じゃあ、何が言えるか書いてみて！ｗ ；ｐ） ＜先制攻撃＞ 下記 ZF＋可算選択公理では、下記 Equivalent ”9. the Axiom of Choice for countable collections of subsets of R.” ”1. in R, a point x is an accumulation point of a subset A iff there exists a sequence in A＼{x} that converges to x,” ”5. R is a Lindel¨ of space,”（リンデレーエフ空間になる） archive.wikiwix.com/cache/display2.php?url=http%3A%2F%2Fwww.emis.de%2Fjournals%2FCMUC%2Fpdf%2Fcmuc9703%2Fherrli.pdf Comment.Math.Univ.Carolin. 38,3(1997)545–552 545 Choice principles in elementary topology and analysis Horst Herrlich
さて ”in R, a point x is an accumulation point of a subset A iff there exists a sequence in A＼{x} that converges to x,” を平たくいえば、a subset A：x0,x1,x2・・・ ,x なる
