Similar to 閉集合

(55636) 2002 TX300

(55637) 2002 UX25

55th Division (Imperial Japanese Army)

101st SS Heavy Panzer Battalion

Open set

Topological indistinguishability

Separated sets

0

1

2

3

4

5

6

7

8

9

Mathematics

0.999...

Zero to the power of zero

One-dimensional space

1 + 2 + 3 + 4 + ⋯

1 + 2 + 4 + 8 + ⋯