Complete dictionary recovery over the sphere I: Overview and the geometric picture
We consider the problem of recovering a complete (ie, square and invertible) matrix A 0,
from Y∈ R n× p with Y= A 0 X 0, provided X 0 is sufficiently sparse. This recovery problem is …
from Y∈ R n× p with Y= A 0 X 0, provided X 0 is sufficiently sparse. This recovery problem is …
A geometric analysis of phase retrieval
Can we recover a complex signal from its Fourier magnitudes? More generally, given a set
of m measurements, y_k=\left| a _k^* x\right| yk= ak∗ x for k= 1, ..., mk= 1,…, m, is it possible …
of m measurements, y_k=\left| a _k^* x\right| yk= ak∗ x for k= 1, ..., mk= 1,…, m, is it possible …
Feature purification: How adversarial training performs robust deep learning
Despite the empirical success of using adversarial training to defend deep learning models
against adversarial perturbations, so far, it still remains rather unclear what the principles are …
against adversarial perturbations, so far, it still remains rather unclear what the principles are …
Global rates of convergence for nonconvex optimization on manifolds
We consider the minimization of a cost function f on a manifold using Riemannian gradient
descent and Riemannian trust regions (RTR). We focus on satisfying necessary optimality …
descent and Riemannian trust regions (RTR). We focus on satisfying necessary optimality …
Solving random quadratic systems of equations is nearly as easy as solving linear systems
This paper is concerned with finding a solution x to a quadratic system of equations yi=|< ai,
x>|^ 2, i= 1, 2,..., m. We prove that it is possible to solve unstructured quadratic systems in n …
x>|^ 2, i= 1, 2,..., m. We prove that it is possible to solve unstructured quadratic systems in n …
Nonconvex phase synchronization
N Boumal - SIAM Journal on Optimization, 2016 - SIAM
We estimate n phases (angles) from noisy pairwise relative phase measurements. The task
is modeled as a nonconvex least-squares optimization problem. It was recently shown that …
is modeled as a nonconvex least-squares optimization problem. It was recently shown that …
[LIBRO][B] Dictionary learning algorithms and applications
B Dumitrescu, P Irofti - 2018 - Springer
This book revolves around the question of designing a matrix D∈ Rm× n called dictionary,
such that to obtain good sparse representations y≈ Dx for a class of signals y∈ Rm given …
such that to obtain good sparse representations y≈ Dx for a class of signals y∈ Rm given …
Complete dictionary recovery over the sphere II: Recovery by Riemannian trust-region method
We consider the problem of recovering a complete (ie, square and invertible) matrix A 0,
from Y∈ R n× p with Y= A 0 X 0, provided X 0 is sufficiently sparse. This recovery problem is …
from Y∈ R n× p with Y= A 0 X 0, provided X 0 is sufficiently sparse. This recovery problem is …
The power of normalization: Faster evasion of saddle points
KY Levy - arxiv preprint arxiv:1611.04831, 2016 - arxiv.org
A commonly used heuristic in non-convex optimization is Normalized Gradient Descent
(NGD)-a variant of gradient descent in which only the direction of the gradient is taken into …
(NGD)-a variant of gradient descent in which only the direction of the gradient is taken into …
When are nonconvex problems not scary?
In this note, we focus on smooth nonconvex optimization problems that obey:(1) all local
minimizers are also global; and (2) around any saddle point or local maximizer, the objective …
minimizers are also global; and (2) around any saddle point or local maximizer, the objective …