25/11/13 20:33:04.45 4Nc81kvo.net
>>861
>日本語版Wikipediaでは、obstructionについて説明したものがないな やれやれ・・・
>それじゃ、代数学の基本定理が、なぜ層で語れるのか、分かりようもない
ほほう、ソウソウ・・ ソウなんかｗ（ソウ＝層）
層と言えば、岡潔
岡潔といえば、多変数解析函数論
多変数解析函数論といえば、御大か
まあ、ここは プロ数学者も巡回しているから
『”層＋obstruction”→ 代数学の基本定理が導けるぞ！』ｗｗｗ
についての 論争を期待しています （＾＾
がんばってくれ！！
逃げないようにｗｗ ；ｐ）
(参考)（関係なさそうだが 検索ヒット："obstruction" sheaf math したの貼る）
”In a 1959 letter to Serre, Grothendieck observed that a fundamental obstruction to constructing good moduli spaces is the existence of automorphisms.”な
URLﾘﾝｸ(en.wikipedia.org)(mathematics)
Stack (mathematics)
In mathematics a stack or 2-sheaf is, roughly speaking, a sheaf that takes values in categories rather than sets. Stacks are used to formalise some of the main constructions of descent theory, and to construct fine moduli stacks when fine moduli spaces do not exist.
Motivation and history
The concept of stacks has its origin in the definition of effective descent data in Grothendieck (1959).
In a 1959 letter to Serre, Grothendieck observed that a fundamental obstruction to constructing good moduli spaces is the existence of automorphisms.
Mumford (1965) studied the Picard group of the moduli stack of elliptic curves, before stacks had been defined.
Stacks were first defined by Giraud (1966, 1971), and the term "stack" was introduced by Deligne & Mumford (1969) for the original French term "champ" meaning "field". In this paper they also introduced Deligne–Mumford stacks, which they called algebraic stacks, though the term "algebraic stack" now usually refers to the more general Artin stacks introduced by Artin (1974).
URLﾘﾝｸ(en.wikipedia.org)
Perfect obstruction theory
In algebraic geometry, given a Deligne–Mumford stack X, a perfect obstruction theory for X consists of:
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