Ok, with help on another forum, I understood what was going on.
Hello
I'm having trouble understanding something in Munkre's topology book. It's exercise 20.6.(a).
It says: Let be the uniform metric on . Given and given , let .
(a) Show that is different from the -ball
Now, I found a solution to this exercise that said that the point belonged to U, but not to the ball. How so?
Thanks