Quantum Algebra And Topology

A new method for deriving universal Ř matrices from braid group representation is discussed. In this case, universal Ř operators can be defined and expressed in terms of products of braid group generators. The advantage of this method is that matrix elements of Ř are rank independent, and leaves multiplicity problem concerning coproducts of the corresponding quantum groups untouched. As examples, Ř matrix elements of [1]×[1] , [2]×[2] , [ 1 2 ]×[ 1 2 ] , and [21]×[21] with multiplicity two for A n , and [1]×[1] for B n , C n , and D n type quantum groups, which are related to Hecke algebra and Birman-Wenzl algebra, respectively, are derived by using this method.

Braided deformations of (symmetric) monoidal categories are related to Vassiliev theory by a direct generalization of well-known results relating "quantum" knot invariants to Vassiliev invariants. The deformation theory of braidings is subsumed by the deformation theory of monoidal functors, which proves surprisingly rich: the deformation complex of a monoidal functor has the same structure as the deformation complex of an algebra, including a pre-Lie structure, from which it is see that the problem of deforming monoidal functors (including braidings) is purely cohomological in nature.

We introduce braided Lie bialgebras as the infinitesimal version of braided groups. They are Lie algebras and Lie coalgebras with the coboundary of the Lie cobracket an infinitesimal braiding. We provide theorems of transmutation, Lie biproduct, bosonisation and double-bosonisation relating braided Lie bialgebras to usual Lie bialgebras. Among the results, the kernel of any split projection of Lie bialgebras is a braided-Lie bialgebra. The Kirillov-Kostant Lie cobracket provides a natural braided-Lie bialgebra on any complex simple Lie algebra g , as the transmutation of the Drinfeld-Sklyanin Lie cobracket. Other nontrivial braided-Lie bialgebras are associated to the inductive construction of simple Lie bialgebras along the C and exceptional series.

We study the restrictions of simple modules of Ariki-Koike algebras $\H_m(\v)$ with set of parameters $\v= (\zeta;\zeta^{v_0},... ,\zeta^{v_{l-1}})$, where ζ is an n th root of unity, to their subalgebras $\H_{m-j}(\v)$. Using a theorem of Ariki and the crystal basis theory of Kashiwara, we relate this problem to the calculation of tensor product multiplicities of highest weight irreducible representations of the affine Lie algebra A (1) n−1 . These multiplicities have a combinatorial description in terms of higher level paths or highest-lift multipartitions. This enables us to solve the Jantzen-Seitz problem for Ariki-Koike algebras, that is, to determine which irreducible representations of $\H_m(\v)$ restrict to irreducible representations of $\H_{m-1}(\v)$. From a combinatorial point of view, this problem is identical to that of computing the tensor product of an A (1) n−1 -module of level l and one of level 1. We also consider natural generalisations of the Jantzen-Seitz problem corresponding to the product of a level l module by a level l ′ >1 module, and from the commutativity of tensor products, we deduce a remarkable symmetry between the generalised Jantzen-Seitz conditions and the sets of parameters of the Ariki-Koike algebras.

Using the isomorphism between highest weight U_q(sl_2)-modules and homologies of certain local systems on the configuration spaces, constructed by Varchenko, we give a geometric construction of the dual of the Lusztig's canonical basis in a tensor product of irreducible finite-dimensional U_q(sl_2)-modules.

We extend the Capelli identities (1890) from the Lie algebra g l N to the other two classical Lie algebras s o N and s p N . We employ the theory of reductive dual pairs due to Howe. Our technique comes from the representation theory of Yangians.

A new notion of Cartan pairs as a substitute of notion of vector fields in noncommutative geometry is proposed. The correspondence between Cartan pairs and differential calculi is established.

In this paper we review the recently proposed path-integral counterpart of the Koopman-von Neumann operatorial approach to classical Hamiltonian mechanics. We identify in particular the geometrical variables entering this formulation and show that they are essentially a basis of the cotangent bundle to the tangent bundle to phase-space. In this space we introduce an extended Poisson brackets structure which allows us to re-do all the usual Cartan calculus on symplectic manifolds via these brackets. We also briefly sketch how the Schouten-Nijenhuis, the Frölicher- Nijenhuis and the Nijenhuis-Richardson brackets look in our formalism.

We give a new realization of Y(s l 3 ) via Cartan-Weyl elements. An algebraic description of Yangian Double DY(s l 3 ) , explicit comultiplication formulas and universal R-matrix are obtained in these terms.

Cartan-Weyl basis for the quantum affine superalgebra U_q(^osp(1|2)) is constructed in an explicit form.