We prove that any minimal (maximal) strongly regular surface in the threedimensional Minkowski space locally admits canonical principal parameters. Using this result, we find a canonical representation of minimal strongly regular time-like surfaces, which makes more precise the Weierstrass representation and shows more precisely the correspondence between these surfaces and holomorphic function...

We develop a general approach to the study of maximal nilpotent subsemigroups of finite semigroups. This approach can be used to recover many known classifications of maximal nilpotent subsemigroups, in particular, for the symmetric inverse semigroup, the symmetric semigroup, and the factor power of the symmetric group. We also apply this approach to obtain a classification of maximal nilpotent...

We establish some sharp maximal function inequalities for the Toeplitz type operator, which is related to certain fractional singular integral operator with general kernel. These results are helpful to investigate the boundedness of the operator on Lebesgue, Morrey and Triebel–Lizorkin spaces respectively.

We introduce two generalizations of the full inverse symmetric semigroup ISX — the inverse semigroups PIPX and P̃IPX . Both of these semigroups have the same set of elements and contain ISX . The binary operations on PIPX and P̃IPX are two natural generalizations of the multiplication of partial permutations and each of the considered operations coincides with this multiplication when restricted ...

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.