tree Van Emde Boas tree(英语:Van Emde Boas tree) Rose tree(英语:Rose tree) 四叉树 線段樹 Intervaltree(英语:Intervaltree) Range tree(英语:Range tree) Bin(英语:Bin) K-d树
the real line is ℵ 1 {\displaystyle \aleph _{1}} -dense if every open interval contains ℵ 1 {\displaystyle \aleph _{1}} -many elements of X. Whether all