Euler complexes and geometry of modular varieties

On Euler characteristics of Selmer groups for abelian varieties over global function fields

Let $F$ be a global function field of characteristic $p>0$, $K/F$ an $\ell$-adic Lie extension ($\ell\neq p$) and $A/F$ an abelian variety. We provide Euler characteristic formulas for the $Gal(K/F)$-module $Sel_A(K)_\ell$.

关于欧拉系统和涅科瓦尔-塞勒复形

On Euler systems and Nekovář-Selmer complexes

本文发展了相对于p-进表示的涅科瓦尔-塞勒复形的欧拉和科利瓦金系统理论，证明了新的Kato广义伊瓦索主猜想案例，并加强了CM椭圆曲线的 Birch-Swinnerton-Dyer 猜想结果。

Construction of Anti-Cyclotomic Euler Systems of Abelian Varieties Associated to $X_1(N)$

Let $K$ be an imaginary quadratic field, $N$ be a positive integer, $f(z)$ be a newform of level $Γ_1(N)$, and $A_f$ be the abelian variety associated to $f$. For each $τ\in K$ ($\operatorname{Im} τ>0$), we construct a certain point $P_τ$ on $A_f$ defined over an extended ring class field of $K$ of level $N$. Our construction generalizes Birch's construction of the Heegner points to the abelian varieties associated to modular forms of level $Γ_1(N)$ and nontrivial character. Then, we show that $P_τ$'s satisfy the distribution and congruence relations of an Euler system, which implies that it s…

On the dihedral Euler characteristics of Selmer groups of abelian varieties

This note shows how to use the framework of Euler characteristic formulae to study Selmer groups of abelian varieties in certain dihedral or anticyclotomic extensions of CM fields via Iwasawa main conjectures, and in particular how to verify the p-part of the refined Birch and Swinnerton-Dyer conjecture in this setting. When the Selmer group is cotorsion with respect to the associated Iwasawa algebra, we obtain the p-part of formula predicted by the refined Birch and Swinnerton-Dyer conjecture. When the Selmer group is not cotorsion with respect to the associated Iwasawa algebra, we give a con…

On constructing zeta elements for Shimura varieties

We present a novel axiomatic framework for establishing horizontal norm relations in Euler systems that are built from pushforwards of classes in the motivic cohomology of Shimura varieties. This framework is uniformly applicable to the Euler systems of both algebraic cycles and Eisenstein classes. It also applies to non-spherical pairs of groups that fail to satisfy a local multiplicity one hypothesis, and thus lie beyond the reach of existing methods. A key application of this work is the construction of an Euler system for the spinor Galois representations arising in the cohomology of Siege…

Intersection complexes and unramified $L$-factors

Let X be an affine spherical variety, possibly singular, and $L^+X$ its arc space. The intersection complex of $L^+X$, or rather of its finite-dimensional formal models, is conjectured to be related to special values of local unramified L-functions. Such relationships were previously established in Braverman-Finkelberg-Gaitsgory-Mirkovic for the affine closure of the quotient of a reductive group by the unipotent radical of a parabolic, and in Bouthier-Ngo-Sakellaridis for toric varieties and L-monoids. In this paper, we compute this intersection complex for the large class of those spherical …

On finite arithmetic simplicial complexes

We compute the Euler-Poincaré characteristic of quotients of the Bruhat-Tits building of PGL(n) under the action of arithmetic groups arising from central division algebras over rational function fields of positive characteristic. We use this result to determine the structure of the quotient simplicial complex in certain cases.

Kottwitz's nearby cycles conjecture for a class of unitary Shimura varieties

This paper proves that the nearby cycles complexes on a certain family of PEL local models are central with respect to the convolution product of sheaves on the corresponding affine flag varieties. As a corollary, the semisimple trace functions defined using the action of Frobenius on those nearby cycles complexes are, via the sheaf-function dictionary, in the centers of the corresponding Iwahori-Hecke algebras. This is commonly referred to as Kottwitz's Conjecture. The reductive groups associated to the PEL local models under consideration are unramified unitary similitude groups with even di…

Grothendieck–Witt 环上的幂结构与动机 Euler 特征

Power structures on the Grothendieck--Witt ring and the motivic Euler characteristic

本文在域 $k$ 的 Grothendieck–Witt 环上构造了与簇的对称幂和动机 Euler 特征相容的幂结构，并证明在维数 $0$ 的簇上该结构与已知幂结构相容。