Database
BASIC TOPOLOGY
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Limit points and perfect sets
perflp
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perfi
Metamath Proof Explorer
Ascii
Unicode
Theorem
perflp
Description:
The limit points of a perfect space.
(Contributed by
Mario Carneiro
, 24-Dec-2016)
Ref
Expression
Hypothesis
lpfval.1
⊢
X
=
⋃
J
Assertion
perflp
⊢
J
∈
Perf
→
limPt
⁡
J
⁡
X
=
X
Proof
Step
Hyp
Ref
Expression
1
lpfval.1
⊢
X
=
⋃
J
2
1
isperf
⊢
J
∈
Perf
↔
J
∈
Top
∧
limPt
⁡
J
⁡
X
=
X
3
2
simprbi
⊢
J
∈
Perf
→
limPt
⁡
J
⁡
X
=
X