Multiplicative structure on the Hochschild cohomology of crossed product algebras

霍奇-希尔德上同调与端射的提升

Hochschild cohomology and lifts of endomorphisms

研究代数自同射何时能提升为一阶平坦提升，通过关联一阶平坦提升与自同射的霍奇-希尔德上同调类，证明自同射提升当且仅当中心上的诱导自同射保持提升后的泊松结构。

Deformations of Affine Varieties and the Deligne Crossed Groupoid

Let X be a smooth affine algebraic variety over a field K of characteristic 0, and let R be a complete parameter K-algebra (e.g. R = K[[h]]). We consider associative (resp. Poisson) R-deformations of the structure sheaf O_X. The set of R-deformations has a crossed groupoid (i.e. strict 2-groupoid) structure. Our main result is that there is a canonical equivalence of crossed groupoids from the Deligne crossed groupoid of normalized polydifferential operators (resp. polyderivations) of X to the crossed groupoid of associative (resp. Poisson) R-deformations of O_X. The proof relies on a careful …

Crossed product tensor categories

A graded tensor category over a group $G$ will be called a crossed product tensor category if every homogeneous component has at least one multiplicatively invertible object. Our main result is a description of the crossed product tensor categories, graded monoidal functors, monoidal natural transformations, and braiding in terms of coherent outer $G$-actions over tensor categories.

Crossed modules of Hopf algebras and of associative algebras and two-dimensional holonomy

After a thorough treatment of all algebraic structures involved, we address two dimensional holonomy operators with values in crossed modules of Hopf algebras and in crossed modules of associative algebras (called here crossed modules of bare algebras.) In particular, we will consider two general formulations of the two-dimensional holonomy of a (fully primitive) Hopf 2-connection (exact and blur), the first being multiplicative the second being additive, proving that they coincide in a certain natural quotient (defining what we called the fuzzy holonomy of a fully primitive Hopf 2-connection)…

Multiplicative structure of Kauffman bracket skein module quantizations

We describe, for a few small examples, the Kauffman bracket skein algebra of a surface crossed with an interval. If the surface is a punctured torus the result is a quantization of the symmetric algebra in three variables (and an algebra closely related to a cyclic quantization of $U(so_3$). For a torus without boundary we obtain a quantization of "the symmetric homologies" of a torus (equivalently, the coordinate ring of the $SL_2(C)$-character variety of $Z \oplus Z$). Presentations are also given for the four punctured sphere and twice punctured torus. We conclude with an investigation of c…

忠实平坦Hopf Galois扩张的Ştefan谱序列是乘法的

Ştefan spectral sequence for faithfully flat Hopf Galois extensions is multiplicative

本文证明忠实平坦Hopf Galois扩张的Ştefan谱序列具有乘法性，引入相关形式体系构造对应谱序列，结合比较定理完成等同，在多类代数结构上得到新乘法性结果。

Quantization, orbifold cohomology, and Cherednik algebras

We compute the Hochschild homology of the crossed product $\Bbb C[S_n]\ltimes A^{\otimes n}$ in terms of the Hochschild homology of the associative algebra $A$ (over $\Bbb C$). It allows us to compute the Hochschild (co)homology of $\Bbb C[W]\ltimes A^{\otimes n}$ where $A$ is the $q$-Weyl algebra or any its degeneration and $W$ is the Weyl group of type $A_{n-1}$ or $B_n$. For a deformation quantization $A_+$ of an affine symplectic variety $X$ we show that the Hochschild homology of $S^n A$, $A=A_+[\hbar^{-1}]$ is additively isomorphic to the Chen-Ruan orbifold cohomology of $S^nX$ with coef…

Quantum groups with projection on von Neumann algebra level

We introduce an axiomatization of the notion of a semidirect product of locally compact quantum groups and study properties. Our approach is slightly different from the one introduced in the thesis of S.~Roy and, unlike the investigations of Roy, we work within the von Neumann algebraic picture. This allows the use of powerful techniques related to crossed products by actions of locally compact quantum groups. In particular we show existence of a "braided comultiplication" on the algebra spanned by slices of "braided multiplicative unitary".

量子化辛代数簇的范畴胞腔分解

Categorical Cell Decomposition of Quantized Symplectic Algebraic Varieties

本研究证明了D模理论中柏原等价的辛类似物，建立了形变量子化模范畴的结构理论，得到范畴胞腔分解，并推导了几何表示论中相关模范畴不变量的具体结论。

Double affine Hecke algebras of rank 1 and affine cubic surfaces

We study the algebraic properties of the five-parameter family $H(t_1,t_2,t_3,t_4;q)$ of double affine Hecke algebras of type $C^\vee C_1$. This family generalizes Cherednik's double affine Hecke algebras of rank 1. It was introduced by Sahi and studied by Noumi and Stokman as an algebraic structure which controls Askey-Wilson polynomials. We show that if $q=1$, then the spectrum of the center of $H$ is an affine cubic surface $C$, obtained from a projective one by removing a triangle consisting of smooth points. Moreover, any such surface is obtained as the spectrum of the center of $H$ for s…