Periodic solutions of neutral differential equation with multiple deviating arguments (Q1888533)

By means of an abstract continuation theorem of a \(k\)-set contractive set, the authors derive a new sufficient criterion for the existence of periodic solutions of NFDEs with multiple deviating arguments of the type \[ \frac{d}{dt}(x(t)-cx(t-\tau))=\sum\limits_{i=1}^n\alpha_i(t)f(x(t-\tau_i(t)))+ \sum\limits_{j=1}^m\beta_j(t)g(x'(t-\gamma_j(t)))+p(t). \]