Existence and uniqueness of solutions of some abstract degenerate nonlinear equations

Abstract

The nonlinear abstract differential equation $$ \frac{d}{dt}(Ay)+By(t)=F(t,Ky),\quad 0\le t\le\tau, $$ where $A,B,K$ are linear closed operators from a complex Banach space $Y$ into a Banach space $X$ is considered. The main assumption reads that the point $\xi =0$ is a polar singularity of the resolvent $(T-\xi I)^{-1}$, where $T=A(\lambda A+B)^{-1}$, $\lambda$ being a regular point of the operator pencil $\lambda A+B$. Mainly the case of a simple pole and of a second order pole are considered. Some examples of application to concrete partial differential equations are given. In particular, we show that the results work for mathematical models of nonlinear electrical networks.