On periodic solutions of a class of functional-differential equations with deviating argument and periodic coefficients (Q1094577)

The problem on nr-periodic solutions of the linear difference- differential equation of the form \[ \sum^{n}_{i=1}\sum^{s}_{j=0}a_{ij}(t)x^{(j)}(t+ir)+\sum^{n}\;sb{i=1}\sum^{s}_{j=0}b_{ij}(t)x^{(j)}(ir-t)=y(t), \] where \(a_{ij}\), \(b_{ij}\) and y are continuous nr-periodic functions, is considered. The author reduces this problem to an analogous problem for ODE and investigates algebraic properties of the set of solutions.