arXiv subjects
Publications and source records attributed to Masaki Kashiwara.
We show that the finite-dimensional fundamental module over a quantized affine algebra is isomorphic to a Demazure module of a higest weight module of level one as a module over a quantized classical universal enveloping algebra.
In this paper, we develop the crystal basis theory for quantum generalized Kac-Moody algebras. For a quantum generalized Kac-Moody algebra $U_q(\mathfrak g)$, we first introduce the category $\mathcal O_{int}$ of $U_q(\mathfrak g)$-modules and prove its semisimplicity. Next, we define the notion of crystal bases for $U_q(\mathfrak g)$-modules in the category $\mathcal O_{int}$ and for the subalgebra $U_q^-(\mathfrak g)$. We then prove the tensor product rule and the existence theorem for crystal bases. Finally, we construct the global bases for $U_q(\mathfrak g)$-modules in the category $\mathcal O_{int}$ and for the subalgebra $U_q^-(\mathfrak g)$.
We give the description of the t-structure on the derived category of regular holonomic D-modules corresponding to the trivial t-structure on the derived category of constructible sheaves via Riemann-Hilbert correspondence. We give also the condition for a decreasing sequence of families of supports to give a t-structure on the derived category of coherent O-modules.
Comparing vanishing of local cohomology in zero and positive characteristic, we give an example of a D-module on a Grassmann variety in positive characteristic with non-vanishing first cohomology group. This is a counterexample to D-affinity and the Beilinson-Bernstein equivalence for flag manifolds in positive characteristic.
Using a result of J-M. Bony, we prove the weak involutivity of truncated microsupports. More precisely, given a sheaf $F$ on a real manifold and an integer $k$, if two functions vanish on the truncated microsupport $Ss_k(F)$, then so does their Poisson bracket.
We study the truncated microsupport $Ss_k$ of sheaves on a real manifold. Applying our results to the case of $F=RHom_D(M,O)$, the complex of holomorphic solutions of a coherent $D$-module $M$, we show that $Ss_k(F)$ is completely determined by the characteristic variety of $M$. As an application, we obtain an extension theorem for the sections of $H^j(F)$, $j<d$, defined on an open subset whose boundary is non characteristic outside of a complex analytic subvariety of codimension $d$. We also give a characterization of the perversity for ${\bf C}$-constructible sheaves in terms of their truncated microsupports.
We shall give various realizations of crystals. One of them is a monome realization introduced by Nakajima.
We define the notions of micro-support and regularity for ind-sheaves, and prove their invariance by contact transformations. We apply the results to the ind-sheaves of temperate holomorphic solutions of D-modules. We prove that the micro-support of such an ind-sheaf is the characteristic variety of the corresponding D-module and that the ind-sheaf is regular if the D-module is regular holonomic.
Let $X$ be a complex manifold, $V$ a smooth involutive submanifold of $T^*X$, $\cal M$ a microdifferential system regular along $V$, and $F$ an $\mathbb{R}$-constructible sheaf on $X$. The complex of temperate microfunction solutions of $\cal M$ associated with $F$ is now well understood. In this paper we study the temperate case and give a bound to the micro-support of the temperate microfunction solution sheaves and solve the Cauchy problem under suitable hyperbolicity conditions.
We shall give a description of the intersection cohomology groups of the Schubert varieties in partial flag manifolds over symmetrizable Kac-Moody Lie algebras in terms of parabolic Kazhdan-Lusztig polynomials introduced by Deodhar.
This is an announcement of a long paper in progress. On a locally compact space, we introduce the stack of ind-sheaves (ind-objects of the category of sheaves with compact support) and construct the analogous of the usual six operations on sheaves. As an application, we treat, in the formalism of ind-sheaves, functions with growth conditions such as the ``tempered holomorphic functions'' on a complex manifold. We also construct a microlocalization functor from the category of sheaves on a manifold to that of ind-sheaves on the cotangent bundle.
We shall derive Kazhdan-Lusztig type character formula for the irreducible modules with arbitrary non-critical highest weights over affine Lie algebras from the rational case by using the translation functor, the Enright functor and Jantzen's deformation argument.
We develop a crystal base theory for the general linear Lie superalgebra $gl(m,n)$. We prove that any irreducible $U_q(gl(m,n))$-module in some category has a crystal base, and prove that its associated crystal base is parameterized by semistandard tableaux.
Motivated by the work of Nakayashiki on the inhomogeneous vertex models of 6-vertex type, we introduce the notion of crystals with head. We show that the tensor product of the highest weight crystal of level k and the perfect crystal of level l is isomorphic to the tensor product of the perfect crystal of level l-k and the highest weight crystal of level k.
We realize the crystal associated to the quantized enveloping algebras with a symmetric generalized Cartan matrix as a set of Lagrangian subvarieties of the cotangent bundle of the quiver variety. As a by-product, we give a counterexample to the conjecture of Kazhdan--Lusztig on the irreducibility of the characteristic variety of the intersection cohomology sheaves associated with the Schubert cells of type A and also to the similar problem asked by Lusztig on the characteristic variety of the perverse sheaves corresponding to canonical bases.
A general scheme for the wedge construction of q-deformed Fock spaces using the theory of perfect crystals is presented. Let $U_q(\g)$ be a quantum affine algebra. Let $V$ be a finite-dimensional $U'_q(\g)$-module with a perfect crystal base of level~$l$. Let $V_\aff\simeq V\otimes\C[z,z^{-1}]$ be the affinization of $V$, with crystal base $(L_\aff,B_\aff)$. The wedge space $V_\aff\wedge V_\aff$ is defined as the quotient of $V_\aff\otimes V_\aff$ by the subspace generated by the action of $U_q(\g)[z^a\otimes z^b +z^b\otimes z^a]_{a,b\in\Z}$ on $v\otimes v$ ($v$ an extremal vector). The wedge space $\bigwedge^r V_\aff$ ($r\in\N$) is defined similarly. Normally ordered wedges are defined by using the energy function $H:B_\aff\otimes B_\aff\to\Z$. Under certain assumptions, it is proved that normally ordered wedges form a base of $\bigwedge^r V_\aff$. A q-deformed Fock space is defined as the inductive limit of $\bigwedge^r V_\aff$ as $r\to\infty$, taken along the semi-infinite wedge associated to a ground state sequence. It is proved that normally ordered wedges form a base of the Fock space and that the Fock space has the structure of an integrable $U_q(\g)$-module. An action of the bosons, which commute with the $U'_q(\g)$-action, is given on the Fock space. It induces the decomposition of the q-deformed Fock space into the tensor product of an irreducible $U_q(\g)$-module and a bosonic Fock space. As examples, Fock spaces for types $A^{(2)}_{2n}$, $B^{(1)}_n$, $A^{(2)}_{2n-1}$, $D^{(1)}_n$ and $D^{(2)}_{n+1}$ at level~1 and $A^{(1)}_1$ at level~$k$ are constructed. The commutation relations of the bosons in each of these cases are calculated, using two point functions of vertex operators.
A decomposition of the level-one $q$-deformed Fock representations of $\uqn$ is given. It is found that the action of $\upqn$ on these Fock spaces is centralized by a Heisenberg algebra, which arises from the center of the affine Hecke algebra $\widehat{H}_N$ in the limit $N \rightarrow \infty$. The $q$-deformed Fock space is shown to be isomorphic as a $\upqn$-Heisenberg-bimodule to the tensor product of a level-one irreducible highest weight representation of $\upqn$ and the Fock representation of the Heisenberg algebra. The isomorphism is used to decompose the $q$-wedging operators, which are intertwiners between the $q$-deformed Fock spaces, into constituents coming from $\upqn$ and from the Heisenberg algebra.