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On 06.11.2024 20:08, Jim Burns wrote:On 11/6/2024 11:24 AM, WM wrote:On 06.11.2024 15:22, Jim Burns wrote:On 11/6/2024 5:35 AM, WM wrote:
Is 0 "not in contact with" [-1,0) ⊆ ℝ>>>The intervals are closed with irrational endpoints.>
'Exterior' seems like a good way to say
'not in contact'.
Every point outside is not an endpoint
Yes.
>and is not in contact.>
You don't know that.
From every positive point we know that
it is not 0 and
not in contact with (-oo, 0].
Same for every point not in an interval.
A point can be not.in the closure of eachThe _union_ of>
arbitrarily.many _open_ sets
is an open set.
However,
the _union_ of
these infinitely.many _closed_ intervals
with irrational endpoints
is an open interval
with rational endpoints.
We use only intervals, not limits.
A point is in an interval or it is not.
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