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In this paper, we study the lower iteration complexity bounds for finding the saddle point of a strongly convex and strongly concave saddle point problem: $\min_x\max_yF(x,y)$. We restrict the classes of algorithms in our investigation to…

Optimization and Control · Mathematics 2021-06-22 Junyu Zhang , Mingyi Hong , Shuzhong Zhang

Anticipating the low energy arrangements of atoms in space is an indispensable scientific task. Modern stochastic approaches to searching for these configurations depend on the optimisation of structures to nearby local minima in the energy…

Materials Science · Physics 2019-02-07 Chris J. Pickard

In constrained reinforcement learning (C-RL), an agent seeks to learn from the environment a policy that maximizes the expected cumulative reward while satisfying minimum requirements in secondary cumulative reward constraints. Several…

Machine Learning · Computer Science 2022-12-06 Tianqi Zheng , Pengcheng You , Enrique Mallada

By means of molecular dynamics simulations, we study the stationary points of the potential energy in a Lennard-Jones liquid, giving a purely geometric characterization of the energy landscape of the system. We find a linear relation…

Statistical Mechanics · Physics 2009-10-31 Kurt Broderix , Kamal K. Bhattacharya , Andrea Cavagna , Annette Zippelius , Irene Giardina

This paper focuses on solving a stochastic saddle point problem (SPP) under an overparameterized regime for the case, when the gradient computation is impractical. As an intermediate step, we generalize Same-sample Stochastic Extra-gradient…

Optimization and Control · Mathematics 2024-06-05 Ekaterina Statkevich , Sofiya Bondar , Darina Dvinskikh , Alexander Gasnikov , Aleksandr Lobanov

Although adversarial examples and model robustness have been extensively studied in the context of linear models and neural networks, research on this issue in tree-based models and how to make tree-based models robust against adversarial…

Machine Learning · Computer Science 2019-06-12 Hongge Chen , Huan Zhang , Duane Boning , Cho-Jui Hsieh

We revisit the smooth convex-concave bilinearly-coupled saddle-point problem of the form $\min_x\max_y f(x) + \langle y,\mathbf{B} x\rangle - g(y)$. In the highly specific case where each of the functions $f(x)$ and $g(y)$ is either affine…

Optimization and Control · Mathematics 2024-11-25 Dmitry Kovalev , Ekaterina Borodich

We consider the case of derivative-free algorithms for non-convex optimization, also known as zero order algorithms, that use only function evaluations rather than gradients. For a wide variety of gradient approximators based on finite…

Optimization and Control · Mathematics 2019-10-30 Lampros Flokas , Emmanouil-Vasileios Vlatakis-Gkaragkounis , Georgios Piliouras

Non-stationary environments are challenging for reinforcement learning algorithms. If the state transition and/or reward functions change based on latent factors, the agent is effectively tasked with optimizing a behavior that maximizes…

Machine Learning · Computer Science 2021-05-21 Lucas N. Alegre , Ana L. C. Bazzan , Bruno C. da Silva

A \emph{saddlepoint} of an $n \times n$ matrix is an entry that is the maximum of its row and the minimum of its column. Saddlepoints give the \emph{value} of a two-player zero-sum game, corresponding to its pure-strategy Nash equilibria;…

Computational Complexity · Computer Science 2024-01-17 Justin Dallant , Frederik Haagensen , Riko Jacob , László Kozma , Sebastian Wild

A computational framework is presented for the sampling of the energy surface of magnetic systems via the systematic identification of first-order saddle points that determine connectivity of metastable states and define the mechanisms of…

Materials Science · Physics 2025-12-09 Hendrik Schrautzer , Tim Drevelow , Hannes Jónsson , Pavel F. Bessarab

Weak constraint four-dimensional variational data assimilation is an important method for incorporating data (typically observations) into a model. The linearised system arising within the minimisation process can be formulated as a saddle…

Numerical Analysis · Mathematics 2018-02-14 Melina A. Freitag , Daniel L. H. Green

We study the asymptotic behavior of second-order algorithms mixing Newton's method and inertial gradient descent in non-convex landscapes. We show that, despite the Newtonian behavior of these methods, they almost always escape strict…

Optimization and Control · Mathematics 2024-02-13 Camille Castera

The diffusion strategy for distributed learning from streaming data employs local stochastic gradient updates along with exchange of iterates over neighborhoods. In Part I [2] of this work we established that agents cluster around a network…

Multiagent Systems · Computer Science 2019-07-04 Stefan Vlaski , Ali H. Sayed

An autonomous robot with a limited vision range finds a path to the goal in an unknown environment in 2D avoiding polygonal obstacles. In the process of discovering the environmental map, the robot has to return to some positions marked…

Robotics · Computer Science 2023-12-19 Phan Thanh An , Nguyen Thi Le

In this paper, we study the gradient descent-ascent method for convex-concave saddle-point problems. We derive a new non-asymptotic global convergence rate in terms of distance to the solution set by using the semidefinite programming…

Optimization and Control · Mathematics 2022-09-19 Moslem Zamani , Hadi Abbaszadehpeivasti , Etienne de Klerk

We consider the problem of computing optimal policies in average-reward Markov decision processes. This classical problem can be formulated as a linear program directly amenable to saddle-point optimization methods, albeit with a number of…

Optimization and Control · Mathematics 2020-01-13 Joan Bas-Serrano , Gergely Neu

The properties of higher-index saddle points have been invoked in recent theories of the dynamics of supercooled liquids. Here we examine in detail a mapping of configurations to saddle points using minimization of $|\nabla E|^2$, which has…

Disordered Systems and Neural Networks · Physics 2007-05-23 Jonathan P. K. Doye , David J. Wales

We introduce a new stochastic algorithm to locate the index-1 saddle points of a function $V:\mathbb R^d \to \mathbb R$, with $d$ possibly large. This algorithm can be seen as an equivalent of the stochastic gradient descent which is a…

Numerical Analysis · Mathematics 2023-08-24 Tony Lelièvre , Panos Parpas

A major approach to saddle point optimization $\min_x\max_y f(x, y)$ is a gradient based approach as is popularized by generative adversarial networks (GANs). In contrast, we analyze an alternative approach relying only on an oracle that…

Optimization and Control · Mathematics 2021-04-02 Youhei Akimoto