“…Boundary problems related to (1.1), (1.2), but under C ∞ conditions have been the subject of investigation in both 20 and 10. In 20 various results pertaining to the resolvent operator are derived, while in 10 a priori estimates are established for solutions for the case where \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\Omega =\mathbb {R}^n_+$\end{document} and \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\Gamma = \mathbb {R}^{n-1}$\end{document}. However, because of the restrictions imposed, both of these papers are not able to deal with the important case when \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$s_j = t_j = t^{\prime }_j$\end{document} for j = 1, …, N (here \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\big \lbrace t^{\prime }_j\big \rbrace _1^N$\end{document} denotes a monotonic decreasing sequance of positive integers) and the boundary conditions are of Dirichlet type (see 4, Section 2], 15, p. 448]).…”