The Zhang Transformation and U q (osp(1,2l))-Verma Modules Annihilators

R. B. Zhang found a way to link certain formal deformations of the Lie algebra o(2l+1) and the Lie superalgebra osp(1,2l). The aim of this article is to reformulate the Zhang transformation in the context of the quantum enveloping algebras à la Drinfeld and Jimbo and to show how this construction can explain the main theorem of Gorelik and Lanzmann: the annihilator of a Verma module over the Lie superalgebra osp(1,2l) is generated by its intersection with the centralizer of the even part of the enveloping algebra.     

The Yang-Mills measure in the Kauffman bracket skein module

For each closed, orientable surface , we construct a local, diffeomorphism invariant trace on the Kauffman bracket skein module . The trace is defined when |t| is neither 0 nor 1, and at certain roots of unity. At t = − 1, the trace is integration against the symplectic measure on the SU(2) character variety of the fundamental group of . Received: June 2, 2000     

A Hierarchy of Integrable Nonlinear Lattice Equations and New Integrable Symplectic Map

A discrete spectral problem is discussed, and a hierarchy of integrable nonlinear lattice equations related tothis spectral problem is devised. The new integrable symplectic map and finite-dimensional integrable systems are givenby nonlinearization method. The binary Bargmann constraint gives rise to a Backlund transformation for the resultingintegrable lattice equations.     

Existence of Symplectic Structures on Torus Bundles Over Surfaces

Let E be the total space of a locally trivial torus bundle over a surface Σ_g of genus g > 1. Using Seiberg–Witten theory and spectral sequences, we prove that E carries a symplectic structure if and only if the homology class of the fiber [T²] is nonzero in H₂(E, ℝ). Mathematics Subject Classifications (2000): 53D05, 57R57, 55R20.     

Einstein Metrics,Symplectic Minimality,and Pseudo-Holomorphic Curves

An alternative proof of the uniformization theorem for compact two-dimensional riemannian surfaces of genus 0 is proved via the direct methods of the calculus of variation as a minimum problem of the metric-dependent Dirichlet energy in the class of those maps with degree 1. Because of the conformal invariance of the energy-functional and the non compactness of the conformal group on S², concentration of mass for sequences can occur and spheres can split off. Nevertheless this is not the case for appropriate conformaly retransformed minimizing sequences. The main argument is the verification of a condition of the Douglas-type.     

Hermitian Star Products are Completely Positive Deformations

Let M be a Poisson manifold equipped with a Hermitian star product. We show that any positive linear functional on C^∞(M) can be deformed into a positive linear functional with respect to the star product.     

Asymptotic and Numerical Analyses for Mechanical Models of Heat Baths

A mechanical model of a particle immersed in a heat bath is studied, in which a distinguished particle interacts via linear springs with a collection of n particles with variable masses and random initial conditions; the jth particle oscillates with frequency j ^p , where p is a parameter. For p>1/2 the sequence of random processes that describe the trajectory of the distinguished particle tends almost surely, as n, to the solution of an integro-differential equation with a random driving term; the mean convergence rate is 1/n ^p–1/2. We further investigate whether the motion of the distinguished particle can be well approximated by an integration scheme—the symplectic Euler scheme—when the product of time step h and highest frequency n ^p is of order 1, that is, when high frequencies are underresolved. For 1/2<p<1 the numerical solution is found to converge to the exact solution at a reduced rate of |log h| h ^2–1/p . These results shed light on existing numerical data.     

Quasi-Lie Bialgebroids and Twisted Poisson Manifolds

We develop a theory of quasi-Lie bialgebroids using a homological approach. This notion is a generalization of quasi-Lie bialgebras, as well as twisted Poisson structures with a 3-form background which have recently appeared in the context of string theory, and were studied by evera and Weinstein using a different method.     

Nondegenerate Monge–Ampère Structures in Dimension 6

We define a nondegenerate Monge–Ampère structure on a six-dimensional manifold as a pair (, ), such that is a symplectic form and is a 3-differential form which satisfies =0 and which is nondegenerate in the sense of Hitchin. We associate with such a pair a generalized almost (pseudo) Calabi–Yau structure and we study its integrability from the point of view of Monge–Ampère operators theory. The result we prove appears as an analogue of Lychagin and Roubtsov theorem on integrability of the almost complex or almost product structure associated with an elliptic or hyperbolic Monge–Ampère equation in dimension 4. We study from this point of view the example of the Stenzel metric on T*S ³.     

Left Adjoint for Booleanization

Left adjoint for Booleanization in suitable categories of frames is constructed.