@article{Ptashnik_Symotyuk_2003, title={Multipoint Problem for Nonisotropic Partial Differential Equations with Constant Coefficients}, volume={55}, url={https://umj.imath.kiev.ua/index.php/umj/article/view/3902}, abstractNote={We investigate the well-posedness of a problem with multipoint conditions with respect to a chosen variable <em class="a-plus-plus">t</em> and periodic conditions with respect to coordinates <em class="a-plus-plus">x</em> <sub class="a-plus-plus">1</sub>,..., <em class="a-plus-plus">x</em> <sub class="a-plus-plus">p</sub> for a nonisotropic (concerning differentiation with respect to <em class="a-plus-plus">t</em> and <em class="a-plus-plus">x</em> <sub class="a-plus-plus">1</sub>,..., <em class="a-plus-plus">x</em> <sub class="a-plus-plus">p</sub>) partial differential equation with constant complex coefficients. We establish conditions for the existence and uniqueness of a solution of this problem and prove metric theorems on lower bounds for small denominators appearing in the course of the construction of its solution.}, number={2}, journal={Ukrainsâ€™kyi Matematychnyi Zhurnal}, author={Ptashnik, B. I. and Symotyuk, M. M.}, year={2003}, month={Feb.}, pages={241-254} }