なぜ悪質な永久機関ビジネスはなくならないのか?4at SCIなぜ悪質な永久機関ビジネスはなくならないのか?4
- 暇つぶし2ch360:ご冗談でしょう?名無しさん 13/08/15 NY:AN:NY.AN FbF1TtLN >>310 >> Thus in ZF there is no set of all sets, nor any Russell set {x | not(x ∈ x)} (which >> would be universal since ∀x(not x ∈ x) holds in ZF).