Let G=H be an irreducible globally hyperbolic semisimple symmetric space, and let S G be a subsemigroup containing H not isolated in S. We show that if S o 6 = then there are H-invariant minimal and maximal cones C min C max in the tangent space at the origin such that H exp C min S HZ K (a) exp C max. A double coset decomposition of the group G in terms of Cartan subspaces and the group H is p...

This paper studies two homogenizations of the down-up algebras introduced in [1]. We show that in all cases the homogenizing variable is not a zero-divisor, and that when the parameter β is non-zero, the homogenized down-up algebra is a Noetherian domain and a maximal order, and also Artin-Schelter regular, Auslander regular, and Cohen-Macaulay. We show that all homogenized down-up algebras hav...

We consider improvements of Dirichlet’s Theorem on space of matrices Mm,n(R). It is shown that for a certain class of fractals K ⊂ [0, 1] ⊂ Mm,n(R) of local maximal dimension Dirichlet’s Theorem cannot be improved almost everywhere. This is shown using entropy and dynamics on homogeneous spaces of Lie groups.

In this paper, we study q-Sturm-Liouville operators. We construct a space of boundary values of the minimal operator and describe all maximal dissipative, maximal accretive, self-adjoint and other extensions of q-Sturm-Liouville operators in terms of boundary conditions. Then we prove a theorem on completeness of the system of eigenfunctions and associated functions of dissipative operators by ...

We consider the vector-valued extension of the Fefferman–Stein– Strömberg sharp maximal inequality under growth condition. As an application we obtain a vector-valued extension of the boundedness of the commutator. Furthermore, we prove the boundedness of the commutator. 2000 Mathematics Subject Classification: Primary 42B35; Secondary 42B25.

Convolution type Calderón-Zygmund singular integral operators with rough kernels p.v. Ω(x)/|x| are studied. A condition on Ω implying that the corresponding singular integrals and maximal singular integrals map L → L for 1 < p < ∞ is obtained. This condition is shown to be different from the condition Ω ∈ H1(Sn−1).

If f : [0, 1] → R is strictly increasing and continuous define Tfx = f(x) (mod 1). A transformation T̃ : [0, 1] → [0, 1] is called ε-close to Tf , if T̃ x = f̃(x) (mod 1) for a strictly increasing and continuous function f̃ : [0, 1] → R with ‖f̃ − f‖∞ < ε. It is proved that the topological pressure p(Tf , g) is lower semi-continuous, and an upper bound for the jumps up is given. Furthermore the cont...

On any compact Riemannian manifold (M,g) of dimension n, the Lnormalized eigenfunctions {φλ} satisfy ||φλ||∞ ≤ Cλ n−1 2 where −∆φλ = λ 2φλ. The bound is sharp in the class of all (M, g) since it is obtained by zonal spherical harmonics on the standard n-sphere S. But of course, it is not sharp for many Riemannian manifolds, e.g. flat tori R/Γ. We say that S, but not R/Γ, is a Riemannian manifol...

We compute symmetry algebras for nonlinear Schrödinger equations which contain an imaginary nonlinearity as derived by Doebner and Goldin and certain real nonlinearities not depending on the derivatives. In the three-dimensional case we find the maximal symmetry algebras for equations of this type. Admitting other imaginary nonlinearities does lead to similar symmetry algebras. These symmetries...

The problem of nonparametric regression is addressed, and a kernel smoothing estimator is proposed which has favorable asymptotic performance (bias, variance, and mean squared error). The proposed class of kernels is characterized by a Fourier transform which is flat near the origin and infinitely differentiable. This property allows the bias of the estimate to decrease at the maximal rate with...