Existence of maximal and minimal weak solutions and finite difference approximations for elliptic systems with nonlinear boundary conditions

We establish the existence of maximal and minimal weak solutions between ordered pairs of weak sub- and super-solutions for a coupled system of elliptic equations with quasimonotone nonlinearities on the boundary. We also formulate a finite difference method to approximate the solutions and est...

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Main Authors: Shalmali Bandyopadhyay, Thomas Lewis, Nsoki Mavinga
Format: Article
Language:English
Published: Texas State University 2025-04-01
Series:Electronic Journal of Differential Equations
Subjects:
Online Access:http://ejde.math.txstate.edu/Volumes/2025/43/abstr.html
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author Shalmali Bandyopadhyay
Thomas Lewis
Nsoki Mavinga
author_facet Shalmali Bandyopadhyay
Thomas Lewis
Nsoki Mavinga
author_sort Shalmali Bandyopadhyay
collection DOAJ
description We establish the existence of maximal and minimal weak solutions between ordered pairs of weak sub- and super-solutions for a coupled system of elliptic equations with quasimonotone nonlinearities on the boundary. We also formulate a finite difference method to approximate the solutions and establish the existence of maximal and minimal approximations between ordered pairs of discrete sub- and super-solutions. Monotone iterations are formulated for constructing the maximal and minimal solutions when the nonlinearity is monotone. Numerical simulations are used to explore existence, nonexistence, uniqueness and non-uniqueness properties of positive solutions. When the nonlinearities do not satisfy the monotonicity condition, we prove the existence of weak maximal and minimal solutions using Zorn’s lemma and a version of Kato’s inequality up to the boundary.
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series Electronic Journal of Differential Equations
spelling doaj-art-b5b58f6f8e7f4a619e3d7ba1a3b184532025-08-20T03:43:40ZengTexas State UniversityElectronic Journal of Differential Equations1072-66912025-04-01202543,121Existence of maximal and minimal weak solutions and finite difference approximations for elliptic systems with nonlinear boundary conditionsShalmali Bandyopadhyay0Thomas Lewis1Nsoki Mavinga2 Univ. of Tennessee, Martin, TN, USA The Univ. of North Carolina, Greensboro, NC, USA Swarthmore College, Swarthmore, PA, USA We establish the existence of maximal and minimal weak solutions between ordered pairs of weak sub- and super-solutions for a coupled system of elliptic equations with quasimonotone nonlinearities on the boundary. We also formulate a finite difference method to approximate the solutions and establish the existence of maximal and minimal approximations between ordered pairs of discrete sub- and super-solutions. Monotone iterations are formulated for constructing the maximal and minimal solutions when the nonlinearity is monotone. Numerical simulations are used to explore existence, nonexistence, uniqueness and non-uniqueness properties of positive solutions. When the nonlinearities do not satisfy the monotonicity condition, we prove the existence of weak maximal and minimal solutions using Zorn’s lemma and a version of Kato’s inequality up to the boundary.http://ejde.math.txstate.edu/Volumes/2025/43/abstr.htmlweak solutionsquasimonotonesubsolutionsupersolutionzorn's lemmafinite difference methodkato's inequality
spellingShingle Shalmali Bandyopadhyay
Thomas Lewis
Nsoki Mavinga
Existence of maximal and minimal weak solutions and finite difference approximations for elliptic systems with nonlinear boundary conditions
Electronic Journal of Differential Equations
weak solutions
quasimonotone
subsolution
supersolution
zorn's lemma
finite difference method
kato's inequality
title Existence of maximal and minimal weak solutions and finite difference approximations for elliptic systems with nonlinear boundary conditions
title_full Existence of maximal and minimal weak solutions and finite difference approximations for elliptic systems with nonlinear boundary conditions
title_fullStr Existence of maximal and minimal weak solutions and finite difference approximations for elliptic systems with nonlinear boundary conditions
title_full_unstemmed Existence of maximal and minimal weak solutions and finite difference approximations for elliptic systems with nonlinear boundary conditions
title_short Existence of maximal and minimal weak solutions and finite difference approximations for elliptic systems with nonlinear boundary conditions
title_sort existence of maximal and minimal weak solutions and finite difference approximations for elliptic systems with nonlinear boundary conditions
topic weak solutions
quasimonotone
subsolution
supersolution
zorn's lemma
finite difference method
kato's inequality
url http://ejde.math.txstate.edu/Volumes/2025/43/abstr.html
work_keys_str_mv AT shalmalibandyopadhyay existenceofmaximalandminimalweaksolutionsandfinitedifferenceapproximationsforellipticsystemswithnonlinearboundaryconditions
AT thomaslewis existenceofmaximalandminimalweaksolutionsandfinitedifferenceapproximationsforellipticsystemswithnonlinearboundaryconditions
AT nsokimavinga existenceofmaximalandminimalweaksolutionsandfinitedifferenceapproximationsforellipticsystemswithnonlinearboundaryconditions