- #1
elias001
- 12
- 0
Homework Statement
let d be a metric on an infinite set m. Prove that there is an open set u in m such that both u amd its complements are infinite.
Homework Equations
If d is not a discrete metric, and M is an infinite set (uncountble), then we can always form an denumerable subset (countably infinite).
My question is i don't know how to find an open subset for a given radius delta. I know how to do it if d is a discrete metric and M is a countably infinite set.
Thanks in advance