| Absztrakt: | The authors consider a system of nonlinear integro-differential
equations of the form $$x'(t)=Dx(t)+\int\sp \infty\sb{-\infty}[d\sb
sE(t,s)]g(x(t+s))+f(t,x(t)),$$ where $D$ is an $(n\times n)$-constant
matrix, the function $Q(t):=\int\sp \infty\sb{-\infty}\vert d\sb
sE(t,s)\vert$ is continuous ($\vert\cdot\vert$ denotes the matrix
norm) and $E(t,s)$, $f(t,x)$ are $T$-periodic for every $s\in
R$, $x\in R\sp n$. The authors give conditions guaranteeing the
existence of $T$- periodic solutions.}
\RV{A.H.Nasr (Cairo) |