Publications related to Continuity Properties of Law-Invariant (Quasi-)Convex Risk Functions on L∞

Stability of Image-Reconstruction Algorithms

Michaël Unser, Sebastian Jonas Neumayer, Pol del Aguila Pla

Robustness and stability of image-reconstruction algorithms have recently come under scrutiny. Their importance to medical imaging cannot be overstated. We review the known results for the topical variational regularization strategies ( ℓ2 and ℓ1 regulariz ...

2023

Gradient-based optimisation of the conditional-value-at-risk using the multi-level Monte Carlo method

Fabio Nobile, Sundar Subramaniam Ganesh

In this work, we tackle the problem of minimising the Conditional-Value-at-Risk (CVaR) of output quantities of complex differential models with random input data, using gradient-based approaches in combination with the Multi-Level Monte Carlo (MLMC) method ...

2022

A first-order primal-dual method with adaptivity to local smoothness

Volkan Cevher, Maria-Luiza Vladarean

We consider the problem of finding a saddle point for the convex-concave objective

\min_x \max_y f(x) + \langle Ax, y\rangle - g^*(y)

, where

f

is a convex function with locally Lipschitz gradient and

g

is convex and possibly non-smooth. We propose an ...

2021

Convex optimization in sums of Banach spaces

Michaël Unser, Shayan Aziznejad

We characterize the solution of a broad class of convex optimization problems that address the reconstruction of a function from a finite number of linear measurements. The underlying hypothesis is that the solution is decomposable as a finite sum of compo ...

2021

Adaptive Gradient Descent without Descent

Konstantin Mishchenko

We present a strikingly simple proof that two rules are sufficient to automate gradient descent: 1) don’t increase the stepsize too fast and 2) don’t overstep the local curvature. No need for functional values, no line search, no information about the func ...

2020

A Multi-Agent Primal-Dual Strategy for Composite Optimization over Distributed Features

Ali H. Sayed, Sulaiman A S A E Alghunaim, Ming Yan

This work studies multi-agent sharing optimization problems with the objective function being the sum of smooth local functions plus a convex (possibly non-smooth) function coupling all agents. This scenario arises in many machine learning and engineering ...

IEEE2020

On the Almost Sure Convergence of Stochastic Gradient Descent in Non-Convex Problems

Volkan Cevher, Ali Kavis, Shaul Nadav Hallak

This paper analyzes the trajectories of stochastic gradient descent (SGD) to help understand the algorithm’s convergence properties in non-convex problems. We first show that the sequence of iterates generated by SGD remains bounded and converges with prob ...

2020

Stochastic Frank-Wolfe for Composite Convex Minimization

Volkan Cevher, Alp Yurtsever

A broad class of convex optimization problems can be formulated as a semidefinite program (SDP), minimization of a convex function over the positive-semidefinite cone subject to some affine constraints. The majority of classical SDP solvers are designed fo ...

2019

Discrete-time regional pole-placement using convex approximations: Theory and application to a boost converter

Emilio Maddalena

The problem of allocating the closed-loop poles of linear systems in specific regions of the complex plane defined by discrete time-domain requirements is addressed. The resulting non-convex set is inner-approximated by a convex region described with linea ...

2019

Optimistic Distributionally Robust Optimization for Nonparametric Likelihood Approximation

Daniel Kuhn, Viet Anh Nguyen, Soroosh Shafieezadeh Abadeh, Wolfram Wiesemann

The likelihood function is a fundamental component in Bayesian statistics. However, evaluating the likelihood of an observation is computationally intractable in many applications. In this paper, we propose a non-parametric approximation of the likelihood ...

2019

Continuity Properties of Law-Invariant (Quasi-)Convex Risk Functions on L∞

Graph Chatbot

Chat with Graph Search

Stability of Image-Reconstruction Algorithms

Gradient-based optimisation of the conditional-value-at-risk using the multi-level Monte Carlo method

A first-order primal-dual method with adaptivity to local smoothness

Convex optimization in sums of Banach spaces

Adaptive Gradient Descent without Descent

A Multi-Agent Primal-Dual Strategy for Composite Optimization over Distributed Features

On the Almost Sure Convergence of Stochastic Gradient Descent in Non-Convex Problems

Stochastic Frank-Wolfe for Composite Convex Minimization

Discrete-time regional pole-placement using convex approximations: Theory and application to a boost converter

Optimistic Distributionally Robust Optimization for Nonparametric Likelihood Approximation

Gradient-based optimisation of the conditional-value-at-risk using the multi-level Monte Carlo method

Stability of Image-Reconstruction Algorithms

Optimistic Distributionally Robust Optimization for Nonparametric Likelihood Approximation

Convex optimization in sums of Banach spaces

Adaptive Gradient Descent without Descent

On the Almost Sure Convergence of Stochastic Gradient Descent in Non-Convex Problems

A first-order primal-dual method with adaptivity to local smoothness

A Multi-Agent Primal-Dual Strategy for Composite Optimization over Distributed Features

Discrete-time regional pole-placement using convex approximations: Theory and application to a boost converter

Stochastic Frank-Wolfe for Composite Convex Minimization