Quantum flag varieties, equivariant quantum D-modules and localization of quantum groups

Let \Oq(G) be the algebra of quantized functions on an algebraic group $G$ and \Oq(B) its quotient algebra corresponding to a Borel subgroup $B$ of $G$. We define the category of sheaves on the "quantum flag variety of $G$" to be the \Oq(B)-equivariant \Oq(G)-modules and proves that this is a proj-category. We construct a category of equivariant quantum $\mathcal{D}$-modules on this quantized flag variety and prove the Beilinson-Bernsteins localization theorem for this category in the case when $q$ is not a root of unity

Higher Auslander-Reiten sequences and tt-structures

Let $R$ be an artin algebra and $\mathcal{C}$ an additive subcategory of $\operatorname{mod}(R)$. We construct a $t$-structure on the homotopy category $\operatorname{K}^{-}(\mathcal{C})$ whose heart $\mathcal{H}_{\mathcal{C}}$ is a natural domain for higher Auslander-Reiten (AR) theory. The abelian categories $\mathcal{H}_{\operatorname{mod}(R)}$ (which is the natural domain for classical AR theory) and $\mathcal{H}_{\mathcal{C}}$ interact via various functors. If $\mathcal{C}$ is functorially finite then $\mathcal{H}_{\mathcal{C}}$ is a quotient category of $\mathcal{H}_{\operatorname{mod}(R)}$. We illustrate the theory with two examples: Iyama developed a higher AR theory when $\mathcal{C}$ is a maximal $n$-orthogonal subcategory, see \cite{I}. In this case we show that the simple objects of $\mathcal{H}_{\mathcal{C}}$ correspond to Iyama's higher AR sequences and derive his higher AR duality from the existence of a Serre functor on the derived category $\operatorname{D}^b(\mathcal{H}_{\mathcal{C}})$. The category $\mathcal{O}$ of a complex semi-simple Lie algebra $\mathfrak{g}$ fits into higher AR theory by considering $R$ to be the coinvariant algebra of the Weyl group of $\mathfrak{g}$.Comment: 26 pages, accepted for publication in Journal of Algebra 201

Global quantum differential operators on quantum flag manifolds, theorems of Duflo and Kostant

We give a short new proof for the theorem that global sections of the sheaf of quantum differential operators on a quantum flag manifold are given by the quantum group. As corollaries we retrieve Joseph and Letzter's quantum versions of classical enveloping algebra theorems of Duflo and Kostant. We also describe the center of the ad-integrable part of the quantum group and the adjoint Lie algebra action on it.Comment: 14 pages, fixed some error

Projective and Whittaker functors on category O\mathcal{O}

We show that the Whittaker functor on a regular block of the BGG-category $\mathcal{O}$ of a semisimple complex Lie algebra can be obtained by composing a translation to the wall functor with Soergel and Mili\v{c}i\'{c}'s equivalence between the category of Whittaker modules and a singular block of $\mathcal{O}$. We show that the Whittaker functor is a quotient functor that commutes with all projective functors and endomorphisms between them.Comment: 14 page

Endomorphisms of quantized Weyl algebras

Belov-Kanel and Kontsevich conjectured that the group of automorphisms of the n'th Weyl algebra and the group of polynomial symplectomorphisms of C^2 are canonically isomorphic. We discuss how this conjecture can be approached by means of (second) quantized Weyl algebras at roots of unity

Koszul duality for parabolic and singular category

Abstract. This paper deals with a generalization of the “Koszul duality theorem” for the Bernstein-Gelfand-Gelfand category O over a complex semisimple Lie-algebra, established by Beilinson, Ginzburg and Soergel in Koszul duality patterns in representation theory, J. Amer. Math. Soc. 9 (1996), 473– 527. In that paper it was proved that any “block ” in O, determined by an integral, but possibly singular weight, is Koszul (i.e. equivalent to the category of finitely generated modules over some Koszul ring) and, moreover, that the “Koszul dual ” of such a block is isomorphic to a “parabolic subcategory ” of the trivial block in O. We extend these results to prove that a parabolic subcategory of an integral and (possibly) singular block in O is Koszul and we also calculate the Koszul dual of such a category. 1