De Rham and infinitesimal cohomology in Kapranov's model for noncommutative algebraic geometry

Effective de Rham Cohomology - The Hypersurface Case

We prove an effective bound for the degrees of generators of the algebraic de Rham cohomology of smooth affine hypersurfaces. In particular, we show that the de Rham cohomology H_dR^p(X) of a smooth hypersurface X of degree d in C^n can be generated by differential forms of degree d^O(pn). This result is relevant for the algorithmic computation of the cohomology, but is also motivated by questions in the theory of ordinary differential equations related to the infinitesimal Hilbert 16th problem.

Motives and algebraic de rham cohomology

In this paper, we define a certain Hodge-theoretic structure for an arbitrary variety X over the complex number field by using the theory of mixed Hodge module due to Morihiko Saito. We call it an arithmetic Hodge structure of X. It is shown that extension groups of arithmetic Hodge structure do not vanish even for degree $\geq2$. Moreover, we define higher Abel-Jacobi maps from Bloch's higher Chow groups of X to these extension groups. These maps essentially involve the classical Abel-Jacobi maps by Weil and Griffiths, and Mumford's infinitesimal invariants of 0-cycles on surfaces.

Effective de Rham Cohomology - The General Case

Grothendieck has proved that each class in the de Rham cohomology of a smooth complex affine variety can be represented by a differential form with polynomial coefficients. After having proved a single exponential bound for the degrees of these forms in the case of a hypersurface, here we generalize this result to arbitrary codimension. More precisely, we show that the p-th de Rham cohomology of a smooth affine variety of dimension m and degree D can be represented by differential forms of degree (pD)^{O(pm)}. This result is relevant for the algorithmic computation of the cohomology, but is al…

Direct image of logarithmic complexes and infinitesimal invariants of cycles

We show that the direct image of the filtered logarithmic de Rham complex is a direct sum of filtered logarithmic complexes with coefficients in variations of Hodge structures, using a generalization of the decomposition theorem of Beilinson, Bernstein and Deligne to the case of filtered $D$-modules. The advantage of using the logarithmic complexes is that we have the strictness of the Hodge filtration by Deligne after taking the cohomology group in the projective case. As a corollary, we get the total infinitesimal invariant of a (higher) cycle in a direct sum of the cohomology of filtered lo…

Periodic cyclic homology as sheaf cohomology

We study a noncommutative version of the infinitesimal site of Grothendieck. A theorem of Grothendieck establishes that the cohomology of the structure sheaf on the infinitesimal topology of a scheme of characteristic zero is de Rham cohomology. We prove that, for the noncommutative infinitesimal topology of an associative algebra over a field of characteristic zero, the cohomology of the structure sheaf modulo commutators is periodic cyclic cohomology. We also compute the noncommutative infinitesimal cohomology of other sheaves. For example we show that hypercohomology with coefficients in $K…

刚性解析空间的晶体上同调

Crystalline cohomology of rigid analytic spaces

本文针对未必光滑的刚性解析空间，引入系数在p进域或Fontaine的de Rham周期环中的无穷小上同调，推广了晶体上同调理论。

The de Rham realization of the elliptic polylogarithm in families

This thesis establishes a geometric approach to the de Rham realization of the polylogarithm. As a central result we construct the logarithm sheaves of rational abelian schemes in terms of the birigidified Poincaré bundle with universal integrable connection on the product of the abelian scheme and the universal vectorial extension of its dual. This is achieved essentially by restricting the mentioned data of the Poincaré bundle along the infinitesimal neighborhoods of the zero section of the universal extension. We also clarify how these constructions naturally express within the language of …

特征 $p>2$ 下导出概型的 $(-1)$-平移达布定理

$(-1)$-Shifted Darboux theorem of derived schemes in characteristic $p>2$

本文针对特征$p>2$的情形，证明了带无穷小结构的$(-1)$-平移辛形式的达布定理，利用Antieau的导出无穷小上同调给出特征无关论证，并推广相关存在性定理，为导出几何中的唐纳森-托马斯理论提供支撑。

Characteristic 0 and p analogies, and some motivic cohomology

The purpose of this survey is to explain some recent results about analogies between characteristic 0 and characteristic $p>0$ geometry, and to discuss an infinitesimal variant of motivic cohomology. More specifically, we review results showing that the big de Rham Witt complex of a field is a complex of 0-cycles (section 2), as well as results showing analogies between char. $p>0$ and char. 0 geometry. Some of those results determine local cohomology invariants of singular varieties (section 3) and others are concerned with congruences modulo $q$-powers for the number of rational points of va…

环面幺半群概形的 Hall 李代数

Hall Lie algebras of toric monoid schemes

本文为射影环面簇构造 Hall 李代数，证明其包络代数结构，并在若干例子中与已知李代数建立联系。