Bifalgorithm post · Brisk · Chapter 1
How can a set be a member of another set?
How can a set be a member of another set? (Brisk · Chapter 1) — "For instance, the set Z of all zebras is a member of R, since Z itself is a set (not a zebra)…
Ideas in this flowchart
- Membership in R depends on whether a set contains itself.
- Z is the set of all zebras.
- Z is itself a set, not a zebra.
- Therefore, Z ∉ Z.
- Consequently, Z ∈ R.
- S is the set of all sets mentioned in this book.
- S contains itself as a member.
- Consequently, S ∉ R.
