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Real Analysis, Stein Theorem 4.3前面说| We may now go one step further, and approximate by step functions. Here, in general, the convergence may hold only almost everywhere. |
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能不能举一个例子 $f$ 不能处处被阶梯函数逼近.
dirichlet function $\mathbf 1_{\mathbb Q}$是简单函数不是阶梯函数. 它应该不能处处被阶梯函数逼近吧
另外There exists a sequence of step functions...能不能加强为There exists an increasing sequence of step functions... |
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