22,554 research outputs found
Symmetrization for Quantum Networks: a continuous-time approach
In this paper we propose a continuous-time, dissipative Markov dynamics that
asymptotically drives a network of n-dimensional quantum systems to the set of
states that are invariant under the action of the subsystem permutation group.
The Lindblad-type generator of the dynamics is built with two-body subsystem
swap operators, thus satisfying locality constraints, and preserve symmetric
observables. The potential use of the proposed generator in combination with
local control and measurement actions is illustrated with two applications: the
generation of a global pure state and the estimation of the network size.Comment: submitted to MTNS 201
Beating the Perils of Non-Convexity: Guaranteed Training of Neural Networks using Tensor Methods
Training neural networks is a challenging non-convex optimization problem,
and backpropagation or gradient descent can get stuck in spurious local optima.
We propose a novel algorithm based on tensor decomposition for guaranteed
training of two-layer neural networks. We provide risk bounds for our proposed
method, with a polynomial sample complexity in the relevant parameters, such as
input dimension and number of neurons. While learning arbitrary target
functions is NP-hard, we provide transparent conditions on the function and the
input for learnability. Our training method is based on tensor decomposition,
which provably converges to the global optimum, under a set of mild
non-degeneracy conditions. It consists of simple embarrassingly parallel linear
and multi-linear operations, and is competitive with standard stochastic
gradient descent (SGD), in terms of computational complexity. Thus, we propose
a computationally efficient method with guaranteed risk bounds for training
neural networks with one hidden layer.Comment: The tensor decomposition analysis is expanded, and the analysis of
ridge regression is added for recovering the parameters of last layer of
neural networ
The use of data-mining for the automatic formation of tactics
This paper discusses the usse of data-mining for the automatic formation of tactics. It was presented at the Workshop on Computer-Supported Mathematical Theory Development held at IJCAR in 2004. The aim of this project is to evaluate the applicability of data-mining techniques to the automatic formation of tactics from large corpuses of proofs. We data-mine information from large proof corpuses to find commonly occurring patterns. These patterns are then evolved into tactics using genetic programming techniques
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Nordic Electricity Congestion's Arrangement as a Model for Europe: Physical Constraints or Operators' Opportunity
Nordic Electricity Congestion's Arrangement as a Model for Europe: Physical Constraints or Operators' Opportunit
Proximal Methods for Hierarchical Sparse Coding
Sparse coding consists in representing signals as sparse linear combinations
of atoms selected from a dictionary. We consider an extension of this framework
where the atoms are further assumed to be embedded in a tree. This is achieved
using a recently introduced tree-structured sparse regularization norm, which
has proven useful in several applications. This norm leads to regularized
problems that are difficult to optimize, and we propose in this paper efficient
algorithms for solving them. More precisely, we show that the proximal operator
associated with this norm is computable exactly via a dual approach that can be
viewed as the composition of elementary proximal operators. Our procedure has a
complexity linear, or close to linear, in the number of atoms, and allows the
use of accelerated gradient techniques to solve the tree-structured sparse
approximation problem at the same computational cost as traditional ones using
the L1-norm. Our method is efficient and scales gracefully to millions of
variables, which we illustrate in two types of applications: first, we consider
fixed hierarchical dictionaries of wavelets to denoise natural images. Then, we
apply our optimization tools in the context of dictionary learning, where
learned dictionary elements naturally organize in a prespecified arborescent
structure, leading to a better performance in reconstruction of natural image
patches. When applied to text documents, our method learns hierarchies of
topics, thus providing a competitive alternative to probabilistic topic models
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