Some discontinuous functional differential equation and its connection to smoothness of composition operators in $L^p$

TL;DR

This paper explores how the regularity of history functionals influences the dependence of solutions on initial conditions in delay differential equations within $L^p$ spaces, highlighting the role of composition operators.

Contribution

It establishes the connection between the smoothness of composition operators and the continuous dependence of solutions on initial data for retarded functional differential equations.

Findings

Dependence of solutions is linked to the regularity of history functionals.

Discontinuity of history functionals is analyzed in relation to composition operators.

Smoothness of composition operators influences solution dependence.

Abstract

The objective of this paper is to deepen the understanding of the connection between the continuous and smooth dependence of solutions on initial conditions and the regularity of the history functionals for retarded functional differential equations. We consider some differential equation with a single constant delay with the history space of $L^p$-type and obtain the above dependence result by assuming the growth rate of the nonlinearity and its derivative. The corresponding history functional is discontinuous, and it becomes clear that there are the continuity and the smoothness of the composition operators (also called the superposition operators or the Nemytskij operators) between $L^p$-spaces behind the dependence results.