On the Weierstrass Theorem on extrema and its application for finding fixed points and zeros of mappings

In this paper, we examine the applicability of the Lagrange Multiplier Rule, specifically the Karush–Kuhn–Tucker Theorem, to investigate the existence of fixed points and zeros of certain potential mappings between finite and infinite spaces. Such zeros are investigated as constrained extrema, whose...

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Main Author: Marek Galewski
Format: Article
Language:English
Published: World Scientific Publishing 2025-08-01
Series:Bulletin of Mathematical Sciences
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Online Access:https://www.worldscientific.com/doi/10.1142/S1664360725500031
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author Marek Galewski
author_facet Marek Galewski
author_sort Marek Galewski
collection DOAJ
description In this paper, we examine the applicability of the Lagrange Multiplier Rule, specifically the Karush–Kuhn–Tucker Theorem, to investigate the existence of fixed points and zeros of certain potential mappings between finite and infinite spaces. Such zeros are investigated as constrained extrema, whose existence is established via the Weierstrass Theorem. By assuming the potentiality of the operator, we are able to relax the required invariance conditions. The paper is divided into two parts. In the first part, we provide simple proofs of the Lagrange Multiplier Rule and the Karush–Kuhn–Tucker Theorem in some special cases. In the second part, these results are used to investigate potential counterparts of several known theorems, such as the Brouwer Fixed Point Theorem and the Schauder Fixed Point Theorem.
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spelling doaj-art-36f09b68fc184fb0b7223a6799e672ae2025-08-22T07:46:40ZengWorld Scientific PublishingBulletin of Mathematical Sciences1664-36071664-36152025-08-01150210.1142/S1664360725500031On the Weierstrass Theorem on extrema and its application for finding fixed points and zeros of mappingsMarek Galewski0Institute of Mathematics, Lodz University of Technology, Al. Politechniki 8, 93-590 Lodz, PolandIn this paper, we examine the applicability of the Lagrange Multiplier Rule, specifically the Karush–Kuhn–Tucker Theorem, to investigate the existence of fixed points and zeros of certain potential mappings between finite and infinite spaces. Such zeros are investigated as constrained extrema, whose existence is established via the Weierstrass Theorem. By assuming the potentiality of the operator, we are able to relax the required invariance conditions. The paper is divided into two parts. In the first part, we provide simple proofs of the Lagrange Multiplier Rule and the Karush–Kuhn–Tucker Theorem in some special cases. In the second part, these results are used to investigate potential counterparts of several known theorems, such as the Brouwer Fixed Point Theorem and the Schauder Fixed Point Theorem.https://www.worldscientific.com/doi/10.1142/S1664360725500031Lagrange multiplier ruleKuhn–Tucker theoremSchauder theoremBrouwer lemmaKrasnoselskii theorem
spellingShingle Marek Galewski
On the Weierstrass Theorem on extrema and its application for finding fixed points and zeros of mappings
Bulletin of Mathematical Sciences
Lagrange multiplier rule
Kuhn–Tucker theorem
Schauder theorem
Brouwer lemma
Krasnoselskii theorem
title On the Weierstrass Theorem on extrema and its application for finding fixed points and zeros of mappings
title_full On the Weierstrass Theorem on extrema and its application for finding fixed points and zeros of mappings
title_fullStr On the Weierstrass Theorem on extrema and its application for finding fixed points and zeros of mappings
title_full_unstemmed On the Weierstrass Theorem on extrema and its application for finding fixed points and zeros of mappings
title_short On the Weierstrass Theorem on extrema and its application for finding fixed points and zeros of mappings
title_sort on the weierstrass theorem on extrema and its application for finding fixed points and zeros of mappings
topic Lagrange multiplier rule
Kuhn–Tucker theorem
Schauder theorem
Brouwer lemma
Krasnoselskii theorem
url https://www.worldscientific.com/doi/10.1142/S1664360725500031
work_keys_str_mv AT marekgalewski ontheweierstrasstheoremonextremaanditsapplicationforfindingfixedpointsandzerosofmappings