ガロア第一論文と乗数イデアル他関連資料スレ3

[過去ﾛｸﾞ] ガロア第一論文と乗数イデアル他関連資料スレ3 (1002ﾚｽ)
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207: １３２人目の素数さん [] 2023/04/17(月) 13:18:16.77 ID:Pi/h2IHq

>>202
>非可算個の異種R^4の表現法でも示してくれないか？

取りあえず下記でも
なお、「m <= 2n（従って次元は多くとも |符号| の 10/8 倍である）とすると、古田幹雄は滑らかな構造が存在しないことを証明した(Furuta 2001)」にご注目
(20年経って 佐野岳人氏登場>>199)

（参考）
https://ja.wikipedia.org/wiki/4%E6%AC%A1%E5%85%83%E5%A4%9A%E6%A7%98%E4%BD%93
4次元多様体
滑らかな 4次元多様体
・交叉形式が不定値で、偶であると、・・
　m <= 2n（従って次元は多くとも |符号| の 10/8 倍である）とすると、古田幹雄は滑らかな構造が存在しないことを証明した(Furuta 2001)。このことは 10/8 と 11/8 間にギャップがあり、そこでの答えは未解決である。

対照的に、向き付けされた 4次元多様体上の滑らかな構造を分類する第二の問題はほとんど分かっていない。
ドナルドソンは、ドルガチェフ曲面（英語版）のような、単連結でコンパクトな 4次元多様体が存在し、可算無限個の異なる滑らかな構造が存在することを示した。R4 上には非可算無限個の異なる滑らかな構造が存在する。エキゾチック R4を参照。

https://ja.wikipedia.org/wiki/%E3%82%A8%E3%82%AD%E3%82%BE%E3%83%81%E3%83%83%E3%82%AF_R4
エキゾチック R4
https://en.wikipedia.org/wiki/Exotic_R4
Exotic R^4
In mathematics, an exotic
R^4 is a differentiable manifold that is homeomorphic (i.e. shape preserving) but not diffeomorphic (i.e. non smooth) to the Euclidean space R^4.
The first examples were found in 1982 by Michael Freedman and others, by using the contrast between Freedman's theorems about topological 4-manifolds, and Simon Donaldson's theorems about smooth 4-manifolds.[1][2] There is a continuum of non-diffeomorphic differentiable structures of R^4, as was shown first by Clifford Taubes.[3]

つづく

http://rio2016.5ch.net/test/read.cgi/math/1680684665/207

208: １３２人目の素数さん [] 2023/04/17(月) 13:18:45.58 ID:Pi/h2IHq

>>207
つづき

Prior to this construction, non-diffeomorphic smooth structures on spheres ? exotic spheres ? were already known to exist, although the question of the existence of such structures for the particular case of the 4-sphere remained open (and still remains open as of 2023). For any positive integer n other than 4, there are no exotic smooth structures on
R^n; in other words, if n ≠ 4 then any smooth manifold homeomorphic to
R^n is diffeomorphic to R^n.[4]

https://en.wikipedia.org/wiki/Clifford_Taubes
Clifford Henry Taubes (born February 21, 1954)[1] is the William Petschek Professor of Mathematics at Harvard University and works in gauge field theory, differential geometry, and low-dimensional topology. His brother is the journalist Gary Taubes.
Early career
Taubes received his PhD in physics in 1980 under the direction of Arthur Jaffe, having proven results collected in (Jaffe & Taubes 1980) about the existence of solutions to the Landau?Ginzburg vortex equations and the Bogomol'nyi monopole equations.
Soon, he began applying his gauge-theoretic expertise to pure mathematics. His work on the boundary of the moduli space of solutions to the Yang-Mills equations was used by Simon Donaldson in his proof of Donaldson's theorem. He proved in (Taubes 1987) that R4 has an uncountable number of smooth structures (see also exotic R4), and (with Raoul Bott in Bott & Taubes 1989) proved Witten's rigidity theorem on the elliptic genus.
Work based on Seiberg?Witten theory
In a series of four long papers in the 1990s (collected in Taubes 2000), Taubes proved that, on a closed symplectic four-manifold, the (gauge-theoretic) Seiberg?Witten invariant is equal to an invariant which enumerates certain pseudoholomorphic curves and is now known as Taubes's Gromov invariant. This fact improved mathematicians' understanding of the topology of symplectic four-manifolds.
(引用終り)
以上

http://rio2016.5ch.net/test/read.cgi/math/1680684665/208

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