# Minimal and maximal solutions of fourth order iterated differential equations with singular nonlinearity

## Kristína Rostás

Address: Department of Mathematics, Comenius University, Mlynská dolina, Bratislava, Slovakia

E-mail: kristina.rostas@fmph.uniba.sk

Abstract: In this paper we are concerned with sufficient conditions for the existence of minimal and maximal solutions of differential equations of the form
\[ L_{4}y+f(t,y)=0\,, \]
where $L_{4}y$ is the iterated linear differential operator of order $4$ and $f\colon [a,\infty )\times (0,\infty )\rightarrow (0,\infty )$ is a continuous function.

AMSclassification: primary 34C10.

Keywords: iterated differential equations, maximal and minimal solutions.