9,320 research outputs found
A Meta-Theory of Boundary Detection Benchmarks
Human labeled datasets, along with their corresponding evaluation algorithms,
play an important role in boundary detection. We here present a psychophysical
experiment that addresses the reliability of such benchmarks. To find better
remedies to evaluate the performance of any boundary detection algorithm, we
propose a computational framework to remove inappropriate human labels and
estimate the intrinsic properties of boundaries.Comment: NIPS 2012 Workshop on Human Computation for Science and Computational
Sustainabilit
Linear and Order Statistics Combiners for Pattern Classification
Several researchers have experimentally shown that substantial improvements
can be obtained in difficult pattern recognition problems by combining or
integrating the outputs of multiple classifiers. This chapter provides an
analytical framework to quantify the improvements in classification results due
to combining. The results apply to both linear combiners and order statistics
combiners. We first show that to a first order approximation, the error rate
obtained over and above the Bayes error rate, is directly proportional to the
variance of the actual decision boundaries around the Bayes optimum boundary.
Combining classifiers in output space reduces this variance, and hence reduces
the "added" error. If N unbiased classifiers are combined by simple averaging,
the added error rate can be reduced by a factor of N if the individual errors
in approximating the decision boundaries are uncorrelated. Expressions are then
derived for linear combiners which are biased or correlated, and the effect of
output correlations on ensemble performance is quantified. For order statistics
based non-linear combiners, we derive expressions that indicate how much the
median, the maximum and in general the ith order statistic can improve
classifier performance. The analysis presented here facilitates the
understanding of the relationships among error rates, classifier boundary
distributions, and combining in output space. Experimental results on several
public domain data sets are provided to illustrate the benefits of combining
and to support the analytical results.Comment: 31 page
A hybrid algorithm for Bayesian network structure learning with application to multi-label learning
We present a novel hybrid algorithm for Bayesian network structure learning,
called H2PC. It first reconstructs the skeleton of a Bayesian network and then
performs a Bayesian-scoring greedy hill-climbing search to orient the edges.
The algorithm is based on divide-and-conquer constraint-based subroutines to
learn the local structure around a target variable. We conduct two series of
experimental comparisons of H2PC against Max-Min Hill-Climbing (MMHC), which is
currently the most powerful state-of-the-art algorithm for Bayesian network
structure learning. First, we use eight well-known Bayesian network benchmarks
with various data sizes to assess the quality of the learned structure returned
by the algorithms. Our extensive experiments show that H2PC outperforms MMHC in
terms of goodness of fit to new data and quality of the network structure with
respect to the true dependence structure of the data. Second, we investigate
H2PC's ability to solve the multi-label learning problem. We provide
theoretical results to characterize and identify graphically the so-called
minimal label powersets that appear as irreducible factors in the joint
distribution under the faithfulness condition. The multi-label learning problem
is then decomposed into a series of multi-class classification problems, where
each multi-class variable encodes a label powerset. H2PC is shown to compare
favorably to MMHC in terms of global classification accuracy over ten
multi-label data sets covering different application domains. Overall, our
experiments support the conclusions that local structural learning with H2PC in
the form of local neighborhood induction is a theoretically well-motivated and
empirically effective learning framework that is well suited to multi-label
learning. The source code (in R) of H2PC as well as all data sets used for the
empirical tests are publicly available.Comment: arXiv admin note: text overlap with arXiv:1101.5184 by other author
A to Z of the Muon anomalous magnetic moment in the MSSM with Pati-Salam at the GUT scale
We analyse the low energy predictions of the minimal supersymmetric standard model (MSSM) arising from a GUT scale Pati-Salam gauge group further constrained by an A4 × Z5 family symmetry, resulting in four soft scalar masses at the GUT scale: one left-handed soft mass m0 and three right-handed soft masses m1, m2, m3, one for each generation. We demonstrate that this model, which was initially developed to describe the neutrino sector, can explain collider and non-collider measurements such as the dark matter relic density, the Higgs boson mass and, in particular, the anomalous magnetic moment of the muon (g − 2)μ. Since about two decades, (g − 2)μ suffers a puzzling about 3σ excessoftheexperimentallymeasuredvalueoverthetheoreticalprediction,whichour model is able to fully resolve. As the consequence of this resolution, our model predicts specific regions of the parameter space with the specific properties including light smuons and neutralinos, which could also potentially explain di-lepton excesses observed by CMS and ATLAS
The No-Scale Multiverse at the LHC
We present a contemporary perspective on the String Landscape and the
Multiverse of plausible string, M- and F-theory vacua, seeking to demonstrate a
non-zero probability for the existence of a universe matching our own observed
physics within the solution ensemble, arguing for the importance of No-Scale
Supergravity as an essential common underpinning. Our context is a highly
detailed phenomenological probe of No-Scale F-SU(5), a model representing the
intersection of the F-lipped SU(5) X U(1)_X Grand Unified Theory (GUT) with
extra TeV-Scale vector-like multiplets derived out of F-theory, and the
dynamics of No-Scale Supergravity. We present a highly constrained "Golden"
region with tan(beta) \sim 15, m_t = 173.0 - 174.4 GeV, M_1/2 = 455 - 481 GeV,
and M_V = 691 - 1020 GeV, which simultaneously satisfies all known experimental
constraints. We supplement this bottom-up phenomenological perspective with a
top-down theoretical analysis of the one-loop effective Higgs potential,
achieving a striking consonance via the dynamic determination of tan(beta) and
M_1/2 at the local secondary minimization of the spontaneously broken
electroweak Higgs vacuum V_min. We present the distinctive signatures of
No-Scale F-SU(5) at the LHC, where a light stop and gluino are expected to
generate a surplus of ultra-high multiplicity (>= 9) hadronic jet events. We
propose modest alterations to the canonical background selection cut strategy
which would enhance resolution of these events, while readily suppressing the
contribution of all Standard Model processes, and allowing a clear
differentiation from competing models of new physics. Detection by the LHC of
the ultra-high jet signal would constitute a suggestive evocation of the
intimately linked stringy origins of F-SU(5), and could provide a glimpse into
the fundamental string moduli, and possibly even the workings of the No-Scale
Multiverse.Comment: A review of recent work, submitted to the DICE 2010 Workshop
proceedings, based on the invited talk by D.V.N. (20 Pages, 5 Tables, 18
Figures
Cosmological Phase Transitions and their Properties in the NMSSM
We study cosmological phase transitions in the Next-to-Minimal Supersymmetric
Standard Model (NMSSM) in light of the Higgs discovery. We use an effective
field theory approach to calculate the finite temperature effective potential,
focusing on regions with significant tree-level contributions to the Higgs
mass, a viable neutralino dark matter candidate, 1-2 TeV stops, and with the
remaining particle spectrum compatible with current LHC searches and results.
The phase transition structure in viable regions of parameter space exhibits a
rich phenomenology, potentially giving rise to one- or two-step first-order
phase transitions in the singlet and/or directions. We compute several
parameters pertaining to the bubble wall profile, including the bubble wall
width and (the variation of the ratio in Higgs vacuum expectation
values across the wall). These quantities can vary significantly across small
regions of parameter space and can be promising for successful electroweak
baryogenesis. We estimate the wall velocity microphysically, taking into
account the various sources of friction acting on the expanding bubble wall.
Ultra-relativistic solutions to the bubble wall equations of motion typically
exist when the electroweak phase transition features substantial supercooling.
For somewhat weaker transitions, the bubble wall instead tends to be
sub-luminal and, in fact, likely sub-sonic, suggesting that successful
electroweak baryogenesis may indeed occur in regions of the NMSSM compatible
with the Higgs discovery.Comment: 49 pages + 2 appendices, 6 figures. v2: Minor corrections; matches
version published in JHE
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