Publications associées à Point d'inflexion

Development of a new method to determine the axial void velocity profile in BWRs from measurements of the in-core neutron noise

Determination of the local void fraction in BWRs from in-core neutron noise measurements requires the knowledge of the axial velocity of the void. The purpose of this paper is to revisit the problem of determining the axial void velocity profile from the t ...

PERGAMON-ELSEVIER SCIENCE LTD2021

Geometry of the Loss Landscape in Overparameterized Neural Networks: Symmetries and Invariances

Wulfram Gerstner, Clément Hongler, Johanni Michael Brea, Francesco Spadaro, Berfin Simsek, Arthur Jacot

We study how permutation symmetries in overparameterized multi-layer neural networks generate `symmetry-induced' critical points. Assuming a network with

L

layers of minimal widths

r_1^*, \ldots, r_{L-1}^*

reaches a zero-loss minimum at $ r_1^*! \c ...

2021

Global bifurcation at isolated singular points of the Hadamard derivative

Charles Stuart

Consider F is an element of C(RxX,Y) such that F(lambda, 0) = 0 for all lambda is an element of R, where X and Y are Banach spaces. Bifurcation from the line Rx{0} of trivial solutions is investigated in cases where F(lambda, center dot ) need not be Frech ...

2021

Linear Speedup In Saddle-Point Escape For Decentralized Non-Convex Optimization

Ali H. Sayed, Stefan Vlaski

Under appropriate cooperation protocols and parameter choices, fully decentralized solutions for stochastic optimization have been shown to match the performance of centralized solutions and result in linear speedup (in the number of agents) relative to no ...

IEEE2020

A Catalyst Framework for Minimax Optimization

Negar Kiyavash

We introduce a generic \emph{two-loop} scheme for smooth minimax optimization with strongly-convex-concave objectives. Our approach applies the accelerated proximal point framework (or Catalyst) to the associated \emph{dual problem} and takes full advantag ...

2020

A Catalyst Framework for Minimax Optimization

Negar Kiyavash

We introduce a generic two-loop scheme for smooth minimax optimization with strongly-convex-concave objectives. Our approach applies the accelerated proximal point framework (or Catalyst) to the associated dual problem and takes full advantage of existing ...

NEURAL INFORMATION PROCESSING SYSTEMS (NIPS)2020

A new mechanism for filament disconnection at the X-point: poloidal shear in radial E × B velocity

Federico Nespoli, Davide Galassi

Plasma filaments generated by turbulence in the scrape-off layer are sometimes observed in experi- ments and simulations to disconnect from the target plate in the vicinity of the X-point, resulting in a “quiescent zone” with reduced fluctuations, possibly ...

2020

An Inexact Augmented Lagrangian Framework for Nonconvex Optimization with Nonlinear Constraints

Volkan Cevher, Ahmet Alacaoglu, Armin Eftekhari, Fabian Ricardo Latorre Gomez, Mehmet Fatih Sahin

We propose a practical inexact augmented Lagrangian method (iALM) for nonconvex problems with nonlinear constraints. We characterize the total computational complexity of our method subject to a verifiable geometric condition, which is closely related to t ...

2019

Improved Bounds for Discretization of Langevin Diffusions: Near-Optimal Rates without Convexity

Nicolas Henri Bernard Flammarion

We consider minimizing a nonconvex, smooth function

f

on a Riemannian manifold

\mathcal{M}

. We show that a perturbed version of Riemannian gradient descent algorithm converges to a second-order stationary point (and hence is able to escape saddle point ...

2019

Escaping from saddle points on Riemannian manifolds

Nicolas Henri Bernard Flammarion, Yue Sun

We consider minimizing a nonconvex, smooth function f on a Riemannian manifold M. We show that a perturbed version of Riemannian gradient descent algorithm converges to a second-order stationary point (and hence is able to escape saddle points on the manif ...

2019

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Development of a new method to determine the axial void velocity profile in BWRs from measurements of the in-core neutron noise

Geometry of the Loss Landscape in Overparameterized Neural Networks: Symmetries and Invariances

Global bifurcation at isolated singular points of the Hadamard derivative

Linear Speedup In Saddle-Point Escape For Decentralized Non-Convex Optimization

A Catalyst Framework for Minimax Optimization

A Catalyst Framework for Minimax Optimization

A new mechanism for filament disconnection at the X-point: poloidal shear in radial E × B velocity

An Inexact Augmented Lagrangian Framework for Nonconvex Optimization with Nonlinear Constraints

Improved Bounds for Discretization of Langevin Diffusions: Near-Optimal Rates without Convexity

Escaping from saddle points on Riemannian manifolds

A Catalyst Framework for Minimax Optimization

Development of a new method to determine the axial void velocity profile in BWRs from measurements of the in-core neutron noise

Global bifurcation at isolated singular points of the Hadamard derivative

Geometry of the Loss Landscape in Overparameterized Neural Networks: Symmetries and Invariances

A Catalyst Framework for Minimax Optimization

Linear Speedup In Saddle-Point Escape For Decentralized Non-Convex Optimization

Improved Bounds for Discretization of Langevin Diffusions: Near-Optimal Rates without Convexity

A new mechanism for filament disconnection at the X-point: poloidal shear in radial E × B velocity

An Inexact Augmented Lagrangian Framework for Nonconvex Optimization with Nonlinear Constraints

Escaping from saddle points on Riemannian manifolds