Stability of Bi-Additive Mappings and Bi-Jensen Mappings

Symmetry is repetitive self-similarity. We proved the stability problem by replicating the well-known Cauchy equation and the well-known Jensen equation into two variables. In this paper, we proved the Hyers-Ulam stability of the bi-additive functional equation <inline-formula><math xmlns=&...

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Main Authors: Jae-Hyeong Bae, Won-Gil Park
Format: Article
Language:English
Published: MDPI AG 2021-06-01
Series:Symmetry
Subjects:
Online Access:https://www.mdpi.com/2073-8994/13/7/1180
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author Jae-Hyeong Bae
Won-Gil Park
author_facet Jae-Hyeong Bae
Won-Gil Park
author_sort Jae-Hyeong Bae
collection DOAJ
description Symmetry is repetitive self-similarity. We proved the stability problem by replicating the well-known Cauchy equation and the well-known Jensen equation into two variables. In this paper, we proved the Hyers-Ulam stability of the bi-additive functional equation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mo>(</mo><mi>x</mi><mo>+</mo><mi>y</mi><mo>,</mo><mi>z</mi><mo>+</mo><mi>w</mi><mo>)</mo><mo>=</mo><mi>f</mi><mo>(</mo><mi>x</mi><mo>,</mo><mi>z</mi><mo>)</mo><mo>+</mo><mi>f</mi><mo>(</mo><mi>y</mi><mo>,</mo><mi>w</mi><mo>)</mo></mrow></semantics></math></inline-formula> and the bi-Jensen functional equation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>4</mn><mi>f</mi><mfenced separators="" open="(" close=")"><mfrac><mrow><mi>x</mi><mo>+</mo><mi>y</mi></mrow><mn>2</mn></mfrac><mo>,</mo><mspace width="0.166667em"></mspace><mfrac><mrow><mi>z</mi><mo>+</mo><mi>w</mi></mrow><mn>2</mn></mfrac></mfenced><mo>=</mo><mi>f</mi><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mspace width="0.166667em"></mspace><mi>z</mi><mo>)</mo></mrow><mo>+</mo><mi>f</mi><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mspace width="0.166667em"></mspace><mi>w</mi><mo>)</mo></mrow><mo>+</mo><mi>f</mi><mrow><mo>(</mo><mi>y</mi><mo>,</mo><mspace width="0.166667em"></mspace><mi>z</mi><mo>)</mo></mrow><mo>+</mo><mi>f</mi><mrow><mo>(</mo><mi>y</mi><mo>,</mo><mspace width="0.166667em"></mspace><mi>w</mi><mo>)</mo></mrow><mo>.</mo></mrow></semantics></math></inline-formula>
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spelling doaj.art-a0a7a7cd15204374a854840b430e15582023-11-22T02:21:20ZengMDPI AGSymmetry2073-89942021-06-01137118010.3390/sym13071180Stability of Bi-Additive Mappings and Bi-Jensen MappingsJae-Hyeong Bae0Won-Gil Park1Humanitas College, Kyung Hee University, Yongin 17104, KoreaDepartment of Mathematics Education, College of Education, Mokwon University, Daejeon 35349, KoreaSymmetry is repetitive self-similarity. We proved the stability problem by replicating the well-known Cauchy equation and the well-known Jensen equation into two variables. In this paper, we proved the Hyers-Ulam stability of the bi-additive functional equation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mo>(</mo><mi>x</mi><mo>+</mo><mi>y</mi><mo>,</mo><mi>z</mi><mo>+</mo><mi>w</mi><mo>)</mo><mo>=</mo><mi>f</mi><mo>(</mo><mi>x</mi><mo>,</mo><mi>z</mi><mo>)</mo><mo>+</mo><mi>f</mi><mo>(</mo><mi>y</mi><mo>,</mo><mi>w</mi><mo>)</mo></mrow></semantics></math></inline-formula> and the bi-Jensen functional equation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>4</mn><mi>f</mi><mfenced separators="" open="(" close=")"><mfrac><mrow><mi>x</mi><mo>+</mo><mi>y</mi></mrow><mn>2</mn></mfrac><mo>,</mo><mspace width="0.166667em"></mspace><mfrac><mrow><mi>z</mi><mo>+</mo><mi>w</mi></mrow><mn>2</mn></mfrac></mfenced><mo>=</mo><mi>f</mi><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mspace width="0.166667em"></mspace><mi>z</mi><mo>)</mo></mrow><mo>+</mo><mi>f</mi><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mspace width="0.166667em"></mspace><mi>w</mi><mo>)</mo></mrow><mo>+</mo><mi>f</mi><mrow><mo>(</mo><mi>y</mi><mo>,</mo><mspace width="0.166667em"></mspace><mi>z</mi><mo>)</mo></mrow><mo>+</mo><mi>f</mi><mrow><mo>(</mo><mi>y</mi><mo>,</mo><mspace width="0.166667em"></mspace><mi>w</mi><mo>)</mo></mrow><mo>.</mo></mrow></semantics></math></inline-formula>https://www.mdpi.com/2073-8994/13/7/1180stabilitybi-additive mappingbi-Jensen mapping
spellingShingle Jae-Hyeong Bae
Won-Gil Park
Stability of Bi-Additive Mappings and Bi-Jensen Mappings
Symmetry
stability
bi-additive mapping
bi-Jensen mapping
title Stability of Bi-Additive Mappings and Bi-Jensen Mappings
title_full Stability of Bi-Additive Mappings and Bi-Jensen Mappings
title_fullStr Stability of Bi-Additive Mappings and Bi-Jensen Mappings
title_full_unstemmed Stability of Bi-Additive Mappings and Bi-Jensen Mappings
title_short Stability of Bi-Additive Mappings and Bi-Jensen Mappings
title_sort stability of bi additive mappings and bi jensen mappings
topic stability
bi-additive mapping
bi-Jensen mapping
url https://www.mdpi.com/2073-8994/13/7/1180
work_keys_str_mv AT jaehyeongbae stabilityofbiadditivemappingsandbijensenmappings
AT wongilpark stabilityofbiadditivemappingsandbijensenmappings