1,530 research outputs found
Deep Bilevel Learning
We present a novel regularization approach to train neural networks that
enjoys better generalization and test error than standard stochastic gradient
descent. Our approach is based on the principles of cross-validation, where a
validation set is used to limit the model overfitting. We formulate such
principles as a bilevel optimization problem. This formulation allows us to
define the optimization of a cost on the validation set subject to another
optimization on the training set. The overfitting is controlled by introducing
weights on each mini-batch in the training set and by choosing their values so
that they minimize the error on the validation set. In practice, these weights
define mini-batch learning rates in a gradient descent update equation that
favor gradients with better generalization capabilities. Because of its
simplicity, this approach can be integrated with other regularization methods
and training schemes. We evaluate extensively our proposed algorithm on several
neural network architectures and datasets, and find that it consistently
improves the generalization of the model, especially when labels are noisy.Comment: ECCV 201
Group Theory and Quasiprobability Integrals of Wigner Functions
The integral of the Wigner function of a quantum mechanical system over a
region or its boundary in the classical phase plane, is called a
quasiprobability integral. Unlike a true probability integral, its value may
lie outside the interval [0,1]. It is characterized by a corresponding
selfadjoint operator, to be called a region or contour operator as appropriate,
which is determined by the characteristic function of that region or contour.
The spectral problem is studied for commuting families of region and contour
operators associated with concentric disks and circles of given radius a. Their
respective eigenvalues are determined as functions of a, in terms of the
Gauss-Laguerre polynomials. These polynomials provide a basis of vectors in
Hilbert space carrying the positive discrete series representations of the
algebra su(1,1)or so(2,1). The explicit relation between the spectra of
operators associated with disks and circles with proportional radii, is given
in terms of the dicrete variable Meixner polynomials.Comment: 11 pages, latex fil
A new approach to quantum backflow
We derive some rigorous results concerning the backflow operator introduced
by Bracken and Melloy. We show that it is linear bounded, self adjoint, and not
compact. Thus the question is underlined whether the backflow constant is an
eigenvalue of the backflow operator. From the position representation of the
backflow operator we obtain a more efficient method to determine the backflow
constant. Finally, detailed position probability flow properties of a numerical
approximation to the (perhaps improper) wave function of maximal backflow are
displayed.Comment: 12 pages, 8 figure
Solutions to the Quantum Yang-Baxter Equation with Extra Non-Additive Parameters
We present a systematic technique to construct solutions to the Yang-Baxter
equation which depend not only on a spectral parameter but in addition on
further continuous parameters. These extra parameters enter the Yang-Baxter
equation in a similar way to the spectral parameter but in a non-additive form.
We exploit the fact that quantum non-compact algebras such as
and type-I quantum superalgebras such as and are
known to admit non-trivial one-parameter families of infinite-dimensional and
finite dimensional irreps, respectively, even for generic . We develop a
technique for constructing the corresponding spectral-dependent R-matrices. As
examples we work out the the -matrices for the three quantum algebras
mentioned above in certain representations.Comment: 13 page
Trauma as counter-revolutionary colonisation: narratives from (post)revolutionary Egypt
We argue that multiple levels of trauma were present in Egypt before, during and after the 2011 revolution. Individual, social and political trauma constitute a triangle of traumatisation which was strategically employed by the Egyptian counter-revolutionary forces â primarily the army and the leadership of the Muslim Brotherhood â to maintain their political and economic power over and above the social, economic and political interests of others. Through the destruction of physical bodies, the fragmentation and polarisation of social relations and the violent closure of the newly emerged political public sphere, these actors actively repressed the potential for creative and revolutionary transformation. To better understand this multi-layered notion of trauma, we turn to Habermasâ âcolonisation of the lifeworldâ thesis which offers a critical lens through which to examine the wider political and economic structures and context in which trauma occurred as well as its effects on the personal, social and political realms. In doing so, we develop a novel conception of trauma that acknowledges individual, social and political dimensions. We apply this conceptual framing to empirical narratives of trauma in Egyptâs pre- and post-revolutionary phases, thus both developing a non-Western application of Habermasâ framework and revealing ethnographic accounts of the revolution by activists in Cairo
Comments on Drinfeld Realization of Quantum Affine Superalgebra and its Hopf Algebra Structure
By generalizing the Reshetikhin and Semenov-Tian-Shansky construction to
supersymmetric cases, we obtain Drinfeld current realization for quantum affine
superalgebra . We find a simple coproduct for the quantum
current generators and establish the Hopf algebra structure of this super
current algebra.Comment: Some errors and misprints corrected and a remark in section 4
removed. 12 pages, Latex fil
Lattice Models
In this paper I construct lattice models with an underlying
superalgebra symmetry. I find new solutions to the graded Yang-Baxter equation.
These {\it trigonometric} -matrices depend on {\it three} continuous
parameters, the spectral parameter, the deformation parameter and the
parameter, , of the superalgebra. It must be emphasized that the
parameter is generic and the parameter does not correspond to the
`nilpotency' parameter of \cite{gs}. The rational limits are given; they also
depend on the parameter and this dependence cannot be rescaled away. I
give the Bethe ansatz solution of the lattice models built from some of these
-matrices, while for other matrices, due to the particular nature of the
representation theory of , I conjecture the result. The parameter
appears as a continuous generalized spin. Finally I briefly discuss the problem
of finding the ground state of these models.Comment: 19 pages, plain LaTeX, no figures. Minor changes (version accepted
for publication
Tina Fuchs Interview 2016
A 2016 interview with Tina Fuchs, the Dean of Students at Western Oregon University. In her interview, she discusses her career and the changes in student diversity and sustainability that she has witnessed over her 27 years at as an administrator at Western Oregon University
Localization and Causality for a free particle
Theorems (most notably by Hegerfeldt) prove that an initially localized
particle whose time evolution is determined by a positive Hamiltonian will
violate causality. We argue that this apparent paradox is resolved for a free
particle described by either the Dirac equation or the Klein-Gordon equation
because such a particle cannot be localized in the sense required by the
theorems.Comment: 9 pages,no figures,new section adde
- âŠ