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On an Extension of Hadamard Inequalities for Convex Functions(in English) |
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Citation: |
Wang Zhongli,Wang Xinghua.On an Extension of Hadamard Inequalities for Convex Functions(in English)[J].Chinese Annals of Mathematics B,1982,3(5):567~570 |
Page view: 923
Net amount: 1161 |
Authors: |
Wang Zhongli; Wang Xinghua |
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Abstract: |
设f是区间[a,b]上连续的凸函数,我们证明了Hadamard的不等式
$[f(\frac{{a + b}}{2}) \le \frac{1}{{b - a}}\int_a^b {f(x)dx \le \frac{{f(a) + f(b)}}{2}}$
可以拓广成对[a,b]中任意n+1个点x_0,\cdots,x_n和正数组p_0,\cdots,p_n都成立的下列不等式
$f(\frac{\sum\limits_{i=0}^n p_ix_i}{\sum\limits_{i=0}^n p_i}) \leq |\Omega|^-1 \int_\Omega f(x(t))dt \leq \frac{\sum\limits _{i=0}^n {p_if(x_i)}}{\sum\limits_{i=0}^n p_i}$
式中\Omega是一个包含于n维单位立方体的n维长方体,其重心的第i个坐标为$\sum\limits _{j=i}^n p_j /\sum\limits_{j=i-1}^n p_i$,|\Omega|为\Omega的体积,对\Omega中的任意点$t=(t_1,\cdots,t_n)$,
$w(t)=x_0(1-t_1)+\sum\limits _{i=1}^{n-1} x_i(1-t_{i+1})\prod\limits_{j = 1}^i {{t_j}} +x_n \prod\limits _{j=1}^n t_j$
不等式中两个等号分别成立的情形亦已被分离出来。
此不等式是著名的Jensen 不等式的精密化。 |
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