1 A nice book is Völklein's "Groups as Galois Groups", where this is discussed in a fairly elementary manner. The relevant paper by Thompson: Some finite groups which appear as GalL/K , where K⊆Q(µn) . J. Algebra 89, 437--499, dx.doi.org/10.1016/0021-8693(84)90228-X . – Steve D CommentedFeb 12, 2010 at 16:46
3 M23 has now been achieved as well. – Akiva Weinberger Commented Aug 11 2026at 14:56 @AkivaWeinberger, wow! From last month! math.mit.edu/~poonen/papers/M23.pdf – none Commented6 hours ago
2 Answers 92 the monster is a nice example of how the so-called rigidity method for the inverse Galois problem works. There is a lot of beautiful mathematics behind this, I will sketch the different steps. 略 answered Feb 2, 2010 at 19:56 Wanderer's user avatar Wanderer 略
私には ありがたいお経ですが(^^ (google検索) invariance of plurigenera Multiplier ideal sheaf <AI による概要> invariance of plurigenera refers to the theorem proving that the plurigenera \(\dim_\mathbb{C} \Gamma(X_t, mK_{X_t})\) of the fibers \(X_{t}\) in a smooth projective (or Kähler) family π: X → Δ of varieties of general type are independent of t ∈ Δ for any positive integer m. http://ui.adsabs.harvard.edu/abs/1998InMat.134..661S/abstract Invariance of plurigenera Siu, Yum-Tong The following conjecture on the deformation invariance of plurigenera is proved. For a smooth projective holomorphic family of compact complex manifolds over the open unit 1-disk such that all the fibers are of general type, every plurigenus of the fiber is independent of the fiber. The proof uses Nadel's multiplier ideal sheaves, Skoda's result on the generation of ideals with L2 estimates with respect to a plurisubharmonic weight, and the extension theorem of Ohsawa-Takegoshi-Manivel for holomorphic top-degree forms which are L2 with respect to a plurisubharmonic weight. Publication: Inventiones Mathematicae, vol. 134, issue 3, pp. 661-673 Pub Date: November 1998 Core Role of Multiplier Ideal Sheaves In Siu's proof and subsequent analytic/algebraic developments, multiplier ideal sheaves (such as Nadel's multiplier ideal sheaves) play a critical foundational role: http://arxiv.org/abs/alg-geom/9712016 [Submitted on 15 Dec 1997] Invariance of Plurigenera Yum-Tong Siu (Harvard University) The following conjecture on the deformation invariance of plurigenera is proved. For a smooth projective holomorphic family of compact complex manifolds over the open unit 1-disk such that all the fibers are of general type, every plurigenus of the fiber is independent of the fiber. The proof uses Nadel's multiplier ideal sheaves, Skoda's result on the generation of ideals with L2 estimates with respect to a plurisubharmonic weight, and the extension theorem of Ohsawa-Takegoshi-Manivel for holomorphic top-degree forms which are L2 with respect to a plurisubharmonic weight.
・L² Extension Techniques: The proof relies heavily on the Ohsawa-Takegoshi-Manivel L² extension theorem for holomorphic top-degree forms with respect to plurisubharmonic weights. http://arxiv.org/pdf/alg-geom/9712016 Invariance of Plurigenera Yum-Tong Siu 1 September 1997
・ Multiplier ideal sheaves measure the singularities of plurisubharmonic weights and metrics on the canonical bundle or line bundles. They ensure that local L² estimates can be controlled and glued globally across the family. http://arxiv.org/html/0803.2454v1 17 Mar 2008 Finite Generation of Canonical Ring by Analytic Method Dedicated to Professor Lu Qikeng on his 80th Birthday Yum-Tong Siu 1 By analyzing the vanishing or triviality of multiplier ideal sheaves along central fibers, sections of pluricanonical bundles on a fiber \(X_{t}\) can be extended to the entire family X, showing that the dimension of the space of sections cannot jump and remains constant.
Would you like to explore a specific aspect of this topic, such as: • The precise role of the Ohsawa-Takegoshi extension theorem? • How Nadel's multiplier ideal sheaves are defined in this setting? • Extensions of this theorem to Kähler families or generalized polarized pairs? (引用終り) 以上
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http://en.wikipedia.org/wiki/K%C3%A4hler%E2%80%93Einstein_metric Kähler–Einstein metric 略 When first Chern class is not definite, or we have intermediate Kodaira dimension, then finding canonical metric remained as an open problem, which is called the algebrization conjecture via analytical minimal model program. Definition Einstein manifolds Main article: Einstein manifold 略 http://en.wikipedia.org/wiki/Einstein_manifold Einstein manifold 微分幾何学と数理物理学において、アインシュタイン多様体は、リッチテンソルが計量に比例するリーマン多様体または擬リーマン微分 可能多様体である。この条件は計量が真空アインシュタイン場方程式(宇宙定数)の解であることと同等であるため、アインシュタイン多様体はアルバート・アインシュタインにちなんで名付けられている。ただし、計量の次元と符号はどちらも任意であり、したがってローレンツ多様体(一般相対性理論で通常研究される4次元ローレンツ多様体を含む)に限定されない。4次元ユークリッド空間のアインシュタイン多様体は、重力インスタントンとして研究されている。 略 アプリケーション 4 次元リーマン アインシュタイン多様体は、量子重力理論における重力インスタントンとして、数理物理学においても重要である。 「重力インスタントン」という用語は、ワイル テンソルが反自己双対であるアインシュタイン 4 多様体に限定される場合があり、計量は有限商ユークリッド 4 空間上の標準計量に漸近的であると仮定されることが多い (したがって、完備であるが非コンパクトである)。 微分幾何学では、単連結自己双対アインシュタイン 4 多様体は、リッチ平坦の場合には 4 次元逆向きハイパーケーラー多様体と一致するが、それ以外の場合には、四元数ケーラー多様体と呼ばれることがある。