7楼: Originally posted by mathematic at 2015-12-07 22:17:33
因半集代数S中并运算不封闭，从而虽然\{A_n\}_{n=1}^{+\infty}\subset S ，但\sum_{n=1}^{+\infty}A_n不一定属于半集代数S，因此\mu(\sum_{n=1}^{+\infty}A_n)无意义。可数可加性使用不了的。...

2楼: Originally posted by junefi at 2015-12-06 09:22:41
这道有意思基础题被淹没了。
证明第一个不等号：
Let \sup{E_1}(A)=\alpha, then for any \varepsilon>0, there exists {B_n} and \bigcup\limits_n {{B_n}}  \subset A such that
\alpha  - \varepsilon  & ...

2楼: Originally posted by junefi at 2015-12-06 09:22:41
这道有意思基础题被淹没了。
证明第一个不等号：
Let \sup{E_1}(A)=\alpha, then for any \varepsilon>0, there exists {B_n} and \bigcup\limits_n {{B_n}}  \subset A such that
\alpha  - \varepsilon  & ...