KKM implies Hahn-Banach

Our title means that the Knaster-Kuratowski Mazurkiewicz theorem in 1929 implies the Hahn-Banach theorem. This theorem originated from Hahn in 1926 and Banach in 1929 is of basic importance in the analysis of problems concerning the existence of continuous linear functionals. Its consequences and...

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Main Author: Sehie Park
Format: Article
Language:English
Published: Erdal KARAPINAR 2019-04-01
Series:Results in Nonlinear Analysis
Subjects:
Online Access:https://dergipark.org.tr/en/download/article-file/674940
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author Sehie Park
author_facet Sehie Park
author_sort Sehie Park
collection DOAJ
description Our title means that the Knaster-Kuratowski Mazurkiewicz theorem in 1929 implies the Hahn-Banach theorem. This theorem originated from Hahn in 1926 and Banach in 1929 is of basic importance in the analysis of problems concerning the existence of continuous linear functionals. Its consequences and applications cover hundreds of papers. For a long period, some authors studied the relation of results of the HahnBanach theorem and the Brouwer xed point theorem in 1912 (equivalently, the KKM theorem in 1929). In the present article, we recall some history of such study, and show that the Hahn-Banach theorem can be derived from the KKM theorem and not conversely. Consequently, all consequences and applications of the Hahn-Banach theorem belong to a partial realm of the KKM theory.
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spelling doaj.art-f8c88380b81c4e79bf85bb9d080cef392023-02-15T16:13:34ZengErdal KARAPINARResults in Nonlinear Analysis2636-75562636-75562019-04-0121717KKM implies Hahn-BanachSehie ParkOur title means that the Knaster-Kuratowski Mazurkiewicz theorem in 1929 implies the Hahn-Banach theorem. This theorem originated from Hahn in 1926 and Banach in 1929 is of basic importance in the analysis of problems concerning the existence of continuous linear functionals. Its consequences and applications cover hundreds of papers. For a long period, some authors studied the relation of results of the HahnBanach theorem and the Brouwer xed point theorem in 1912 (equivalently, the KKM theorem in 1929). In the present article, we recall some history of such study, and show that the Hahn-Banach theorem can be derived from the KKM theorem and not conversely. Consequently, all consequences and applications of the Hahn-Banach theorem belong to a partial realm of the KKM theory.https://dergipark.org.tr/en/download/article-file/674940kkm theorykkm theorembrouwer fixed point theoremhahn-banach theorem
spellingShingle Sehie Park
KKM implies Hahn-Banach
Results in Nonlinear Analysis
kkm theory
kkm theorem
brouwer fixed point theorem
hahn-banach theorem
title KKM implies Hahn-Banach
title_full KKM implies Hahn-Banach
title_fullStr KKM implies Hahn-Banach
title_full_unstemmed KKM implies Hahn-Banach
title_short KKM implies Hahn-Banach
title_sort kkm implies hahn banach
topic kkm theory
kkm theorem
brouwer fixed point theorem
hahn-banach theorem
url https://dergipark.org.tr/en/download/article-file/674940
work_keys_str_mv AT sehiepark kkmimplieshahnbanach