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elim不讲数理,胡搅蛮缠的无赖本质。该主题主帖生吞正则公理,活剥极限集定义,仍冥顽不化地坚持其“臭便”思想。事实上根据elim自己给出的集列\(\{A_n:=\{m∈N:m>n\}\}\)定义,集列\(\{A_n^c=\{m∈N:m≤n\}\}\)单调递增,根据周民强《实变函数论》定义1.9,我们有\(\displaystyle\bigcup_{k=1}^∞ A_k^c\color{red}{=}\)\((\displaystyle\lim_{k→∞} A_k)^c\).(注意红色的等号是等式演译,若两边取补则得恒等式\(\displaystyle\lim_{k→∞} A_k\color{red}{\equiv}\)\(\displaystyle\lim_{k→∞} A_k\)!根据elim集列\(\{A_n:=\{m∈N:m>n\}\}\)的定义\(\forall A_m^c\subset\displaystyle\bigcup_{k=1}^∞ A_k^c\)都恒有\(\displaystyle\lim_{n→∞}\{n+1,n+2……\}\)与之对应。所以根据周民强定义1.9, 极限集\(\displaystyle\bigcup_{k=}^∞ A_k=\displaystyle\bigcap_{k=1}^∞ A_k=\)\(\displaystyle\lim_{n→∞}\{n+1,n+2,……\}\)(集合交并运算吸收律:\(A\cap A=A;A\cup A=A\)).所以\(\overline{\overline{\displaystyle\bigcap_{k=1}^∞ A_k^c}}=\)\(\overline{\overline{\displaystyle\lim_{k→∞}\{n+1,n+2,…\}}}\)l所以\(N_∞=\displaystyle\lim_{n→∞}\{n+1,n+2,……\}≠\phi\)
elim仅仅根据\(\displaystyle\bigcup_{k=1}^∞ A_k^c=\mathbb{N}^+\)就判定\(\displaystyle\lim_{k→∞} A_n=\phi\)\(\color{red}{是反数学的}\). 如集合\(\mathscr{A}_k=\{x:x=(k+1)^2,k∈N\}\)(准伽利略猜想)便有\(\displaystyle\bigcup_{k=1}^∞\mathscr{A}_k^c=N\)但\(\displaystyle\lim_{n→∞}\mathscr{A}≠\phi\)再者因为\(\displaystyle\lim_{k→∞}\{n+1,n+2,……,\}\)中的成员\(\displaystyle\lim_{n→∞}(n+j,j∈N\)的存在性是由Peano axioms或Cantor第一生成原则唯一确定的。\(\displaystyle\lim_{n→∞}(n+j,j∈N\)在方嘉琳《集合论》中叫超限数,在Cantor《超穷数理论基础》中叫超穷正整数,两书该把它记为\(ω+j\)。因此elim说\(N_∞=\displaystyle\lim_{k→∞}\{n+1,n+2,…\}=\phi\)\(\color{red}{是反数学的!}\) |
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