{"title":"Lebesgue定理与Baire刻画定理的等价性","authors":"Jonald P. Fenecios, A. Racca","doi":"10.22342/jims.28.2.1064.158-163","DOIUrl":null,"url":null,"abstract":"Let $X$ be a complete separable metric space and $Y$ be a separable Banach space. We provide a proof of equivalence by linking explicitly the following statements:\\\\ \\noindent \\textbf{\\textit{Lebesgue's Theorem.}} For every $\\epsilon>0$ there exists a countable collection of closed sets $\\left\\lbrace C_n\\right\\rbrace $ of $X$ such that $$X=\\bigcup_{n=1}^{\\infty}C_n\\;\\;\\text{and}\\;\\; \\omega_f\\left( C_n\\right)<\\epsilon\\;\\; \\text{for each} \\;\\; n.$$ \\textbf{\\textit{Baire Characterization Theorem.}} For every nonempty perfect set $K\\subset X$, the function $f|_K$ has at least one point of continuity in $K$. In fact, $C(f|_K)$ is dense in $K$.\\\\ \\indent Moreover, replacing ``closed'' by ``open'' in the Lebesgue's Theorem, we obtain a characterization of continuous functions on space $X$.","PeriodicalId":42206,"journal":{"name":"Journal of the Indonesian Mathematical Society","volume":" ","pages":""},"PeriodicalIF":0.3000,"publicationDate":"2022-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Equivalence of Lebesgue's Theorem and Baire Characterization Theorem\",\"authors\":\"Jonald P. Fenecios, A. Racca\",\"doi\":\"10.22342/jims.28.2.1064.158-163\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Let $X$ be a complete separable metric space and $Y$ be a separable Banach space. We provide a proof of equivalence by linking explicitly the following statements:\\\\\\\\ \\\\noindent \\\\textbf{\\\\textit{Lebesgue's Theorem.}} For every $\\\\epsilon>0$ there exists a countable collection of closed sets $\\\\left\\\\lbrace C_n\\\\right\\\\rbrace $ of $X$ such that $$X=\\\\bigcup_{n=1}^{\\\\infty}C_n\\\\;\\\\;\\\\text{and}\\\\;\\\\; \\\\omega_f\\\\left( C_n\\\\right)<\\\\epsilon\\\\;\\\\; \\\\text{for each} \\\\;\\\\; n.$$ \\\\textbf{\\\\textit{Baire Characterization Theorem.}} For every nonempty perfect set $K\\\\subset X$, the function $f|_K$ has at least one point of continuity in $K$. In fact, $C(f|_K)$ is dense in $K$.\\\\\\\\ \\\\indent Moreover, replacing ``closed'' by ``open'' in the Lebesgue's Theorem, we obtain a characterization of continuous functions on space $X$.\",\"PeriodicalId\":42206,\"journal\":{\"name\":\"Journal of the Indonesian Mathematical Society\",\"volume\":\" \",\"pages\":\"\"},\"PeriodicalIF\":0.3000,\"publicationDate\":\"2022-07-30\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of the Indonesian Mathematical Society\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.22342/jims.28.2.1064.158-163\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q4\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the Indonesian Mathematical Society","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.22342/jims.28.2.1064.158-163","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"MATHEMATICS","Score":null,"Total":0}
Equivalence of Lebesgue's Theorem and Baire Characterization Theorem
Let $X$ be a complete separable metric space and $Y$ be a separable Banach space. We provide a proof of equivalence by linking explicitly the following statements:\\ \noindent \textbf{\textit{Lebesgue's Theorem.}} For every $\epsilon>0$ there exists a countable collection of closed sets $\left\lbrace C_n\right\rbrace $ of $X$ such that $$X=\bigcup_{n=1}^{\infty}C_n\;\;\text{and}\;\; \omega_f\left( C_n\right)<\epsilon\;\; \text{for each} \;\; n.$$ \textbf{\textit{Baire Characterization Theorem.}} For every nonempty perfect set $K\subset X$, the function $f|_K$ has at least one point of continuity in $K$. In fact, $C(f|_K)$ is dense in $K$.\\ \indent Moreover, replacing ``closed'' by ``open'' in the Lebesgue's Theorem, we obtain a characterization of continuous functions on space $X$.