Some Classes of Linear Conjugation Problems for a Four-Dimensional Vector That Are Solvable in Closed Form.

We consider the structure of the set of piecewise meromorphic solutions of a homogeneous linear conjugation problem for a four-dimensional vector. We show that in the presence of three piecewise meromorphic solutions to the linear conjugation problem it is possible to construct a canonical system of solutions to the linear conjugation problem and distinguish some classes of problems that are solvable in closed form. [ABSTRACT FROM AUTHOR]