{"title":"利用矩阵Cauchy-Schwarz不等式证明Lee关于Frobenius范数的猜想","authors":"Teng Zhang","doi":"10.1016/j.laa.2025.07.017","DOIUrl":null,"url":null,"abstract":"<div><div>In 2010, Eun-Young Lee conjectured that if <span><math><mi>A</mi><mo>,</mo><mi>B</mi></math></span> are two <span><math><mi>n</mi><mo>×</mo><mi>n</mi></math></span> complex matrices and <span><math><mrow><mo>|</mo><mi>A</mi><mo>|</mo></mrow><mo>,</mo><mrow><mo>|</mo><mi>B</mi><mo>|</mo></mrow></math></span> are the absolute values of <span><math><mi>A</mi><mo>,</mo><mi>B</mi></math></span>, respectively, then<span><span><span><math><msub><mrow><mo>‖</mo><mi>A</mi><mo>+</mo><mi>B</mi><mo>‖</mo></mrow><mrow><mi>F</mi></mrow></msub><mo>≤</mo><msqrt><mrow><mfrac><mrow><mn>1</mn><mo>+</mo><msqrt><mrow><mn>2</mn></mrow></msqrt></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></msqrt><msub><mrow><mo>‖</mo><mrow><mo>|</mo><mi>A</mi><mo>|</mo></mrow><mo>+</mo><mrow><mo>|</mo><mi>B</mi><mo>|</mo></mrow><mo>‖</mo></mrow><mrow><mi>F</mi></mrow></msub><mo>,</mo></math></span></span></span> where <span><math><msub><mrow><mo>‖</mo><mo>⋅</mo><mo>‖</mo></mrow><mrow><mi>F</mi></mrow></msub></math></span> is the Frobenius norm of matrices. This conjecture has been proven by Lin and Zhang (2022) <span><span>[3]</span></span> by studying inequalities for the angle between two matrices induced by the Frobenius inner product. In this paper, we present a new proof of the same result, relying solely on the Cauchy-Schwarz inequality.</div></div>","PeriodicalId":18043,"journal":{"name":"Linear Algebra and its Applications","volume":"725 ","pages":"Pages 355-358"},"PeriodicalIF":1.1000,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"A new proof of Lee's conjecture on the Frobenius norm via the matrix Cauchy-Schwarz inequality\",\"authors\":\"Teng Zhang\",\"doi\":\"10.1016/j.laa.2025.07.017\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>In 2010, Eun-Young Lee conjectured that if <span><math><mi>A</mi><mo>,</mo><mi>B</mi></math></span> are two <span><math><mi>n</mi><mo>×</mo><mi>n</mi></math></span> complex matrices and <span><math><mrow><mo>|</mo><mi>A</mi><mo>|</mo></mrow><mo>,</mo><mrow><mo>|</mo><mi>B</mi><mo>|</mo></mrow></math></span> are the absolute values of <span><math><mi>A</mi><mo>,</mo><mi>B</mi></math></span>, respectively, then<span><span><span><math><msub><mrow><mo>‖</mo><mi>A</mi><mo>+</mo><mi>B</mi><mo>‖</mo></mrow><mrow><mi>F</mi></mrow></msub><mo>≤</mo><msqrt><mrow><mfrac><mrow><mn>1</mn><mo>+</mo><msqrt><mrow><mn>2</mn></mrow></msqrt></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></msqrt><msub><mrow><mo>‖</mo><mrow><mo>|</mo><mi>A</mi><mo>|</mo></mrow><mo>+</mo><mrow><mo>|</mo><mi>B</mi><mo>|</mo></mrow><mo>‖</mo></mrow><mrow><mi>F</mi></mrow></msub><mo>,</mo></math></span></span></span> where <span><math><msub><mrow><mo>‖</mo><mo>⋅</mo><mo>‖</mo></mrow><mrow><mi>F</mi></mrow></msub></math></span> is the Frobenius norm of matrices. This conjecture has been proven by Lin and Zhang (2022) <span><span>[3]</span></span> by studying inequalities for the angle between two matrices induced by the Frobenius inner product. In this paper, we present a new proof of the same result, relying solely on the Cauchy-Schwarz inequality.</div></div>\",\"PeriodicalId\":18043,\"journal\":{\"name\":\"Linear Algebra and its Applications\",\"volume\":\"725 \",\"pages\":\"Pages 355-358\"},\"PeriodicalIF\":1.1000,\"publicationDate\":\"2025-07-18\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Linear Algebra and its Applications\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0024379525003015\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Linear Algebra and its Applications","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0024379525003015","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATHEMATICS","Score":null,"Total":0}
A new proof of Lee's conjecture on the Frobenius norm via the matrix Cauchy-Schwarz inequality
In 2010, Eun-Young Lee conjectured that if are two complex matrices and are the absolute values of , respectively, then where is the Frobenius norm of matrices. This conjecture has been proven by Lin and Zhang (2022) [3] by studying inequalities for the angle between two matrices induced by the Frobenius inner product. In this paper, we present a new proof of the same result, relying solely on the Cauchy-Schwarz inequality.
期刊介绍:
Linear Algebra and its Applications publishes articles that contribute new information or new insights to matrix theory and finite dimensional linear algebra in their algebraic, arithmetic, combinatorial, geometric, or numerical aspects. It also publishes articles that give significant applications of matrix theory or linear algebra to other branches of mathematics and to other sciences. Articles that provide new information or perspectives on the historical development of matrix theory and linear algebra are also welcome. Expository articles which can serve as an introduction to a subject for workers in related areas and which bring one to the frontiers of research are encouraged. Reviews of books are published occasionally as are conference reports that provide an historical record of major meetings on matrix theory and linear algebra.