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本帖最后由 elim 于 2024-7-4 20:31 编辑
孬种先确定能理解并接受以下谓词演算,再来提问。否则对牛弹琴的事我不干.
\(\color{red}{\forall m\in\mathbb{N}\,\big(m\in A_m^c\subset \displaystyle\big(\bigcup_{n=1}^\infty A_n^c\big)\subset\mathbb{N}\big)\implies\big(\bigcup_{n=1}^\infty A_n^c=\mathbb{N}\big)\overset{\text{DeMogan}}\implies (H_{\infty}=\varnothing)}\)
【定理】\(\forall B\subseteq\mathbb{N}\,\big(B\cap\displaystyle\bigcup_{n=1}^\infty A_n^c=B\big)\)
【证明】\(\because\;\forall m\in\mathbb{N}\,\big(\{m\}\subset A_m^c\subset\displaystyle\bigcup_{n=1}^\infty A_n^c\big)\)
\(\therefore\;\forall m\in\mathbb{N}\,\big(\{m\}\cap\displaystyle\bigcup_{n=1}^\infty A_n^c=\{m\}\big)\)
\(\therefore\;\;\forall B\subseteq\mathbb{N}:\;\displaystyle B\cap\bigcup_{n=1}^\infty A_n^c=\big(\bigcup_{m\in B}\{m\}\big)\cap\bigcup_{n=1}^\infty A_n^c\)
\(\qquad\displaystyle=\bigcup_{m\in B}\big(\{m\}\cap\displaystyle\bigcup_{n=1}^\infty A_n^c\big)=\bigcup_{m\in B}\{m\}=B.\quad\square\)
上定理指出:非空亦空是孬种的痴心妄想. 无论孬种咋样扯,
它仍是个不懂集论的蠢东西
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