orientation
The concept of orientation looks so magical if we think of various formulations all describe exactly the same … 続きを読む
Mathematics
common cellular structures on a topological space and their properties
Despite the cellular structure on a space is a fundamental ingredients of algebraic topology, this topic seems … 続きを読む
recurrence relation of 2nd-order
The following is a purely computational; including a process of converting a generating function to its formal … 続きを読む
Grothendieck Group
To give a functor from a category of commutative monoid to the category of abelian group, namely,   … 続きを読む
H space (spanier)
Introducing H space along with the Spanier’s text Algebraic Topology. The proof in the article is basica … 続きを読む
モジュライとは何ものか
中学数学でモジュライの概念を説明できるものがあるので、それについて説明したいと思う。 まずモジュライ(空間)というのは, 平易に言うならば「ある性質」を持つ図形をその性質を持つ図形全体の中で「点」として捉えることで、「あ … 続きを読む
local compactness
* Q is not locally compact, since for any positive irrational number ε, I(ε)=[-ε,ε] is not compact in Q. Remem … 続きを読む
holomorphic function germsによるcovering
Riemann Surface と, 有理型関数体上の次既約多項式が与えられたとき, のbranched holomorphic -sheeted coveringとなる新しいRiemann Surface が同型を除い … 続きを読む