Shahmurov, Rishad2024-05-252024-05-252010300022-03961090-273210.1016/j.jde.2010.03.0292-s2.0-77952950770https://doi.org/10.1016/j.jde.2010.03.029https://hdl.handle.net/20.500.14517/664Here we study Dirichlet and Neumann problems for a special Helmholtz equation on an annulus. Our main aim is to measure smoothness of solutions for the boundary datum in Besov spaces. We shall use operator theory to solve this problem. The most important advantage of this technique is that it enables to consider equations in vector-valued settings. It is interesting to note that optimal regularity of this problem will be a special case of our main result. (C) 2010 Elsevier Inc. All rights reserved.eninfo:eu-repo/semantics/closedAccessModified Helmholtz equationDifferential-operator equationsBoundary value problemsInterpolation of Banach spacesSemigroup estimatesOperator-valued Fourier multipliersArticleQ1Q12493526550WOS:000278873500002