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Basic Analysis I — Real Analysis
· Problem 7.1.11
Metric Spaces — Jiri Lebl
Mathematics — Real Analysis · metric-spaces
Problem
a) Find a metric
d
d
d
on
N
\mathbb{N}
N
such that
N
\mathbb{N}
N
is an unbounded set in
(
N
,
d
)
(\mathbb{N}, d)
(
N
,
d
)
. b) Find a metric
d
d
d
on
N
\mathbb{N}
N
such that
N
\mathbb{N}
N
is a bounded set in
(
N
,
d
)
(\mathbb{N}, d)
(
N
,
d
)
. c) Find a metric
d
d
d
on
N
\mathbb{N}
N
such that for every
n
∈
N
n \in \mathbb{N}
n
∈
N
and every
ϵ
>
0
\epsilon > 0
ϵ
>
0
, there exists an
m
∈
N
m \in \mathbb{N}
m
∈
N
such that
d
(
n
,
m
)
<
ϵ
d(n,m) < \epsilon
d
(
n
,
m
)
<
ϵ
.
Related theory
metric-spaces
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