개집합

// from wpen
실직선,real_line 위의 열린구간,open_interval을 일반화,generalization한 개념임.

// from mw
2차원에선 open set은 원판,disk,
3차원에선 open set은 공,ball.
open set의 complement(set_complement)은 닫힌집합,closed_set.

opp. 닫힌집합,closed_set

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

Twins:
Open_set
열린집합
Open_set
https://mathworld.wolfram.com/OpenSet.html

Up: 집합,set
열림,openness

열린집합 닫힌집합
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 { 극한점 limit_point https://mathworld.wolfram.com/LimitPoint.html 수학백과: 극한점
https://encyclopediaofmath.org/wiki/Limit_point_of_a_set
극한점 극한점 limit_point 극한점}
집적점? accumulation_point accumulation_point =,accumulation_point . accumulation_point {
accumulation_point = https://en.wiktionary.org/wiki/accumulation_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 complete_accumulation_point https://encyclopediaofmath.org/wiki/Complete_accumulation_point Up: 완비성,completeness? }

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

위상,topology - 위상,topology
위상수학,topology
위상공간,topological_space - 위상공간,topological_space

... open closed set
}