'''열린집합, 개집합, open set'''

// from wpen
[[실직선,real_line]] 위의 [[열린구간,open_interval]]을 [[일반화,generalization]]한 개념임.

// from mw
2차원에선 open set은 [[원판,disk]],
3차원에선 open set은 [[공,ball]].
'''open set'''의 [[complement]](set_complement)은 [[닫힌집합,closed_set]].

opp. [[닫힌집합,closed_set]]

MKLINK
[[거리공간,metric_space]]
[[근방,neighborhood]]
[[반지름,radius]]
[[중심,center]]

----
Twins:

[[WpSp:Open_set]]
= https://simple.wikipedia.org/wiki/Open_set

WpKo:열린집합
= https://ko.wikipedia.org/wiki/열린집합

WpEn:Open_set
= https://en.wikipedia.org/wiki/Open_set

MathWorld:OpenSet
= https://mathworld.wolfram.com/OpenSet.html

https://encyclopediaofmath.org/wiki/Open_set - ''in a topological space'' // [[위상공간,topological_space]]

https://librewiki.net/wiki/열린_집합

Ggl:"definition of open set"

Up: [[집합,set]]
[[열림,openness]]? or [[열림성,openness]]

----
Ggl:열린집합+닫힌집합
Naver:열린집합+닫힌집합
----
ALSOIN [[닫힌집합,closed_set]] ... 그럼 [[열린집합과_닫힌집합,open_and_closed_set]] 을 만들?
{
http://mathonline.wikidot.com/the-open-and-closed-sets-of-a-topological-space

MKLINK
극한점? [[limit_point]] [[극한점,limit_point]] =극한점, =,limit_point . limit_point {
'''limit point'''
'''극한점'''

WtEn:limit_point = https://en.wiktionary.org/wiki/limit_point#English
https://mathworld.wolfram.com/LimitPoint.html [[https://terms.naver.com/entry.naver?docId=3404989&cid=47324&categoryId=47324 수학백과: 극한점]]
https://encyclopediaofmath.org/wiki/Limit_point_of_a_set
WpEn:Limit_point redir to WpEn:Accumulation_point
Ndict:극한점 Ggl:극한점 Srch:limit_point Srch:극한점}

[[accumulation_point]] Srch:accumulation_point =,accumulation_point . accumulation_point {
'''accumulation point'''
'''집적점'''

WtEn:accumulation_point = https://en.wiktionary.org/wiki/accumulation_point
 위상 해석 모두에서 cluster_point limit_point 와 동의어라 함
WtEn:limit_point = https://en.wiktionary.org/wiki/limit_point#English
 에서는 "(point whose every neighborhood contains a point in a given subset):"

https://en.wikipedia.org/wiki/Accumulation_point
 (Redirected from WpEn:Limit_point )

https://mathworld.wolfram.com/AccumulationPoint.html
https://encyclopediaofmath.org/wiki/Accumulation_point

Sub: [[complete_accumulation_point]] =,complete_accumulation_point . complete_accumulation_point { '''complete accumulation point''' WtEn:complete_accumulation_point https://encyclopediaofmath.org/wiki/Complete_accumulation_point Up: [[완비성,completeness]]? }

Srch:집적점 Ndict:집적점 Ggl:집적점 Srch:accumulation_point Srch:집적점 } // 위상에서 이 둘은 동의어? chk
clopen_set [[clopen_set]] =,clopen_set . clopen_set { [[닫힌집합,closed_set]] ... WtEn:clopen_set https://en.citizendium.org/wiki/Clopen_set (한줄 short)
https://proofwiki.org/wiki/Definition:Clopen_Set
WpEn:Clopen_set
https://encyclopediaofmath.org/wiki/Open-closed_set
Google:clopen+set
}

[[위상,topology]] - [[VG:위상,topology]]
[[위상수학,topology]]
[[위상공간,topological_space]] - [[VG:위상공간,topological_space]]

... Google:open+closed+set
}