No Arabic abstract
In this paper, we use a new method to solve a long-standing problem. More specifically, we show that the Beurling-type theorem holds in the Bergman space $A^2_alpha(D)$ for any $-1<alpha < +infty$. That is, every invariant subspace $H$ for the shift operator $S$ on $A^2_alpha(D)$ $(-1<alpha < +infty)$ has the property $H=[Hominus zH]_{S,A^2_alphaleft(Dright)}$.
The classical Banach space $L_1(L_p)$ consists of measurable scalar functions $f$ on the unit square for which $$|f| = int_0^1Big(int_0^1 |f(x,y)|^p dyBig)^{1/p}dx < infty.$$ We show that $L_1(L_p)$ $(1 < p < infty)$ is primary, meaning that, whenever $L_1(L_p) = Eoplus F$ then either $E$ or $F$ is isomorphic to $L_1(L_p)$. More generally we show that $L_1(X)$ is primary, for a large class of rearrangement invariant Banach function spaces.
The aim of this paper is to provide characterizations of a Meir-Keeler type mapping and a fixed point theorem for the mapping in a metric space endowed with a transitive relation.
We give a complete solution to the Borel-Ritt problem in non-uniform spaces $mathscr{A}^-_{(M)}(S)$ of ultraholomorphic functions of Beurling type, where $S$ is an unbounded sector of the Riemann surface of the logarithm and $M$ is a strongly regular weight sequence. Namely, we characterize the surjectivity and the existence of a continuous linear right inverse of the asymptotic Borel map on $mathscr{A}^-_{(M)}(S)$ in terms of the aperture of the sector $S$ and the weight sequence $M$. Our work improves previous results by Thilliez [10] and Schmets and Valdivia [9].
In this paper, we prove the corona theorem for $M(D(mu_k))$ in two different ways, where $mu_k = sum_{i=1}^k a_i delta_{zeta_i}$. Then we prove that the Bass stable rank of $M(D(mu_k))$ is one.
In this paper, we introduce the Fock space over $mathbb{C}^{infty}$ and obtain an isomorphism between the Fock space over $mathbb{C}^{infty}$ and Bose-Fock space. Based on this isomorphism, we obtain representations of some operators on the Bose-Fock space and answer a question in cite{coburn1985}. As a physical application, we study the Gibbs state.