A pamphlet on motivic cohomology

Arakelov motivic cohomology II

We show that the constructions done in part I generalize their classical counterparts: firstly, the classical Beilinson regulator is induced by the abstract Chern class map from $BGL$ to the Deligne cohomology spectrum. Secondly, Arakelov motivic cohomology is a generalization of arithmetic $K$-theory and arithmetic Chow groups. Finally, we give a conceptual explanation of the height pairing: it is given by the natural pairing of motivic homology and Arakelov motivic cohomology.

示性形式用于动机上同调

Trace formalism for motivic cohomology

本文旨在构建Voevodsky、Ayoub和Cisinski-Déglise提出的动机上同调六 functor 形式中的跟踪映射，并构建其∞增强形式。通过使用Suslin-Voevodsky的相对循环群以更 functorial 的方式重新解释跟踪形式。

Motivic cohomology of the complement of hyperplane arrangements

We give a presentation of the motivic cohomology ring of the complement of a hyperplane arrangement considered as algebra over the motivic cohomology of the ground field.

Duality for integral motivic cohomology

We discuss duality pairings on integral étale motivic cohomology groups of regular and proper schemes over algebraically closed fields, local fields, finite fields, and arithmetic schemes.

关于动机上同调的弗罗贝尼乌斯刚性

On Frobenius rigidity for motivic cohomology

该研究探讨光滑真代数簇的两类上同调在基域扩张下的性质，证明有限系数下弗罗贝尼乌斯纤维与基域无关，补充了特征处动机上同调的相关结论。

Functional equations of the dilogarithm in motivic cohomology

We prove relations between fractional linear cycles in Bloch's integral cubical higher Chow complex in codimension two of number fields, which correspond to functional equations of the dilogarithm. These relations suffice, as we shall demonstrate with a few examples, to write down enough relations in Bloch's integral higher Chow group CH^2(F,3) for certain number fields F to detect torsion cycles. Using the regulator map to Deligne cohomology, one can check the non-triviality of the torsion cycles thus obtained. Using this combination of methods, we obtain explicit higher Chow cycles generatin…

General Motivic Cohomology and Symplectic Orientation

In this paper, we present a general approach to establish motivic cohomology and build part of its six operations formalism. Applying this together with symplectic orientation on MW-motivic cohomology, we discuss the embedding theorem of effective Chow-Witt motives.

On motivic cohomology with Z/l coefficients

In this paper we give a proof of the Bloch-Kato conjecture relating motivic cohomology and etale cohomology. It is a corrected version of the paper with the same title which posted earlier.

Reduced power operations in motivic cohomology

In this paper we construct an analog of Steenrod operations in motivic cohomology and prove their basic properties including the Cartan formula, the Adem relations and the realtions to characteristic classes.

Karoubi's Construction for Motivic Cohomology Operations

We use an analogue of Karoubi's construction in the motivic situation to give some cohomology operations in motivic cohomology. We prove many properties of these operations, and we show that they coincide, up to some nonzero constants, with the reduced power operations in motivic cohomology originally constructed by Voevodsky. The relation of our construction to Voevodsky's is, roughly speaking, that of a fixed point set to its associated homotopy fixed point set.

混合特征概形的动机上同调

Motivic cohomology of mixed characteristic schemes

本文为拟紧拟分离概形引入一种动机上同调理论，推广了Elmanto--Morrow的构造，利用拓扑循环同调上的整体滤过提供导出de Rham与合成上同调的整数细化，并满足与étale上同调及非连通代数$K$-理论的关系。

混合特征母题上同调的Weibel消没与射影丛公式

Weibel vanishing and the projective bundle formula for mixed characteristic motivic cohomology

本文证明混合特征概形的母题上同调满足Weibel消没的母题精细化、射影丛公式等预期性质，并将其与Milnor K理论比较，从而把Elmanto–Morrow的结果推广到非域上概形。

On a motivic interpretation of primitive, variable and fixed cohomology

This note addresses the motivic nature of some classical cohomological results due to Lefschetz, namely the primitive decomposition (for the cohomology of smooth projective varieties), and, secondly, the splitting of the cohomology of a complete intersection into the "fixed" and "variable part".

动机上同调的贝林森 - 利希滕鲍姆现象

Beilinson--Lichtenbaum phenomenon for motivic cohomology

研究非\(\mathbb{A}^1\)不变动机上同调，通过证明\(p\)进动机上同调到巴特 - 卢里合系上同调的圈类映射是同构，验证猜想，还证明了能恢复经典定义及给出纯度定理，关键是加伯表示引理的混合特征非诺特版本。

Arakelov motivic cohomology I

This paper introduces a new cohomology theory for schemes of finite type over an arithmetic ring. The main motivation for this Arakelov-theoretic version of motivic cohomology is the conjecture on special values of $L$-functions and zeta functions formulated by the second author. Taking advantage of the six functors formalism in motivic stable homotopy theory, we establish a number of formal properties, including pullbacks for arbitrary morphisms, pushforwards for projective morphisms between regular schemes, localization sequences, $h$-descent. We round off the picture with a purity result an…

关于A-动机上同调的整数部分

On the Integral Part of A-Motivic Cohomology

本文研究了正特征全局域上的A-动机上同调的整数部分，提出模型版本和l-adic版本的定义，并证明模型版本包含l-adic版本，同时探讨了regulated extensions的子模块。

On 2-torsion in motivic cohomology

In this paper we prove the 2-local part of the Beilinson-Lichtenbaum conjectures on tosion in motivic cohomology. In particular we prove the Milnor conjecture relating Milnor's K-theory and the Galois cohomology with Z/2-coefficients. This paper is a new version of the previously distributed preprint "The Milnor Conjecture".

Motivic action for Siegel modular forms

We study the coherent cohomology of automorphic sheaves corresponding to Siegel modular forms $f$ of low weight on ${\rm GSp}(4)$ Shimura varieties. Inspired by the work of Prasanna--Venkatesh on singular cohomology of locally symmetric spaces, we propose a conjecture that explains all the contributions of a Hecke eigensystem to coherent cohomology in terms of the action of a motivic cohomology group. Under some technical conditions, we prove that our conjecture is equivalent to Beilinson's conjecture for the adjoint $L$-function of $f$. We also prove some unconditional results in special case…

超平面排列补集的Milnor-Witt动机上同调

Milnor-Witt motivic cohomology of complements of hyperplane arrangements

本文计算仿射空间中超平面排列补集的Milnor-Witt动机上同调，给出其代数结构，并通过实现到经典上同调获得推论。

Parshin's conjecture and motivic cohomology with compact support

We discuss Parshin's conjecture on rational K-theory over finite fields and its implications for motivic cohomology with compact support.

Towards motivic quantum cohomology of $\bar{M}_{0,S}$

We explicitly calculate some Gromov--Witten correspondences determined by maps of labeled curves of genus zero to the moduli spaces of labeled curves of genus zero. We consider these calculations as the first step towards studying the self--referential nature of motivic quantum cohomology.

From algebraic cobordism to motivic cohomology

Let S be an essentially smooth scheme over a field of characteristic exponent c. Let MGL and HZ denote the algebraic cobordism spectrum and the motivic cohomology spectrum over S, respectively. We show that the canonical map MGL/(a1, a2, ...) -> HZ induced by the additive orientation of motivic cohomology becomes an equivalence after inverting c. As an application, we prove the convergence of the Atiyah-Hirzebruch spectral sequence for all Z[1/c]-local Landweber exact motivic spectra.

Motivic cohomology and infinitesimal group schemes

For $k$ a perfect field of characteristic $p>0$ and $G/k$ a split reductive group with $p$ a non-torsion prime for $G,$ we compute the mod $p$ motivic cohomology of the geometric classifying space $BG_{(r)}$, where $G_{(r)}$ is the $r$th Frobenius kernel of $G.$ Our main tool is a motivic version of the Eilenberg-Moore spectral sequence, due to Krishna. For a flat affine group scheme $G/k$ of finite type, we define a cycle class map from the mod $p$ motivic cohomology of the classifying space $BG$ to the mod $p$ étale motivic cohomology of the classifying stack $\mathcal{B}G.$ This also gives …

Motivic classes of classifying stacks of finite groups and unramified cohomology

Combining work of Peyre, Colliot-Thélène and Voisin, we give the first example of a finite group $G$ such that the motivic class of its classifying stack $BG$ in Ekedahl's Grothendieck ring of stacks over $\mathbb{C}$ is non-trivial and $BG$ has trivial unramified Brauer group.

Lectures on motivic cohomology 2000/2001 (written by Pierre Deligne)

These lecture notes cover four topics. There is a proof of the fact that the functors represented by the motivic Eilenberg-Maclane spaces on the motivic homotopy category coincide with the motivic cohomology defined in terms of the motivic complexes. There is a description of the equivariant motivic homotopy category for a finite flat group scheme (over a noetherian base) together with a new characterization of A^1-equivalences. There is a part where we introduce a class of sheaves called solid sheaves. Finally there is a part where we study functors of the form X -> X/G and X -> X^W and show …

About Bredon motivic cohomology of a field

We prove that, over a perfect field, Bredon motivic cohomology can be computed by Suslin-Friedlander complexes of equivariant equidimensional cycles. Partly based on this result we completely identify Bredon motivic cohomology of a quadratically closed field and of a euclidian field in weights 1 and $σ$. We also prove that Bredon motivic cohomology of an arbitrary field in weight 0 with integer coefficients coincides (as abstract groups) with Bredon cohomology of a point.

Carlitz twists: their motivic cohomology, regulators, zeta values and polylogarithms

The integral $t$-motivic cohomology and the class module of a (rigid analytically trivial) Anderson $t$-motive were introduced by the first author in [Gaz22b]. This paper is devoted to their determination in the particular case of tensor powers of the Carlitz $t$-motive, namely, the function field counterpart $\underline{A}(n)$ of Tate twists $\mathbb{Z}(n)$. We find out that these modules are in relation with fundamental objects of function field arithmetic: integral $t$-motivic cohomology governs linear relations among Carlitz polylogarithms, its torsion is expressed in terms of the denomina…

The realization of the degree zero part of the motivic polylogarithm on abelian schemes in Deligne-Beilinson cohomology

We use Burgos theory of arithmetic Chow groups to exhibit a realization of the degree zero part of the polylogarithm on abelian schemes in Deligne-Beilinson cohomology.

The Gm-equivariant Motivic Cohomology of Stiefel Varieties

We derive a version of the Rothenberg-Steenrod, fiber-to-base, spectral sequence for cohomology theories represented in model categories of simplicial presheaves. We then apply this spectral sequence to calculate the equivariant motivic cohomology of the general linear group with a general Gm-action, this coincides with the equivariant higher Chow groups. Some of the equivariant motivic cohomology of a Stiefel variety with a general Gm-action is deduced as a corollary.

Motivic p-adic tame上同调

Motivic p-adic tame cohomology

本文构造了正特征域上tame motives与log-étale motives间的比较函子，推广了已有拓扑比较，并构建了表示模$p^m$ tame motivic cohomology的$E_\infty$-环谱，证明了相关猜想。

Milnor-Witt 动机上同调与线性代数群

Milnor-Witt motivic cohomology and linear algebraic groups

本文计算了辛群及一般线性群等线性代数群的 Milnor-Witt 动机上同调，并确定了其乘法结构。

Topological comparison theorems for Bredon motivic cohomology

We prove equivariant versions of the Beilinson-Lichtenbaum conjecture for Bredon motivic cohomology of smooth complex and real varieties with an action of the group of order two. This identifies equivariant motivic and topological invariants in a large range of degrees.

Geometry of nondegenerate polynomials: Motivic nearby cycles and Cohomology of contact loci

We study polynomials with complex coefficients which are nondegenerate in two senses, one of Kouchnirenko and the other with respect to its Newton polyhedron, through data on contact loci and motivic nearby cycles. Introducing an explicit description of these quantities we can answer in part to questions concerning the motivic nearby cycles of restriction functions and the integral identity conjecture in the context of Newton nondegenerate polynomials. Furthermore, in the nondegeneracy in the sense of Kouchnirenko, we give calculations on cohomology groups of the contact loci.

扭曲射流、母题测度与轨形上同调

Twisted jets, motivic measure and orbifold cohomology

本文通过引入Deligne-Mumford栈上的扭曲射流并研究其母题测度，证明了具有Gorenstein商奇点的双有理极小模型具有相同的带霍奇结构的轨形上同调。

On the push-forwards for motivic cohomology theories with invertible stable Hopf element

We present a geometric construction of push-forward maps along projective morphisms for cohomology theories representable in the stable motivic homotopy category assuming that the element corresponding to the stable Hopf map is inverted in the coefficient ring of the theory. The construction is parallel to the one given by A. Nenashev for derived Witt groups. Along the way we introduce cohomology groups twisted by a formal difference of vector bundles as cohomology groups of a certain Thom space and compute twisted cohomology groups of projective spaces.

Weil上同调理论及其动机Hopf代数胚

Weil cohomology theories and their motivic Hopf algebroids

本文研究代数几何与刚性解析几何中一般Weil上同调理论，用动机理论给出三种等价视角，构造推广的动机Hopf代数胚，并证明经典Weil上同调对应的动机Hopf代数胚的连通性。

Quaternionic Projective Bundle Theorem and Gysin Triangle in MW-Motivic Cohomology

In this paper, we show that the motive of the quaternionic Grassmannian $HP^n$ (as defined by I. Panin and C. Walter) splits in the category of effective MW-motives (as defined by B. Calmès, F. Déglise and J. Fasel). Moreover, we extend this result to an arbitrary symplectic bundle, obtaining the so-called quaternionic projective bundle theorem. Finally, we give the Gysin triangle in MW-motivic cohomology.

Parameterization of factorizable line bundles by K-theory and motivic cohomology

This note corrects a certain construction in (the old version of) the paper [GL]. The construction in question starts from a Brylinski-Deligne datum, which is an extension of a group G by K_2, and produces a factorization line bundle on the affine Grassmannian of the group G.

A comparison theorem for MW-motivic cohomology

We prove that for a finitely generated field over an infinite perfect field k, and for any integer n, the (n,n)-th MW-motivic cohomology group identifies with the n-th Milnor-Witt K-theory group of that field

复数的Bredon母题上同调

Bredon motivic cohomology of the complex numbers

本文在复数域上计算了$C_2$-等变Bredon母题上同调环，并利用刚性将Suslin的经典结果推广到等变母题框架。

Motivic strict ring spectra representing semi-topological cohomology theories

We show that Shipley's "detection functor" for symmetric spectra generalizes to motivic symmetric spectra. As an application, we construct motivic strict ring spectra representing morphic cohomology, semi-topological $K$-theory, and semi-topological cobordism for complex varieties. As a further application to semi-topological cobordism, we show that it is related to semi-topological $K$-theory via a Conner-Floyd type isomorphism and that after inverting a lift of the Friedlander-Mazur $s$-element in morphic cohomology, semi-topological cobordism becomes isomorphic to periodic complex cobordism…

相对德拉姆上同调有限性的一个 motive 证明

A motivic proof of the finiteness of relative de Rham cohomology

该研究针对Q上概形间光滑真态射X/S的相对德拉姆上同调群性质，用A1同伦理论替代霍奇理论与超越方法，快速证明其为基上向量丛。

Oriented Cohomology and Motivic Decompositions of Relative Cellular Spaces

For an oriented cohomology theory A and a relative cellular space X, we decompose the A-motive of X into a direct sum of twisted motives of the base spaces. We also obtain respective decompositions of the A-cohomology of X. Applying them, one can compute A(X), where X is an isotropic projective homogeneous variety and A means algebraic K-theory, motivic cohomology or algebraic cobordism MGL.

Divisibility properties of motivic cohomology

We extend results of Colliot-Thélène and Raskind on the $\mathcal{K}_2$-cohomology of smooth projective varieties over a separably closed field $k$ to the étale motivic cohomology of smooth, not necessarily projective, varieties over $k$. Some consequences are drawn, such as the degeneration of the Bloch-Lichtenbaum spectral sequence for any field containing $k$.

Equivariant cycles and cancellation for motivic cohomology

We introduce a Bredon motivic cohomology theory for smooth schemes defined over a field and equipped with an action by a finite group. These cohomology groups are defined for finite dimensional representations as the hypercohomology of complexes of equivariant correspondences in the equivariant Nisnevich topology. We generalize the theory of presheaves with transfers to the equivariant setting and prove a Cancellation Theorem.

一个motivic积分$p$-adic上同调

A motivic integral $p$-adic cohomology

本文构造了一个积分$p$-adic上同调，与刚性上同调相容，并在奇点消解条件下证明其与Ertl-Shiho-Sprang的“好”上同调一致，从而得到motivic性质和Künneth公式。

The motivic structures $\mathsf{LS}_{12}$ and $\mathsf{S}_{16}$ in the cohomology of moduli spaces of curves

We study the appearances of $\mathsf{LS}_{12}$ and $\mathsf{S}_{16}$ in the weight-graded compactly supported cohomology of moduli spaces of curves. As applications, we prove new nonvanishing results for the middle cohomology groups of $\mathcal{M}_9$ and $\mathcal{M}_{11}$ and give evidence to support the conjecture that the dimension fo $H^{2g + k}_c(\mathcal{M}_g)$ grows at least exponentially with $g$ for almost all $k$.

动机构上同调的Serre型谱序列

A Serre-type spectral sequence for motivic cohomology

本文构造了动机构上同调的Serre型谱序列，并将其应用于射影一般线性群Nisnevich分类空间的动机构上同调计算，从而给出Severi-Brauer簇动机的显式描述。

实数域的 Bredon 动机上同调

Bredon motivic cohomology of the real numbers

本文在实数域上以 $\Z/2$-系数计算 $C_2$-等变 Borel 动机上同调环与 Bredon 动机上同调群，证明其为点空间 $RO(C_2\times C_2)$-分次 Bredon 上同调环的真子环，并推广至任意实闭域。

概形的$\mathbb{A}^1$-不变动机上同调

$\mathbb{A}^1$-invariant motivic cohomology of schemes

本文在任意拟紧拟分离概形上实现了Voevodsky的$\mathbb{A}^1$-不变动机上同调纲领，引入了通过Atiyah--Hirzebruch谱序列与同伦$K$-理论关联的理论，并证明了切片相关猜想。

Kato conjecture and motivic cohomology over finite fields

For an arithmetical scheme X, K. Kato introduced a certain complex of Gersten-Bloch-Ogus type whose component in degree a involves Galois cohomology groups of the residue fields of all the points of X of dimension a. He stated a conjecture on its homology generalizing the fundamental exact sequences for Brauer groups of global fields. We prove the conjecture over a finite field assuming resolution of singularities. Thanks to a recently established result on resolution of singularities for embedded surfaces, it implies the unconditional vanishing of the homology up to degree 4 for X projective …

The Motivic Cohomology of Stiefel Varieties

The main result of this paper is a computation of the motivic cohomology of varieties of n \times m-matrices of of rank m, including both the ring structure and the action of the reduced power operations. The argument proceeds by a comparison of the general linear group-scheme with a Tate suspension of a space which is A1-equivalent to projective n - 1-space with a disjoint basepoint.

A commutative P^1-spectrum representing motivic cohomology over Dedekind domains

We construct a motivic Eilenberg-MacLane spectrum with a highly structured multiplication over smooth schemes over Dedekind domains which represents Levine's motivic cohomology. The latter is defined via Bloch's cycle complexes. Our method is by gluing p-completed and rational parts along an arithmetic square. Hereby the finite coefficient spectra are obtained by truncated étale sheaves (relying on the now proven Bloch-Kato conjecture) and a variant of Geisser's version of syntomic cohomology, and the rational spectra are the ones which represent Beilinson motivic cohomology. As an application…

On extension of the motivic cohomology beyond smooth schemes

We construct an algebraic-cycle based model for the motivic cohomology on the category of schemes of finite type over a field, where schemes may admit arbitrary singularities and may be non-reduced. We show that our theory is functorial on the category, that it detects nilpotence, and that its restriction to the subcategory of smooth schemes agrees with the pre-existing motivic cohomology theory, which is the higher Chow theory of S. Bloch (Adv. Math., 1986). A few structures and applications are discussed.