithm.
Our model combining knowledge contribution variables and social networking
variables successfully explain 78% of the results which is better than the
former models. It also helps to refine the criterion for election. If the
number of knowledge contributions is the most important element, social
interactions come close second to explain the election. But being connected
with the future peers (the admins) can make the difference between success and
failure, making this epistemic community a very social community too
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