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Lebl-Basic-Analysis-I
· Problem 7.4.2
Metric Spaces
Mathematics · compactness
Problem
Let
A
≔
{
1
/
n
:
n
∈
N
}
⊂
R
A \colonequals \{1/n : n \in \mathbb{N}\} \subset \mathbb{R}
A
:
=
{
1/
n
:
n
∈
N
}
⊂
R
. a) Show that
A
A
A
is not compact directly using the definition. b) Show that
A
∪
{
0
}
A \cup \{0\}
A
∪
{
0
}
is compact directly using the definition.
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