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We analyze an adaptive boundary element method for the weakly-singular and hypersingular integral equations for the 2D and 3D Helmholtz problem. The proposed adaptive algorithm is steered by a residual error estimator and does not rely on…

Numerical Analysis · Mathematics 2019-03-21 Alex Bespalov , Timo Betcke , Alexander Haberl , Dirk Praetorius

In this work, we study the rate of convergence of the finite element method for the $p(x)$Laplacian ($1< p_1\leq p(x)\leq p_2\leq 2$) in two dimensional convex domains.

Numerical Analysis · Mathematics 2016-02-22 Leandro M. Del Pezzo , Sandra Martínez

New finite element methods are proposed for elliptic interface problems in one and two dimensions. The main motivation is not only to get an accurate solution but also an accurate first order derivative at the interface (from each side).…

Numerical Analysis · Mathematics 2017-03-02 Fangfang Qin , Zhaohui Wang , Zhijie Ma , Zhilin Li

Bilevel optimization aims to optimize an outer objective function that depends on the solution to an inner optimization problem. It is routinely used in Machine Learning, notably for hyperparameter tuning. The conventional method to compute…

Machine Learning · Computer Science 2024-02-27 Zhenzhang Ye , Gabriel Peyré , Daniel Cremers , Pierre Ablin

We propose and analyze novel adaptive algorithms for the numerical solution of elliptic partial differential equations with parametric uncertainty. Four different marking strategies are employed for refinement of stochastic Galerkin finite…

Numerical Analysis · Mathematics 2019-10-08 Alex Bespalov , Dirk Praetorius , Leonardo Rocchi , Michele Ruggeri

Adaptive Finite Element Method (adaptivity) is known to be an effective numerical tool for some ill-posed problems. The key advantage of the adaptivity is the image improvement with local mesh refinements. A rigorous proof of this property…

Mathematical Physics · Physics 2012-10-30 Larisa Beilina , Michael V. Klibanov

In this paper we make a study of a partial integral differential equation with $p$-Laplacian using a mixed finite element method. Two stable and convergent fixed point schemes are proposed to solve the nonlinear algebraic system. Using the…

Numerical Analysis · Mathematics 2022-03-22 Rui M. P. Almeida , José C. M. Duque , Belchior C. X. Mário

We study the regularity of the solution to an obstacle problem for a class of integro-differential operators. The differential part is a second order elliptic operator, whereas the nonlocal part is given by the integral fractional…

Numerical Analysis · Mathematics 2018-08-07 Andrea Bonito , Wenyu Lei , Abner J. Salgado

In this paper, we develop a numerical method for determining the potential in one and two dimensional fractional Calder\'{o}n problems with a single measurement. Finite difference scheme is employed to discretize the fractional Laplacian,…

Numerical Analysis · Mathematics 2024-09-26 Xinyan Li

The paper considers a class of parametric elliptic partial differential equations (PDEs), where the coefficients and the right-hand side function depend on infinitely many (uncertain) parameters. We introduce a two-level a posteriori…

Numerical Analysis · Mathematics 2021-03-18 Alex Bespalov , Dirk Praetorius , Michele Ruggeri

In this article, we develop a new method to approximate numerically the fractional Laplacian of functions defined on $\mathbb R$, as well as some more general singular integrals. After mapping $\mathbb R$ into a finite interval, we…

Numerical Analysis · Mathematics 2022-12-13 Jorge Cayama , Carlota M. Cuesta , Francisco de la Hoz , Carlos J. Garcia-Cervera

Many problems in modern robotics can be addressed by modeling them as bilevel optimization problems. In this work, we leverage augmented Lagrangian methods and recent advances in automatic differentiation to develop a general-purpose…

Robotics · Computer Science 2019-07-03 Benoit Landry , Zachary Manchester , Marco Pavone

We analyze adaptive mesh-refining algorithms for conforming finite element discretizations of certain non-linear second-order partial differential equations. We allow continuous polynomials of arbitrary, but fixed polynomial order. The…

Numerical Analysis · Mathematics 2014-03-14 Michael Feischl , Thomas Führer , Dirk Praetorius

A numerical scheme is presented for approximating fractional order Poisson problems in two and three dimensions. The scheme is based on reformulating the original problem posed over $\Omega$ on the extruded domain…

Numerical Analysis · Mathematics 2019-05-27 Mark Ainsworth , Christian Glusa

The problem of developing an adaptive isogeometric method (AIGM) for solving elliptic second-order partial differential equations with truncated hierarchical B-splines of arbitrary degree and different order of continuity is addressed. The…

Numerical Analysis · Mathematics 2015-04-21 Annalisa Buffa , Carlotta Giannelli

We study a discretization technique for the parabolic fractional obstacle problem in bounded domains. The fractional Laplacian is realized as the Dirichlet-to-Neumann map for a nonuniformly elliptic equation posed on a semi-infinite…

Numerical Analysis · Mathematics 2015-07-09 Enrique Otarola , Abner J. Salgado

Bilevel optimization is a central tool in machine learning for high-dimensional hyperparameter tuning. Its applications are vast; for instance, in imaging it can be used for learning data-adaptive regularizers and optimizing forward…

Optimization and Control · Mathematics 2025-11-11 Mohammad Sadegh Salehi , Subhadip Mukherjee , Lindon Roberts , Matthias J. Ehrhardt

Multilevel methods are among the most efficient numerical methods for solving large-scale linear systems that arise from discretized partial differential equations. The fundamental module of such methods is a two-level procedure, which…

Numerical Analysis · Mathematics 2021-11-09 Xuefeng Xu

This paper presents a new parameter free partially penalized immersed finite element method and convergence analysis for solving second order elliptic interface problems. A lifting operator is introduced on interface edges to ensure the…

Numerical Analysis · Mathematics 2022-02-23 Haifeng Ji , Feng Wang , Jinru Chen , Zhilin Li

This paper presents an innovative continuous linear finite element approach to effectively solve biharmonic problems on surfaces. The key idea behind this method lies in the strategic utilization of a surface gradient recovery operator to…

Numerical Analysis · Mathematics 2024-04-30 Ying Cai , Hailong Guo , Zhimin Zhang