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试证明: 设f(x)定义在可测集上.若f2(x)在E上可测,且{x∈E:f(x)>0}是可测集,则f(x)在E上可测.
试证明:
设f(x)定义在可测集E上.若f2(x)在E上可测,且{x∈E:f(x)>0}是可测集,则f(x)在E上可测.
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试证明:
设f(x)定义在可测集E上.若f2(x)在E上可测,且{x∈E:f(x)>0}是可测集,则f(x)在E上可测.
设En为可测集列, Ei(f>α)=Ef>α∩Ei,试证:f在E上可测的充要条件是f限制在每个En上均可测,n∈N。