We define a new type of Hall algebras associated e.g. with quivers with polynomial potentials. The main difference with the conventional definition is that we use cohomology of the stack of representations instead of constructible sheaves or functions. In order to take into account the potential we introduce a generalization of theory of mixed Hodge structures, related to exponential integrals. Generating series of our Cohomological Hall algebra is a generalization of the motivic Donaldson-Thomas invariants introduced in arXiv:0811.2435. Also we prove a new integrality property of motivic Donaldson-Thomas invariants.

https://www.intlpress.com/site/pub/files/_fulltext/journals/cntp/2011/0005/0002/CNTP-2011-0005-0002-a001.pdf

Cohomological Hall algebra, exponential Hodge structures and motivic Donaldson-Thomas invariants

The main result of this paper is the existence of Galois representations associated with the mod p (or mod p m ) cohomology of the locally symmetric spaces for GLn over a totally real or CM eld, proving conjectures of Ash and others. Following an old suggestion of Clozel, recently realized by Harris-Lan-Taylor-Thorne for characteristic 0 cohomology classes, one realizes the cohomology of the locally symmetric spaces for GLn as a boundary contribution of the cohomology of symplectic or unitary Shimura varieties, so that the key problem is to understand torsion in the cohomology of Shimura varieties. Thus, we prove new results on the p-adic geometry of Shimura varieties (of Hodge type). Namely, the Shimura varieties become perfectoid when passing to the inverse limit over all levels at p, and a new period map towards the ag variety exists on them, called the Hodge-Tate period map. It is roughly analogous to the embedding of the hermitian symmetric domain (which is roughly the inverse limit over all levels of the complex points of the Shimura variety) into its compact dual. The Hodge-Tate period map has several favorable properties, the most important being that it commutes with the Hecke operators away from p (for the trivial action of these Hecke operators on the ag variety), and that automorphic vector bundles come via pullback from the ag variety.

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On torsion in the cohomology of locally symmetric varieties

V.G. Berkovich’s non-Archimedean analytic geometry provides a natural framework to understand the combinatorial aspects in the theory of toric varieties and toroidal embeddings. This point of view leads to a conceptual and elementary proof of the following results: if X is an algebraic scheme over a perfect field and if D is the exceptional normal crossing divisor of a resolution of the singularities of X, the homotopy type of the incidence complex of D is an invariant of X. This is a generalization of a theorem due to D. Stepanov.

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Géométrie toroïdale et géométrie analytique non archimédienne. Application au type d’homotopie de certains schémas formels

We describe a new approach to relative p-adic Hodge theory based on systematic use of Witt vector constructions and nonarchimedean analytic geometry in the style of both Berkovich and Huber. We give a thorough development of phi-modules over a relative Robba ring associated to a perfect Banach ring of characteristic p, including the relationship between these objects and etale Z_p-local systems and Q_p-local systems on the algebraic and analytic spaces associated to the base ring, and the relationship between etale cohomology and phi-cohomology. We also make a critical link to mixed characteristic by exhibiting an equivalence of tensor categories between the finite etale algebras over an arbitrary perfect Banach algebra over a nontrivially normed complete field of characteristic p and the finite etale algebras over a corresponding Banach Q_p-algebra. This recovers the homeomorphism between the absolute Galois groups of F_p((pi)) and Q_p(mu_{p^infty}) given by the field of norms construction of Fontaine and Wintenberger, as well as generalizations considered by Andreatta, Brinon, Faltings, Gabber, Ramero, Scholl, and most recently Scholze. Using Huber's formalism of adic spaces and Scholze's formalism of perfectoid spaces, we globalize the constructions to give several descriptions of the etale local systems on analytic spaces over p-adic fields. One of these descriptions uses a relative version of the Fargues-Fontaine curve.

Relative P-adic Hodge Theory: Foundations

Global analysis describes diverse yet interrelated research areas in analysis and algebraic geometry, particularly those in which Kunihiko Kodaira made his most outstanding contributions to mathematics. The eminent contributors to this volume, from Japan, the United States, and Europe, have prepared original research papers that illustrate the progress and direction of current research in complex variables and algebraic and differential geometry. The authors investigate, among other topics, complex manifolds, vector bundles, curved 4-dimensional space, and holomorphic mappings. Bibliographies facilitate further reading in the development of the various studies.Originally published in 1970.The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

Global Analysis: Papers in Honor of K. Kodaira (Pms-29)

http://www.math.huji.ac.il/~temkin/lectures/Hironaka80.pdf

Desingularization of quasi-excellent schemes in characteristic zero

On local properties of non-Archimedean analytic spaces

http://www.math.huji.ac.il/~temkin/lectures/Inseparable_Local_Uniformization_Lecture.pdf

Inseparable local uniformization

The non-Archimedean analytic spaces are studied. We extend to the general case notions and results defined earlier only for strictly analytic spaces. In particular, we prove that any strictly analytic space admits a unique rigid model.

/pdf/on-local-properties-of-non-archimedean-analytic-spaces-ii-5egd8mllsf.pdf

On local properties of non-Archimedean analytic spaces II

We generalize theorems of Deligne-Mumford and de Jong on semi-stable modifications of families of proper curves. The main result states that after a generically \'etale alteration of the base any (not necessarily proper) family of multipointed curves with semi-stable generic fiber admits a minimal semi-stable modification. The latter can also be characterized by the property that its geometric fibers have no certain exceptional components. The main step of our proof is uniformization of one-dimensional extensions of valued fields. Riemann-Zariski spaces are then used to obtain the result over any integral base.

Michael Temkin

Papers

Desingularization of quasi-excellent schemes in characteristic zero

On local properties of non-Archimedean analytic spaces

Inseparable local uniformization

On local properties of non-Archimedean analytic spaces II

Stable modification of relative curves