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## Main Question or Discussion Point

What's the difference between those assertions:

" A set X is both open and closed."

and

" A set X is neither open nor closed."

For the first, I knew some examples: The real line itself, and the empty set.

But what example can be araised about the second?

And any better ones to the former?

Thx.

" A set X is both open and closed."

and

" A set X is neither open nor closed."

For the first, I knew some examples: The real line itself, and the empty set.

But what example can be araised about the second?

And any better ones to the former?

Thx.