# Symotyuk M. M.

### Nonlocal boundary-value problem for a second-order partial differential equation in an unbounded strip

Il'kiv V. S., Symotyuk M. M., Volyanska I. I.

Ukr. Mat. Zh. - 2018. - 70, № 10. - pp. 1374-1381

The conditions of well-posedness of a nonlocal boundary-value problem are established for a second-order linear partial differential equation in an unbounded strip in the case where the real parts of the roots of its characteristic equation are different and nonzero.

### Multipoint Problem with Multiple Nodes for Partial Differential Equations

Ptashnik B. I., Symotyuk M. M.

Ukr. Mat. Zh. - 2003. - 55, № 3. - pp. 400-413

We establish conditions for the existence and uniqueness of a solution of a problem with multipoint conditions with respect to a selected variable *t* (in the case of multiple nodes) and periodic conditions with respect to *x* _{1},..., *x* _{p} for a nonisotropic partial differential equation with constant complex coefficients. We prove metric theorems on lower bounds for small denominators appearing in the course of the solution of this problem.

### Multipoint Problem for Nonisotropic Partial Differential Equations with Constant Coefficients

Ptashnik B. I., Symotyuk M. M.

Ukr. Mat. Zh. - 2003. - 55, № 2. - pp. 241-254

We investigate the well-posedness of a problem with multipoint conditions with respect to a chosen variable *t* and periodic conditions with respect to coordinates *x* _{1},..., *x* _{p} for a nonisotropic (concerning differentiation with respect to *t* and *x* _{1},..., *x* _{p}) 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.