\documentclass[reqno]{amsart}
\usepackage{hyperref}

\AtBeginDocument{{\noindent\small
\emph{Electronic Journal of Differential Equations},
Vol. 2016 (2016), No. 286, pp. 1--19.\newline
ISSN: 1072-6691. URL: http://ejde.math.txstate.edu or http://ejde.math.unt.edu}
\thanks{\copyright 2016 Texas State University.}
\vspace{8mm}}

\begin{document}
\title[\hfilneg EJDE-2016/286\hfil Bounded solutions]
{Weighted pseudo almost  automorphic  solutions to
functional differential equations with infinite delay}

\author[Y. K. Chang, S. Zheng \hfil EJDE-2016/286\hfilneg]
{Yong-Kui Chang, Shan Zheng}

\address{Yong-Kui Chang \newline
School of Mathematics and Statistics,
Xidian University,
Xi'an 710071, China}
\email{lzchangyk@163.com}

\address{Shan Zheng \newline
Department of Mathematics,
Lanzhou Jiaotong University,
Lanzhou 730070, China}
\email{1318434313@qq.com}

\thanks{Submitted September 20, 2016. Published October 26, 2016.}
\subjclass[2010]{43A60, 34G20, 47D03}
\keywords{Stepanov-like weighted function;
functional differential equation;
\hfill\break\indent  pseudo almost automorphic function;
  infinite delay}

\begin{abstract}
 In this article, we first establish some results on composition of
 Stepanov-like weighted pseudo almost automorphic functions so called 
 class $r$ and class infinity  under a uniform continuity condition with 
 respect to $L^p$-norm. And then,  we study the existence and uniqueness 
 of weighted pseudo almost  automorphic solutions  to an abstract partial
 neutral functional differential equation with infinite delay with a
 Stepanov-like nonlinear term.
\end{abstract}

\maketitle
\numberwithin{equation}{section}
\newtheorem{theorem}{Theorem}[section]
\newtheorem{lemma}[theorem]{Lemma}
\newtheorem{remark}[theorem]{Remark}
\newtheorem{definition}[theorem]{Definition}
\newtheorem{corollary}[theorem]{Corollary}
\allowdisplaybreaks

\section{Introduction}

The concept of almost automorphy, which was introduced by  Bochner \cite{BS3}, as
a generalization of the classical almost periodicity
in the sense of Bohr; see for example \cite{Diabook,NG16, NG18}.
 N'Gu\'{e}r\'{e}kata and Pankov introduced the concept of Stepanov-like
almost automorphy in \cite{NG17}.
Diagana \cite{dia2} introduced the concept of Stepanov-like pseudo almost
 automorphy as a natural generalization
of the pseudo almost automorphy and an implement of the
Stepanov-like almost automorphy due to N'Gu\'{e}r\'{e}kata and
Pankov \cite{NG17}.
Blot et al \cite{BJ4} introduced the notion of weighted pseudo almost automorphic
functions with values in a Banach space.
 Xia and Fan presented the notion of Stepanov-like (or $S^p$-) weighted
pseudo almost automorphic function in \cite{xia}. To study differential
equations with delay, Zhang, Chang and N'Gu\'{e}r\'{e}kata \cite{ZR22}
further studied new types of functions so called Stepanov-like weighted
pseudo almost automorphic functions of class $r$, and Stepanov-like weighted
pseudo almost automorphic functions of class infinity.
The above mentioned concepts have
been considerably investigated and applied to various differential
equations, see \cite{abbas1,abbas2,abbas3,ZR21, DT9, DT10,ding7,flx,henr,
kavitha,ponce,sak,sak3} and the references
therein.

The main purpose of this article is to study  composition results for
Stepanov-like weighted pseudo almost automorphic functions of class $r$
and Stepanov-like weighted pseudo almost automorphic functions of class
infinity \cite{ZR22}. Considering the space of Stepanov-like weighted
pseudo almost automorphic functions of class $r$ and Stepanov-like weighted
pseudo almost automorphic functions of class infinity with an integral
norm coming from $L^p$-norm, we first prove new composition theorems
for Stepanov-like weighted pseudo almost automorphic functions of class $r$
under a uniform continuity condition with respect to the $L^p$-norm
suggested by \cite{CY7}. Similarly, we can arrive at  new composition
theorems for Stepanov-like weighted pseudo almost automorphic functions of
class infinity. And then, we apply the obtained results to prove the
existence and uniqueness of  weighted pseudo almost automorphic solutions
for the following abstract partial neutral functional-differential equation
with infinite delay under Stepanov-like nonlinear forcing term
\begin{equation}
\frac{d}{dt}(u(t)+f(t,u_{t}))=A(t)u(t)+g(t,u_{t}),\quad
t\in \mathbb{R}, \label{a1.1}
\end{equation}
where $A(t):D(A(t))\subset \mathbb{X}\to\mathbb{X}$ is a family of densely
defined closed linear operators on the domain $D=D(A(t))$, which is
independent of $t$, the history $u_{t}:(0,\infty]\to \mathbb{X}$ defined
by $u_{t}(\theta)=u(t+\theta)$, belongs to some abstract phase space
$\mathfrak{B}$ defined axiomatically, and
$f,g:\mathbb{R}\times \mathfrak{B}\to \mathbb{X}$ are some suitable functions.

The rest of this paper is organized as follows.
In Section 2, we recall some basic definitions, lemmas, and notation
 which will be used throughout this paper.
In Section 3, we establish some new results on composition of Stepanov-like
weighted pseudo almost automorphic functions of class $r$ and Stepanov-like
weighted pseudo almost automorphic functions of class infinity under
$L^p$-norm uniform continuity condition.
In Section 4, we prove the existence and uniqueness of weighted pseudo
almost automorphic solutions to the equation \eqref{a1.1} under Stepanov-like
nonlinear forcing term. An example is also given to illustrate the main results.


\section{Preliminaries}

Let $(\mathbb{X},\|\cdot\|)$ and $(\mathbb{Y},\|\cdot\|_{\mathbb{Y}})$ be two
Banach spaces and $\mathbb{N},\mathbb{R}$ stand for sets of natural numbers
and real numbers, respectively. To facilitate discussions later, we
 introduce the following notation:

$\bullet$ $BC(\mathbb{R},\mathbb{X})$
(respectively, $BC(\mathbb{R}\times\mathbb{Y},\mathbb{X})$):
The Banach spaces of bounded continuous function from $\mathbb{R}$ to
$\mathbb{X}$ (respectively, from $\mathbb{R}\times\mathbb{Y}$ to $\mathbb{X}$)
with the sup norm.

$\bullet$ $L^p(\mathbb{R},\mathbb{X})$: The space of all classes of
equivalence (with respect to the equality almost everywhere on $\mathbb{R}$)
of measurable function $f:\mathbb{R}\to\mathbb{X}$ such that
$\|f\|\in L^p(\mathbb{R},\mathbb{R})$.

$\bullet$ $L^p_{\rm loc}(\mathbb{R},\mathbb{X})$: The space of all classes
of equivalence of measurable function $f:\mathbb{R}\to\mathbb{X}$ such that
the restriction of $f$ to every bounded subinterval of $\mathbb{R}$ is
in $L^p(\mathbb{R},\mathbb{X})$.

$\bullet$ $\mathfrak{L}(\mathbb{X},\mathbb{Y})$:
Stands for the Banach space of bounded linear operators from $\mathbb{X}$
to $\mathbb{Y}$ equipped with its natural topology.

\begin{definition}[\cite{NG18}] \rm
 A continuous function $f:\mathbb{R}\to\mathbb{X}$ is
said to be almost automorphic if for every sequence of real numbers $
\{s_n'\}_{n\in\mathbb{N}}$ there exists a subsequence $
\{s_n\}_{n\in\mathbb{N}}$ such that
\begin{equation*}
g(t):=\lim_{n\to\infty}f(t+s_n)
\end{equation*}
is well defined for each $t \in \mathbb{R}$, and
\begin{equation*}
\lim_{n\to\infty}g(t-s_n)=f(t)
\end{equation*}
for each $t \in \mathbb{R}$. The collection of all such functions will be
denoted by $AA(\mathbb{X})$.
\end{definition}

\begin{definition}[\cite{LJ15,NG18}] \rm
 A continuous function $f:\mathbb{R}\times\mathbb{X}
\to\mathbb{X}$ is said to be almost automorphic if $f(t,x)$ is
almost automorphic for each $t\in \mathbb{R}$ uniformly for all $x\in \mathbb{B}$,
where $\mathbb{B}$ is any bounded subset of $\mathbb{X}$. The collection of all such
functions will be denoted by $AA(\mathbb{R}\times\mathbb{X},\mathbb{X})$.
\end{definition}

\begin{definition}[\cite{XT24}] \rm
A continuous function $f(t,x):\mathbb{R}\times\mathbb{R}\to\mathbb{X}$
is called bi-almost automorphic if for every sequence of real numbers
$\{s_n'\}_{n\in \mathbb{N}}$, there exists a subsequence
$\{s_n\}_{n\in \mathbb{N}}$ such that
\begin{equation*}
g(t,s):=\lim_{n\to\infty}f(t+s_n,s+s_n)
\end{equation*}
is well-defined for each $t,s\in \mathbb{R}$, and
\begin{equation*}
\lim_{n\to\infty}g(t-s_n,s-s_n)=f(t,s)
\end{equation*}
for each $t,s\in \mathbb{R}$. The collection of all functions will be denoted
by $bAA(\mathbb{R}\times\mathbb{R},\mathbb{X})$.
\end{definition}


Let $\mathbb{U}$ denote the set of all functions
$\rho:\mathbb{R}\to(0,\infty)$, which are locally integrable
over $\mathbb{R}$ such that $\rho>0$ almost everywhere. For a given
$T>0$ and for each $\rho\in\mathbb{U}$, we set
$m(T,\rho):=\int_{-T}^{T}\rho(t)dt$.

Thus the space of weights $\mathbb{U}_{\infty}$ is defined by
\begin{equation*}
\mathbb{U}_{\infty}:=\{\rho\in\mathbb{U}:\lim_{T\to\infty}m(T,\rho)=\infty\}.
\end{equation*}

For a given $\rho\in\mathbb{U}_{\infty}$, we define
\begin{gather*}
PAA_0(\mathbb{X},\rho):=\big\{f\in
BC(\mathbb{R},\mathbb{X}):\lim_{T\to\infty}\frac{1}{m(T,\rho)}
\int_{-T}^{T}\|f(t)\|\rho(t)dt=0\Big\};
\\
\begin{aligned}
PAA_0(\mathbb{Y},\mathbb{X},\rho)
:=\Big\{&f\in C(\mathbb{R}\times\mathbb{Y},\mathbb{X}):f(\cdot,y)
 \text{ is bounded for each $y\in\mathbb{Y}$ and }\\
&\lim_{T\to\infty}\frac{1}{m(T,\rho)}\int_{-T}^{T}\|f(t,y)\|\rho(t)dt=0
\text{ uniformly for } y\in\mathbb{Y}\Big\}.
\end{aligned}
\end{gather*}
To study the delay case, we introduce spaces of functions defined for each $r>0$ by
\begin{gather*}
\mathcal{W}(T,f,r,\rho)=\frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\|f(\theta)\|\Big)\rho(t) dt\,,
\\
PAA_0(\mathbb{X}, r, \rho):=\big\{f\in
BC(\mathbb{R},\mathbb{X}):\lim_{T\to\infty}\frac{1}{m(T,\rho)}
\int_{-T}^{T}\Big(\sup_{\theta\in[t-r,t]}\|f(\theta)\|\Big)\rho(t)dt=0\Big\}, \\
\begin{aligned}
&PAA_0(\mathbb{Y},\mathbb{X}, r, \rho)\\
&:= \Big\{f\in C(\mathbb{R}\times\mathbb{Y},\mathbb{X}):
f(\cdot,y)\text{ is bounded for each $y\in\mathbb{Y}$ and } \\
&\quad \lim_{T\to\infty}\frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\|f(\theta,y)\|\Big)\rho(t)dt=0
\text{ uniformly for } y\in\mathbb{Y}\Big\}.
\end{aligned}
\end{gather*}

\begin{definition}[\cite{BJ4}] \rm
Let $\rho\in\mathbb{U}_{\infty}$. A function
$f\in BC(\mathbb{R},\mathbb{X})$ (respectively,
$f\in BC(\mathbb{R}\times\mathbb{Y},\mathbb{X}))$ is called weighted pseudo almost
automorphic if it can be expressed as $f=g+\phi$, where
$g\in AA(\mathbb{X})$ (respectively, $AA(\mathbb{R}\times\mathbb{Y},\mathbb{X}))$
and $\phi\in PAA_0(\mathbb{X},\rho)$ (respectively,
$PAA_0(\mathbb{Y},\mathbb{X},\rho)$). We denote by $WPAA(\mathbb{X})$
(respectively, $WPAA(\mathbb{R}\times\mathbb{Y},\mathbb{X})$) the set
of all such functions.
\end{definition}

\begin{definition}[\cite{ZR22}] \rm
 Let $\rho\in\mathbb{U}_{\infty}$. A function
$f\in BC(\mathbb{R},\mathbb{X})$ (respectively,
$f\in BC(\mathbb{R}\times\mathbb{Y},\mathbb{X}))$ is called weighted pseudo almost
automorphic of class $r$ if it can be expressed as $f=g+\phi$, where $g\in
AA(\mathbb{X})$ (respectively, $AA(\mathbb{R}\times\mathbb{Y}, \mathbb{X}))$
 and $\phi\in PAA_0(\mathbb{X}, r, \rho)$ (respectively,
$PAA_0(\mathbb{Y},\mathbb{X}, r, \rho)$). We denote by $WPAA(\mathbb{X}, r)$
(respectively, $WPAA(\mathbb{R}\times\mathbb{Y},\mathbb{X}, r)$)
the set of all such functions.
\end{definition}

\begin{definition}[\cite{DT11,NG17}] \rm
The Bochner transform $f^b(t,s), t\in\mathbb{R},s\in[0,1]$, of a function
$f:\mathbb{R}\to\mathbb{X}$ is defined by
\begin{equation*}
f^b(t,s):=f(t+s).
\end{equation*}
\end{definition}

\begin{remark}[\cite{DT11}] \rm
(i) A function
$\varphi(t,s), t\in\mathbb{R}, s\in[0,1]$, is the Bochner transform of
a certain function $f$, $\varphi(t,s)=f^b(t,s)$, if and only if
$\varphi(t+\tau,s-\tau)=\varphi(s,t)$ for all
$t\in\mathbb{R},s\in[0,1]$ and $\tau\in [s-1,s]$.

(ii) Note that if $f=h+\varphi$, then $f^b=h^b+\varphi^b$.
Moreover, $(\lambda f)^b=\lambda f^b$ for each scalar $\lambda$.
\end{remark}

\begin{definition}[\cite{DT11}] \rm
The Bochner transform $f^b(t,s,u), t\in\mathbb{R}, s\in[0,1]$,
$u\in\mathbb{X}$ of a function
$f:\mathbb{R}\times\mathbb{X}\to\mathbb{X}$ is defined by
\begin{equation*}
f^b(t,s,u):=f(t+s,u)\quad \text{for each } u\in\mathbb{X}.
\end{equation*}
\end{definition}

We always denote by $\|\cdot\|_p$ the norm of space $L^p(0,1;\mathbb{X})$
for  $p\in[1,\infty)$.

\begin{definition}[\cite{LH14,NG17}] \rm
Let $p\in[1,\infty)$. The space $BS^p(\mathbb{X})$
of all Stepanov bounded functions, with the exponent $p$, consists
of all measurable functions $f:\mathbb{R}\to\mathbb{X}$ such
that $f^b\in L^{\infty}\left(\mathbb{R},L^p(0,1;\mathbb{X})\right)$. This is
a Banach space with the norm
\begin{equation*}
\|f\|_{S^p}=\|f^b\|_{L^{\infty}(\mathbb{R},L^p)}
=\sup_{t\in\mathbb{R}}\Big(\int_{t}^{t+1}\|f(\tau)\|^pd\tau\Big)^{1/p}
=\sup_{t\in\mathbb{R}}\|f(t+\cdot)\|_p.
\end{equation*}
\end{definition}


\begin{lemma}[\cite{ZR22}] \label{lem2.8}
Let $\rho\in\mathbb{U}_{\infty}$. Suppose that $PAA_0(\mathbb{X}, r, \rho)$
is translation invariant. Then the decomposition of weighted pseudo almost
 automorphic functions of class $r$ is unique.
\end{lemma}

\begin{lemma}[\cite{ZR22}]\label{lem2.9}
 Let $\rho\in\mathbb{U}_{\infty}$ and $PAA_0(\mathbb{X}, r, \rho)$
be translation invariant, then $WPAA(\mathbb{X}, r)$ is a Banach space with
norm $\|\cdot\|_{\infty}$.
\end{lemma}

\begin{definition}[\cite{LH14,NG17}] \rm
The space $AS^p(\mathbb{X})$ of Stepanov-like almost automorphic
(or $S^p$-almost automorphic) functions consists of all
$f\in BS^p(\mathbb{X})$ such that $f^b\in AA\left(L^p(0,1;\mathbb{X})\right)$.
In other words, a function $f\in L_{\rm loc}^p(\mathbb{R},\mathbb{X})$ is said
to be $S^p$-almost automorphic if its Bochner transform
$f^b:\mathbb{R}\to L^p(0,1;\mathbb{X})$ is almost automorphic in the
sense that for every sequence of real numbers
$\{s_n'\}_{n\in\mathbb{N}}$, there exist a subsequence
$\{s_n\}_{n\in\mathbb{N}}$ and a function
$g\in L_{\rm loc}^p(\mathbb{R},\mathbb{X})$ such that
\begin{gather*}
\lim_{n\to\infty}\Big(\int_{t}^{t+1}\|f(s+s_n)-g(s)\|^pds\Big)^{1/p}=0, \\
\lim_{n\to\infty}\left(\int_{t}^{t+1}\|g(s-s_n)-f(s)\|^pds\right)^{1/p}=0.
\end{gather*}
pointwise on $\mathbb{R}$.
\end{definition}

\begin{definition}[\cite{LH14,NG17}] \rm
 A function $f:\mathbb{R}\times\mathbb{Y}\to\mathbb{X}$, $(t,u)\to f(t,u)$
with $f(\cdot,u)\in L_{\rm loc}^p(\mathbb{R},\mathbb{X})$ for each
 $u\in\mathbb{Y}$, is said to be $S^p$-almost automorphic in
$t\in\mathbb{R}$ uniformly in $u\in\mathbb{Y}$ if $t\to f(t,u)$ is
$S^p$-almost automorphic for each $u\in\mathbb{Y}$.
That means, for every sequence of real numbers
$\{s_n'\}_{n\in\mathbb{N}}$, there exist a subsequence
$\{s_n\}_{n\in\mathbb{N}}$ and a function
$g(\cdot,u)\in L_{\rm loc}^p(\mathbb{R},\mathbb{X})$ such that
\begin{gather*}
\lim_{n\to\infty}\Big(\int_{t}^{t+1}\|f(s+s_n,u)-g(s,u)\|^pds\Big)^{1/p}=0,\\
\lim_{n\to\infty}\left(\int_{t}^{t+1}\|g(s-s_n,u)-f(s,u)\|^pds\right)^{1/p}=0,
\end{gather*}
pointwise on $\mathbb{R}$ and for each $u\in\mathbb{Y}$.
We denote by $AS^p(\mathbb{R}\times\mathbb{Y},\mathbb{X})$ the set of all
such functions.
\end{definition}

\begin{definition}[\cite{ZR20}] \rm
Let $\rho\in\mathbb{U}_{\infty}$. A function $f\in
BS^p(\mathbb{X})$ is said to be Stepanov-like weighted pseudo
almost automorphic (or $S^p$-weighted pseudo almost automorphic) if it
can be expressed as $f=g+\phi$, where $g\in
AS^p(\mathbb{X})$ and $\phi^b\in
PAA_0\left(L^p(0,1;\mathbb{X}),\rho\right)$. In other words, a
function $f\in L_{\rm loc}^p(\mathbb{R},\mathbb{X})$ is said to be
Stepanov-like weighted pseudo almost automorphic relatively to the
weight $\rho\in\mathbb{U}_{\infty}$, if its Bochner transform
$f^b:\mathbb{R}\to L^p(0,1;\mathbb{X})$ is weighted
pseudo almost automorphic in the sense that there exist two functions
$g,\phi:\mathbb{R}\to\mathbb{X}$ such that $f=g+\phi$,
where $g\in
AS^p(\mathbb{X})$ and
$\phi^b\in
PAA_0\left(L^p(0,1;\mathbb{X}),\rho\right)$.
 We denote by $WPAAS^p(\mathbb{X})$ the set of all such functions.
\end{definition}

\begin{definition}[\cite{ZR20}] \rm
Let $\rho\in\mathbb{U}_{\infty}$. A function
$f:\mathbb{R}\times\mathbb{Y}\to\mathbb{X}$,
$(t,u)\to f(t,u)$ with $f(\cdot,u)\in
L_{\rm loc}^p(\mathbb{R},\mathbb{X})$ for each $u\in\mathbb{Y}$, is
said to be Stepanov-like weighted pseudo almost automorphic (or
$S^p$-weighted pseudo almost automorphic) if it can be expressed as
$f=g+\phi$, where $g\in
AS^p(\mathbb{R}\times\mathbb{Y},\mathbb{X})$
and $\phi^b\in
PAA_0\left(\mathbb{Y},L^p(0,1;\mathbb{X}),\rho\right)$. We
denote by $WPAAS^p(\mathbb{R}\times\mathbb{Y},\mathbb{X})$ the
set of all such functions.
\end{definition}

\begin{definition}[\cite{ZR22}] \rm
Let $\rho\in\mathbb{U}_{\infty}$. A function $f\in
BS^p(\mathbb{X})$ is said to be Stepanov-like weighted pseudo
almost automorphic of class $r$ (or $S^p$-weighted pseudo almost automorphic of class $r$) if it
can be expressed as $f=g+\phi$, where $g\in
AS^p(\mathbb{X})$ and $\phi^b\in
PAA_0\left(L^p(0,1;\mathbb{X}), r, \rho\right)$. In other words, a
function $f\in L_{\rm loc}^p(\mathbb{R},\mathbb{X}, r)$ is said to be
Stepanov-like weighted pseudo almost automorphic of class $r$ relatively to the
weight $\rho\in\mathbb{U}_{\infty}$, if its Bochner transform
$f^b:\mathbb{R}\to L^p(0,1;\mathbb{X})$ is weighted
pseudo almost automorphic of class $r$ in the sense that there exist two functions
$g,\phi:\mathbb{R}\to\mathbb{X}$ such that $f=g+\phi$,
where $g\in AS^p(\mathbb{X})$ and
$\phi^b\in PAA_0\left(L^p(0,1;\mathbb{X}), r, \rho\right)$.
 We denote by $WPAAS^p(\mathbb{X}, r)$ the set of all such functions.
\end{definition}

\begin{definition}[\cite{ZR22}] \rm
Let $\rho\in\mathbb{U}_{\infty}$. A function
$f:\mathbb{R}\times\mathbb{Y}\to\mathbb{X}$,
$(t,u)\to f(t,u)$ with $f(\cdot,u)\in
L_{\rm loc}^p(\mathbb{R},\mathbb{X})$ for each $u\in\mathbb{Y}$, is
said to be Stepanov-like weighted pseudo almost automorphic of class $r$ (or
$S^p$-weighted pseudo almost automorphic of class $r$) if it can be expressed as
$f=g+\phi$, where $g\in
AS^p(\mathbb{R}\times\mathbb{Y},\mathbb{X})$
and $\phi^b\in PAA_0\left(\mathbb{Y},L^p(0,1;\mathbb{X}), r, \rho\right)$. We
denote by $WPAAS^p(\mathbb{R}\times\mathbb{Y},\mathbb{X}, r)$ the
set of all such functions.
\end{definition}

\begin{lemma}[\cite{ZR22}]\label{lem2.16} \label{le5}
Let $\rho\in\mathbb{U}_{\infty}$. The space $WPAAS^p(\mathbb{X}, r)$
equipped with the norm $\|\cdot\|_{S^p}$ is a Banach space.
\end{lemma}

Concerning infinite delays, we introduce the following  spaces of
functions as in \cite{ZR22}:
\begin{gather*}
PAA_0(\mathbb{X}, \infty, \rho):= \cap_{r>0}PAA_0(\mathbb{X}, r, \rho),\\
PAA_0(\mathbb{X}, \mathbb{Y}, \infty, \rho)
:= \cap_{r>0}PAA_0(\mathbb{X}, \mathbb{Y}, r, \rho),\\
PAA_0(L^p(0,1;\mathbb{X}), \infty, \rho)
:= \cap_{r>0}PAA_0(L^p(0,1;\mathbb{X}), r, \rho),\\
PAA_0(\mathbb{Y},L^p(0,1;\mathbb{X}), \infty, \rho)
:= \cap_{r>0}PAA_0(\mathbb{Y},L^p(0,1;\mathbb{X}), r, \rho).
\end{gather*}
Obviously, $PAA_0(\mathbb{X}, \infty, \rho)$ and
$PAA_0(\mathbb{X}, \mathbb{Y}, \infty, \rho)$ are, respectively, closed
subspaces of $PAA_0(\mathbb{X}, r, \rho)$ and
$PAA_0(\mathbb{X}, \mathbb{Y}, r, \rho)$, and hence both are Banach spaces.
By the same way, $PAA_0(L^p(0,1;\mathbb{X}), \infty, \rho)$ and
$PAA_0(\mathbb{Y},L^p(0,1;\mathbb{X}), \infty, \rho)$  are, respectively,
closed subspaces of
$PAA_0\left(L^p(0,1;\mathbb{X}), r, \rho\right)$ and
 $PAA_0(\mathbb{Y}, L^p(0,1;\mathbb{X}), r, \rho)$, and thus both are Banach spaces.

\begin{definition}[\cite{ZR22}] \rm
 Let $\rho\in\mathbb{U}_{\infty}$. A function
$f\in BC(\mathbb{R},\mathbb{X})$ (respectively,
$f\in BC(\mathbb{R}\times\mathbb{Y},\mathbb{X}))$ is called weighted pseudo almost
automorphic of class infinity if it can be expressed as $f=g+\phi$, where
$g\in AA(\mathbb{X})$ (respectively, $AA(\mathbb{R}\times\mathbb{Y}, \mathbb{X}))$
and $\phi\in PAA_0(\mathbb{X}, \infty, \rho)$ (respectively,
$PAA_0(\mathbb{Y},\mathbb{X}, \infty, \rho)$). We denote by
$WPAA(\mathbb{X}, \infty)$ (respectively,
$WPAA(\mathbb{R}\times\mathbb{Y},\mathbb{X}, \infty)$) the set of all such functions.
\end{definition}

\begin{definition}[\cite{ZR22}] \rm
Let $\rho\in\mathbb{U}_{\infty}$. A function $f\in BS^p(\mathbb{X})$
is said to be Stepanov-like weighted pseudo
almost automorphic of class infinity (or $S^p$-weighted pseudo
almost automorphic of class infinity) if it
can be expressed as $f=g+\phi$, where $g\in AS^p(\mathbb{X})$ and
$\phi^b\in PAA_0\left(L^p(0,1;\mathbb{X}), \infty, \rho\right)$.
In other words, a function $f\in L_{\rm loc}^p(\mathbb{R},\mathbb{X})$
is said to be Stepanov-like weighted pseudo almost automorphic of class
infinity relatively to the weight $\rho\in\mathbb{U}_{\infty}$,
if its Bochner transform
$f^b:\mathbb{R}\to L^p(0,1;\mathbb{X})$ is weighted
pseudo almost automorphic of class infinity in the sense that there exist
two functions
$g,\phi:\mathbb{R}\to\mathbb{X}$ such that $f=g+\phi$,
where $g\in AS^p(\mathbb{X})$ and
$\phi^b\in PAA_0\left(L^p(0,1;\mathbb{X}), \infty, \rho\right)$.
We denote by $WPAAS^p(\mathbb{X}, \infty)$ the set of all such functions.
\end{definition}

\begin{definition}[\cite{ZR22}]\rm
Let $\rho\in\mathbb{U}_{\infty}$. A function
$f:\mathbb{R}\times\mathbb{Y}\to\mathbb{X}$,
$(t,u)\to f(t,u)$ with $f(\cdot,u)\in
L_{\rm loc}^p(\mathbb{R},\mathbb{X})$ for each $u\in\mathbb{Y}$, is
said to be Stepanov-like weighted pseudo almost automorphic of class infinity (or
$S^p$-weighted pseudo almost automorphic of class infinity) if it can be
expressed as $f=g+\phi$, where $g\in AS^p(\mathbb{R}\times\mathbb{Y},\mathbb{X})$
and $\phi^b\in PAA_0\left(\mathbb{Y},L^p(0,1;\mathbb{X}), \infty, \rho\right)$.
We denote by $WPAAS^p(\mathbb{R}\times\mathbb{Y},\mathbb{X}, \infty)$ the
set of all such functions.
\end{definition}

Using similar ideas to those in \cite[Lemma2.7]{CY7}, we can easily show the
following results.

\begin{lemma}\label{lem2.21}
(i) Assume  $PAA_0(L^p(0,1,\mathbb{X}),r,\rho)$ is translation invariant,
then the decomposition of an $S^p$-weighted pseudo almost automorphic function
of class $r$ is unique.

(ii) The space $WPAAS^p(\mathbb{X},r)$ equipped with $\|\cdot\|_{S^p}$
is a Banach space.

(iii) $WPAA(\mathbb{X},r)$ is continuously embedded in $WPAAS^p(\mathbb{X},r)$.
\end{lemma}

\begin{lemma}\label{lem2.22}
(i) Assume that $PAA_0(L^p(0,1,\mathbb{X}),\infty,\rho)$
is translation invariant, then the decomposition of an $S^p$-weighted pseudo
almost automorphic function of class infinity is unique.

(ii) The space $WPAAS^p(\mathbb{X},\infty)$ equipped with
$\|\cdot\|_{S^p}$ is a Banach space.

(iii) $WPAA(\mathbb{X},\infty)$ is continuously embedded in
$WPAAS^p(\mathbb{X},\infty)$.
\end{lemma}

In this work we  use an axiomatic definition of the phase space $\mathfrak{B}$,
which is similar to the one introduce in (\cite{HY13}).
$\mathfrak{B}$ is a vector space of functions mapping $(-\infty,0]$ into
 $\mathbb{X}$ endowed with a seminorm $\|\cdot\|_{\mathfrak{B}}$ such that
the next axioms hold by (\cite{ZR22}).
\begin{itemize}
\item[(A1)] If $x:(-\infty, \sigma+a)\mapsto \mathbb{X}$,
$a>0$, $\sigma\in\mathbb{R}$, is continuous on $[\sigma,\sigma+a)$ and
$x_{\sigma}\in\mathfrak{B}$,
then for every $t\in[\sigma,\sigma+a)$ the following hold:
\begin{itemize}
\item[(i)] $x_{t}$ is in $\mathfrak{B}$;

\item[(ii)] $\|x(t)\|\leq H\|x_{t}\|_{\mathfrak{B}}$;

\item[(iii)] $\|x_{t}\|_{\mathfrak{B}}
\leq \widetilde{K}(t-\sigma)\sup\{\|x(s)\|:\sigma\leq s\leq t\}
+ \widetilde{M}(t-\sigma)\|x_{\sigma}\|_{\mathfrak{B}}$,
where $H > 0$ is a constant;
$\widetilde{K}, \widetilde{M} : [0,\infty)\mapsto [1,\infty)$,
$\widetilde{K}$ is continuous, $\widetilde{M}$ is locally bounded and
$H,  \widetilde{K},  \widetilde{M}$ are independent of $x(\cdot)$.
\end{itemize}

\item[(A1')] For the function $x(\cdot)$ appearing in (A1), the function
$t\to x_{t}$ is continuous from $[\sigma,\sigma+a)$ into $\mathfrak{B}$.

\item[(A2)] The space $\mathfrak{B}$ is complete.

\item[(A3)] If $(\varphi^{n})_{n\in\mathbb{N}}$ is a bounded sequence in
$BC((-\infty,0],\mathbb{X})$ given by functions with compact support and
$\varphi^{n}\to\varphi$ in the compact-open topology, then
$\varphi\in\mathfrak{B}$ and $\|\varphi^{n}-\varphi\|_{\mathfrak{B}}\to 0$
as $n\to\infty$.
\end{itemize}

\begin{definition}\cite{HE12} \rm
Let $\mathfrak{B}_0=\{\varphi\in\mathfrak{B}:\varphi(0)=0\}$ and
$S(t):\mathfrak{B}\to\mathfrak{B}$ be the $C_0$-semigroup defined by
$S(t)\varphi(\theta)=\varphi(0)$ on $[-t,0]$ and
$S(t)\varphi(\theta)=\varphi(t+\theta)$ on $(-\infty,-t]$.
The phase space $\mathfrak{B}$ is called a fading memory space if
$\|S(t)\varphi\|_{\mathfrak{B}}\to 0$ as $t\to \infty$ for every
$\varphi\in\mathfrak{B}_0$. We said that $\mathfrak{B}$ is a uniform
fading memory space if $\|S(t)\|_{\mathfrak{L}(\mathfrak{B}_0)}\to 0$
as $t\to\infty$.
\end{definition}

\begin{remark}[\cite{HE12}] \label{rem2.24} \rm
In this article we assume $\varsigma > 0$ and
$\|\varphi\|_{\mathfrak{B}}\leq\varsigma\sup_{\theta\leq 0}\|\varphi$ $(\theta)\|$
for each $\varphi\in\mathfrak{B}\cap BC((-\infty,0],\mathbb{X})$, see
\cite{HY13} for details. Moreover, if $\mathfrak{B}$ is a fading memory,
we assume that $\max\{\widetilde{K}(t),\widetilde{M}(t)\}\leq\Re$ for all
$t\geq0$, see\cite{HY13}.
\end{remark}

\begin{lemma}[\cite{HY13}] \label{lem2.25} 
The phase $\mathfrak{B}$ is a uniform fading memory space if, and only if,
axiom {\rm (A3)} holds, the function $\widetilde{K}$ is bounded and
$\lim_{t\to\infty}\widetilde{M}(t)=0$.
\end{lemma}

\section{Results on composition theorems}

The  aim of this section is to establish some new results on composition
 of Stepanov-like weighted pseudo almost automorphic functions of class
infinity. We first list the following ``uniform continuity condition"
with respect to the $L^p$-norm for a function
$h:\mathbb{R}\times\mathbb{X}\to\mathbb{X}$ with
$h(\cdot,u)\in L^p_{Loc}(\mathbb{R},\mathbb{X})$ for each $u\in \mathbb{X}$,
which was initially adopted in \cite{CY7}:
\begin{itemize}
\item[(A4)]
For any $\varepsilon>0$, there exists $\sigma>0$ such that
$x,y\in L^p(0,1,\mathbb{X})$ and $\|x-y\|_p<\sigma$ imply that
\[
\|h(t+\cdot,x(\cdot))-h(t+\cdot,y(\cdot))\|_p<\varepsilon, \quad t\in \mathbb{R}.
\]
\end{itemize}
In the sequel, we say that a function $\psi$ satisfies (A4) if
$\psi$ replaces $h$ in (A4).

Let $f\in AS^p(\mathbb{R}\times \mathbb{X},\mathbb{X})$, then for a
sequence $\{s_n\}\subset\mathbb{R}$, there exist a subsequence $\{\tau_n\}$
and a function $g:\mathbb{R}\times \mathbb{X}\to\mathbb{X}$ with
$g(\cdot,x)\in L_{\rm loc}^p(\mathbb{R},\mathbb{X})$, $x\in \mathbb{X}$
such that for each $t\in \mathbb{R}$,
\begin{equation*}
\lim_{n\to\infty}\|f(t+\tau_n+\cdot,x)-g(t+\cdot,x)\|_p
=\lim_{n\to\infty}\|g(t-\tau_n+\cdot,x)-f(t+\cdot,x)\|_p=0.
\end{equation*}
\begin{itemize}

\item[(A5)] $f\in AS^p(\mathbb{R}\times \mathbb{X},\mathbb{X})$ satisfies (A4),
and for a sequence $\{s_n\}\subset\mathbb{R}$, there exist a subsequence
$\{\tau_n\}$ and a function $g$ given above such that $g$ satisfies (A4).
\end{itemize}


\begin{lemma}[\cite{CY7}] \label{lem3.1}
Let $h$ be the function in {\rm (A4)}, and $x$: $\mathbb{R}\to\mathbb{X}$ with
$\overline{x(\mathbb{R})}$ compact. For $\varepsilon>0$, there exist a finite
set $\{x_{k}\}_{k=1}^{m}\subset\overline{x(\mathbb{R})}$ such that
\[
\|h(t+\cdot,x(t+\cdot))\|_p<\varepsilon+m\sup_{1\leq k\leq m}\|h(t+\cdot, x_{k})\|_p,
\quad t\in \mathbb{R}.
\]
\end{lemma}

\begin{lemma}[\cite{ZR22}] \label{lem3.2}
Let $\rho\in U_{\infty}$ and $f\in BS^p(\mathbb{X})$, then
$f^b\in PAA_0(L^p(0,1,\mathbb{X}),r,\rho)$ if and only if for any
$\varepsilon>0$,
\begin{equation*}
\lim_{T\to\infty}\frac{1}{m(T,\rho)}\int_{M_{T,\varepsilon(f)}}\rho(t)dt=0,
\end{equation*}
where
\[
M_{T,\varepsilon(f)}=\big\{t\in[-T,T]:\sup_{\theta\in [t-r,t]}
\Big(\int_{\theta}^{\theta+1}\|f(s)\|^pds\Big)^{1/p}\geq\varepsilon\big\}.
\]
\end{lemma}

\begin{lemma}[\cite{CY7}] \label{lem3.3}
Assume that $f$ satisfies {\rm (A5)} and $x\in AS^p(\mathbb{X})$ with
$\overline{x}(\mathbb{R})$ compact. Then $f(\cdot,x(\cdot))\in AS^p(\mathbb{X})$.
\end{lemma}

Next, we give results in the compositions of $S^p$-weighted pseudo
almost automorphic functions of class $r$.

\begin{theorem} \label{thm3.4}
Let $\rho\in U_{\infty}$,
$f=g+\phi\in WPAAS^p(\mathbb{R}\times\mathbb{X},\mathbb{X},r)$,
$u=u_1+u_2\in WPAAS^p(\mathbb{X},r)$,
$g\in AS^p(\mathbb{R}\times\mathbb{X},\mathbb{X})$,
$\phi^b\in PAA_0(\mathbb{X},L^p(0,1,\mathbb{X}),r,\rho)$,
$u_1\in AS^p(\mathbb{X}), u_2^b\in PAA_0(L^p(0,1,\mathbb{X}),r,\rho)$,
$Q=\overline{\{u_1(t):t\in \mathbb{R}\}}$ compact and there exist a continuous
function $\mathfrak{L}_{f}(\cdot):\mathbb{R}\to [0,\infty)$ satisfying 
\begin{equation}
\Big(\int_{t}^{t+1}\|f(s,x_1)-f(s,x_2)\|^pds\Big)^{1/p}
\leq \mathfrak{L}_{f}(t)\|x_1-x_2\|. \label{a3.1}
\end{equation}
If $\xi^b\in PAA_0(\mathbb{R},L^p(0,1,\mathbb{X}),\rho)$, then
\begin{gather}
\lim_{T\to\infty}\sup\frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\mathfrak{L}_{f}(\theta+\cdot)\Big)\rho(t)dt
<\infty, \quad \label{a3.2}
\\
\lim_{T\to\infty}\frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\mathfrak{L}_{f}(\theta+\cdot)\Big)
\xi(t)\rho(t)dt<\infty\,. \label{a3.3}
\end{gather}
If
\begin{itemize}
\item[(i)] $g(t,x)$ satisfies {\rm (A5)} and
\item[(ii)] $\phi$ satisfies (A4),
\end{itemize}
Then $f(\cdot,u(\cdot))\in WPAAS^p(\mathbb{X},r)$.
\end{theorem}

\begin{proof}
Let $G(t)=g\left(t,u_1(t)\right)$,
$H(t)=f\left(t,u(t)\right)-f\left(t,u_1(t)\right)$,
$\Lambda(t)=\phi\left(t,u_1(t)\right)$, $t\in \mathbb{R}$. Then
\begin{equation*}
f(t,u(t))=g\left(t,u_1(t)\right)+f\left(t,u(t)\right)
-f\left(t,u_1(t)\right)+\phi\left(t,u_1(t\right))=G(t)+H(t)+\Lambda(t).
\end{equation*}
We have $G(t)\in AS^p(\mathbb{X})$ by Lemma \ref{lem3.3}, then
it remains to show that $H^b,\Lambda^b$ is in $PAA_0(L^p(0,1,\mathbb{X}),r,\rho)$.

Indeed, for $T>0$, using \eqref{a3.1}, we see that
\begin{align*}
&\frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\Big(\int_{\theta}^{\theta+1}\|H(s)\|^pds\Big)^{1/p}
 \Big)\rho(t)dt\\
&= \frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\Big(\int_{\theta}^{\theta+1}\|f(t,u(t))-f(t.u_1(t))
 \|^pds\Big)^{1/p}\Big)\rho(t)dt\\
&\leq \frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\mathfrak{L}_{f}(\theta)\|u_2(\theta)\|\Big)\rho(t)dt\\
&\leq \frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\mathfrak{L}_{f}(\theta)\Big)
\Big(\sup_{\theta\in[t-r,t]}\Big(\int_{\theta}^{\theta+1}\|u_2(s)\|^pds\Big)^{1/p}
 \Big)\rho(t)dt\\
&=\frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\mathfrak{L}_{f}(\theta)\Big)
 \Big(\sup_{\theta\in[t-r,t]}u_2(\theta+\cdot)\Big)\rho(t)dt.
\end{align*}
This implies that $H^b(t)\in PAA_0(L^p(0,1,\mathbb{X}),r,\rho)$ by \eqref{a3.3}.

Next, we prove $\Lambda^b\in PAA_0(L^p(0,1,\mathbb{X}),r,\rho)$.
For $\varepsilon>0$, let $\sigma$ be given by (A4) with $\phi$ in the place
of $h$, by Lemma \ref{lem3.1}, there is a finite set
$\{x_{k}\}_{k=1}^{m}\subset \overline{\{u_1(t),t\in \mathbb{R}\}}$
such that for $t\in \mathbb{R}$,
\begin{equation*}
\|\phi(t+\cdot,u_1(t+\cdot))\|_p
<\varepsilon+m\sup_{1\leq k\leq m}\|\phi(t+\cdot,x_{k})\|_p.
\end{equation*}
Since $\phi^b\in PAA_0(\mathbb{X},L^p(0,1,\mathbb{X}),r,\rho)$, for each
$x\in \mathbb{X}$, there is $T>T_0$, $1\leq k\leq m$,
\begin{equation*}
\mathcal{W}(T,\phi^b(\cdot,x_{k}),r,\rho)
=\frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\|\phi(\theta+\cdot,x_{k})\|_p\Big)\rho(t)dt
<\frac{\varepsilon}{m}.
\end{equation*}
Then for $T>T_0$,
\begin{align*}
\mathcal{W}(T,\Lambda^b,r,\rho)
&=\mathcal{W}(T,\Lambda^b(\cdot,u_1(\cdot)),r,\rho)\\
&=\frac{1}{m(T,\rho)}\int_{-T}^{T}
 \Big(\sup_{\theta\in[t-r,t]}\|\phi(\theta+\cdot,u_1(t+\cdot))\|_p\Big)\rho(t)dt\\
&\leq \varepsilon+m\sup_{1\leq k\leq m}\frac{1}{m(T,\rho)}
 \int_{-T}^{T}\Big(\sup_{\theta\in[t-r,t]}\|\phi(\theta+\cdot,x_{k})\|_p\Big)
 \rho(t)dt\\
&=\varepsilon+m\mathcal{W}(T,\phi^b(\cdot,x_{k}),r,\rho)\\
&=\varepsilon+m\frac{\varepsilon}{m}
=2\varepsilon.
\end{align*}
This yields  $\lim_{T\to\infty}\mathcal{W}(T,\Lambda^b,r,\rho)=0$.
That is $\Lambda^b\in PAA_0(L^p(0,1,\mathbb{X}),r,\rho)$. The proof is complete.
\end{proof}

\begin{theorem} \label{thm3.5}\rm
Let $\rho\in U_{\infty}$,
$F=F_1+F_2\in WPAAS^p(\mathbb{R}\times\mathbb{X},\mathbb{X},r)$,
$\phi=\phi_1+\phi_2\in WPAAS^p(\mathbb{X},r)$ with
$Q=\overline{\{\phi_1(t):t\in \mathbb{R}\}}$ compact,
$F_1\in AS^p(\mathbb{R}\times\mathbb{X},\mathbb{X})$,
$F_2^b\in PAA_0\left(\mathbb{X},L^p(0,1,\mathbb{X}),r,\rho\right)$,
$\phi_1\in AS^p(\mathbb{X})$, $\phi_2^b\in PAA_0(L^p(0,1,\mathbb{X}),r,\rho)$.
Assume that $F_1$ satisfies {\rm (A5)}, $F_2$ satisfies {\rm (A4)} and
$\{F(\cdot,z):z\in \mathbb{J}\}$ is bounded in $WPAAS^p(\mathbb{X},r)$
for any bounded $\mathbb{J}\subset \mathbb{X}$, then
$t\to F(t,\phi(\cdot))\in WPAAS^p(\mathbb{X},r)$.
\end{theorem}

\begin{proof}
Let $\Upsilon(t)=F_1\left(t,\phi_1(t)\right)$,
$\Psi(t)=F\left(t,\phi(t)\right)-F\left(t,\phi_1(t)\right)$,
$\Phi(t)=F_2\left(t,\phi_1(t)\right)$, $t\in \mathbb{R}$. Then
\begin{equation*}
F(t,\phi(t))=F_1\left(t,\phi_1(t)\right)+F\left(t,\phi(t)\right)
-F\left(t,\phi_1(t)\right)+F_2\left(t,\phi_1(t)\right)
=\Upsilon(t)+\Psi(t)+\Phi(t).
\end{equation*}
We have $\Upsilon(t)\in AS^p(\mathbb{X})$ by Lemma \ref{lem3.3},
so we need only to prove $\Psi^b,\Phi^b\in PAA_0(L^p$ $(0,1,\mathbb{X}),r,\rho)$.

It is easy to see that $\Psi\in BS^p(\mathbb{X})$ since $\phi$ and $\phi_1$
are bounded and $\{F(\cdot,z):z\in \mathbb{J}\}$ is bounded in
$WPAAS^p(\mathbb{X},r)$ for any bounded $\mathbb{J}\subset \mathbb{X}$.
Noticing that $F$ satisfies (A4) since $F_1$ and $F_2$ satisfies (A4),
for $\varepsilon>0$, let $\sigma>0$ be given by (A4), then
\[
\|\Psi(t+\cdot)\|_p=\|F(t+\cdot,\phi(t+\cdot))-F(t+\cdot,\phi_1(t+\cdot))\|_p
<\varepsilon,
\]
 for $\|\phi_2(t+\cdot)\|_p<\sigma$,
where $\phi_2(s)=\phi(s)-\phi_1(s)$.
Hence, for each $t\in \mathbb{R}$, $\|\phi_2(s)\|<\sigma$, $s\in[t,t+1]$
implies that
\begin{align*}
\Big(\int_{t}^{t+1}\|\Psi(s)\|^pds\Big)^{1/p}
&=\Big(\int_{t}^{t+1}\|F(s,\phi(s))-F(s,\phi_1(s))\|^pds\Big)^{1/p}\\
&=\|F(t+\cdot,\phi(t+\cdot))-F(t+\cdot,\phi_1(t+\cdot))\|_p
<\varepsilon.
\end{align*}
We can obtain
\begin{align*}
&\sup_{\theta\in[t-r,t]}\Big(\int_{\theta}^{\theta+1}\|\Psi(s)\|^pds\Big)^{1/p}\\
&=\sup_{\theta\in[t-r,t]}\Big(\int_{\theta}^{\theta+1}\|F(s,\phi(s))
-F(s,\phi_1(s))\|^pds\Big)^{1/p}
<\varepsilon.
\end{align*}
Let
\begin{equation*}
M_{T,\sigma(\phi_2)}=\Big\{t\in[-T,T]:
\sup_{\theta\in[t-r,t]}\Big(\int_{\theta}^{\theta+1}\|\phi_2(s)\|^pds\Big)^{1/p}
\geq\sigma\Big\}.
\end{equation*}
So we obtain
\begin{equation*}
M_{T,\varepsilon(\phi_2)}
=M_{T,\varepsilon(F(\cdot,\phi(\cdot))-F(\cdot,\phi_1(\cdot)))}
\subseteq M_{T,\sigma(\phi_2)}.
\end{equation*}
Since $\phi_2^b\in PAA_0(L^p(0,1,\mathbb{X}),r,\rho)$ by Lemma \ref{lem3.2},
we obtain
\begin{equation*}
\lim_{T\to\infty}\int_{M_{T,\sigma(\phi_2)}}\rho(t)dt=0.
\end{equation*}
Thus
\begin{equation*}
\lim_{T\to\infty}\int_{M_{T,\varepsilon(\Psi)}}\rho(t)dt=0.
\end{equation*}
This shows that $\Psi^b\in PAA_0(L^p(0,1,\mathbb{X}),r,\rho)$.

For $\varepsilon>0$, let $\sigma$ be given by (A4) with $F_2$ in the place of
$h$, by Lemma \ref{lem3.1}, there is a finite set
$\{x_{k}\}_{k=1}^{m}\subset\overline{\{\phi_1(t):t\in \mathbb{R}\}}$
such that for $t\in \mathbb{R}$
\begin{equation*}
\|F_2(t+\cdot,\phi_1(t+\cdot))\|_p
<\varepsilon+m\sup_{1\leq k\leq m}\|F_2(t+\cdot,x_{k})\|_p.
\end{equation*}
Since $F_2^b\in PAA_0(\mathbb{X},L^p(0,1,\mathbb{X}),r,\rho)$ for each
$x\in\mathbb{X}$, there is $T>T_0$, $1\leq k\leq m$,
\begin{equation*}
\mathcal{W}(T,F_2^b(\cdot,x_{k}),r,\rho)
=\frac{1}{m(T,\rho)}\int_{-T}^{T}\Big(\sup_{\theta\in[t-r,t]}
\|F_2(\theta+\cdot,x_{k})\|_p\Big)\rho(t)dt<\frac{\varepsilon}{m}.
\end{equation*}
Then for $T>T_0$,
\begin{align*}
\mathcal{W}(T,\Phi^b,r,\rho)
&=\mathcal{W}(T,F_2^b(\cdot,\phi_1(\cdot)),r,\rho)\\
&=\frac{1}{m(T,\rho)}\int_{-T}^{T}
 \Big(\sup_{\theta\in[t-r,t]}\|F_2(\theta+\cdot,\phi_1(t+\cdot))\|_p\Big)\rho(t)dt\\
&\leq \varepsilon+m\sup_{1\leq k\leq m}\frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\|\phi(\theta+\cdot,x_{k})\|_p\Big)\rho(t)dt\\
&=\varepsilon+m\mathcal{W}(T,F_2^b(\cdot,x_{k}),r,\rho)\\
&=\varepsilon+m\frac{\varepsilon}{m}
=2\varepsilon.
\end{align*}
This implies $\lim_{T\to\infty}\mathcal{W}(T,\Phi^b,r,\rho)=0$.
That is $\Phi^b\in PAA_0(L^p(0,1,\mathbb{X}),r,\rho)$. The proof is complete.
\end{proof}

\begin{lemma}[\cite{ZR22}] \label{lem3.6}
Let $u\in WPAA(\mathbb{X},\infty)$ where $\rho\in\mathbb{U}_{\infty}$.
Assume that $\mathfrak{B}$ is a uniform fading memory space.
Then the function $t\to u_{t}$ belongs to $WPAA(\mathfrak{B},\infty)$.
\end{lemma}

\begin{lemma}[\cite{ZR22}] \label{lem3.7}
Let $\rho\in\mathbb{U}_{\infty}$, $u\in WPAAS^p(\mathbb{X},\infty)$ and
assume that $\mathfrak{B}$ is a uniform fading memory space.
Then the function $t\to u_{t}$ belongs to $WPAAS^p(\mathfrak{B},\infty)$.
\end{lemma}

One of the consequence of Lemma \ref{lem3.7} is the following modified
version of Theorems \ref{thm3.4} and \ref{thm3.5}.

\begin{corollary} \label{cor3.8}
Let $\rho\in U_{\infty}$,
$f\in WPAAS^p(\mathbb{R}\times \mathbb{X},\mathbb{X},\infty)$ and
$u\in WPAAS^p(\mathbb{X},\infty)$. Assume that the condition of (i) and (ii)
in the Theorem \ref{thm3.4} is satisfied and there exists a continuous
function $\mathfrak{L}(\cdot):\mathbb{R}\to[0,\infty)$, such that \eqref{a3.1} holds.
 If conditions \eqref{a3.2} and \eqref{a3.3} hold for every $r>0$, then the
function $f(t,u(t))\in WPAAS^p(\mathbb{X},\infty)$.
\end{corollary}

\begin{corollary} \label{cor3.9}
Let $\rho\in U_{\infty}$,
$F=F_1+F_2\in WPAAS^p(\mathbb{R}\times\mathbb{X},\mathbb{X},\infty)$,
$\phi=\phi_1+\phi_2\in WPAAS^p(\mathbb{X},\infty)$ with
$Q=\overline{\{\phi_1(t):t\in \mathbb{R}\}}$ compact,
$F_1\in AS^p(\mathbb{R}\times\mathbb{X},\mathbb{X})$,
$F_2^b\in PAA_0\left(\mathbb{X},L^p(0,1,\mathbb{X}),\infty,\rho\right)$,
$\phi_1\in AS^p(\mathbb{X})$, $\phi_2^b\in PAA_0(L^p(0,1,\mathbb{X}),\infty,\rho)$.
Assume that $F_1$ satisfies {\rm (A5)}, $F_2$ satisfies {\rm (A4)} and
$\{F(\cdot,z):z\in \mathbb{J}\}$ is bounded in $WPAAS^p(\mathbb{X},\infty)$
for any bounded $\mathbb{J}\subset \mathbb{X}$, then
$t\to F(t,\phi(\cdot))\in WPAAS^p(\mathbb{X},\infty)$.
\end{corollary}

By Lemma \ref{lem2.21} (iii) and Theorem \ref{thm3.5}, Lemma \ref{lem2.22} (iii)
and Corollary \ref{cor3.9}, we have the following corollaries:

\begin{corollary} \label{cor3.10}
Let $\rho\in U_{\infty}$, $F=F_1+F_2\in WPAAS^p(\mathbb{R}\times\mathbb{X},
\mathbb{X},r)$ and $\phi\in WPAA(\mathbb{X},r)$. Assume that $F_1$ satisfies
{\rm (A5)}, $F_2$ satisfies {\rm (A4)} and $\{F(\cdot,z):z\in \mathbb{J}\}$
is bounded in $WPAAS^p(\mathbb{X},r)$ for any bounded
$\mathbb{J}\subset \mathbb{X}$, then
$t\to F(t,\phi(\cdot))\in WPAAS^p(\mathbb{X},r)$.
\end{corollary}

\begin{corollary} \label{cor3.11}
Let $\rho\in U_{\infty}$,
$F=F_1+F_2\in WPAAS^p(\mathbb{R}\times\mathbb{X},\mathbb{X},\infty)$ and
$\phi\in WPAA(\mathbb{X},\infty)$. Assume that $F_1$ satisfies {\rm (A5)},
$F_2$ satisfies {\rm (A4)} and $\{F(\cdot,z):z\in \mathbb{J}\}$ is bounded
in $WPAAS^p(\mathbb{X},\infty)$ for any bounded $\mathbb{J}\subset \mathbb{X}$,
then $t\to F(t,\phi(\cdot))\in WPAAS^p(\mathbb{X},\infty)$.
\end{corollary}

\begin{corollary} [\cite{ZR22}] \label{cor3.12}
Let $\rho\in U_{\infty}$, $f\in WPAA(\mathbb{R}\times\mathbb{X},\mathbb{X},\infty)$
and $u\in WPAA(\mathbb{X}$, $\infty)$. Assume that the following conditions
 are satisfied
\begin{itemize}
\item[(i)] There exist a constant $L>0$ such that
$\|f(t,x)-f(t,y)\|\leq L\|x-y\|$ for all $x,y\in \mathbb{X}$ and $t\in \mathbb{R}$.

\item[(ii)] $g(t,x)$ is uniformly continuous in any bounded subset
$K'\subset \mathbb{X}$ uniformly for $t\in \mathbb{R}$.
\end{itemize}
Then the function $t\to f(t,u(t))$ belongs to $WPAA(\mathbb{X},\infty)$.
\end{corollary}

\section{Weighted pseudo almost automorphic mild solution}

In this section, we study weighted pseudo almost automorphic mild
solutions to the neutral equation \eqref{a1.1}.
 We list the following basic assumptions:
\begin{itemize}
\item[(A6)] The system
\begin{equation*}
u'(t)=A(t)u(t),\quad t\geq s,\quad u(s)=\phi\in \mathbb{X}.
\end{equation*}
has an associated evolution family of operators
$\{U(t,s):t\geq s\text{ with }t,s\in\mathbb{R}\}$.
Further, we assume that the domains of operators $A(t)$ are constant
in $t$, that is, $D(A(t))=D=\mathcal{Y}$ for all
$t\in \mathbb{R}$ and that the evolution family
$U(t,s)$ is asymptotically stable in the sense that there exist some
constants $M,\delta >0$ such that
\begin{equation*}
\|U(t,s)\|\leq Me^{-\delta(t-s)}
\end{equation*}
for all $t,s\in \mathbb{R}$ with $t\geq s$.

\item[(A7)] The function $s\to A(s)U(t,s)$ defined from
$(-\infty,t)$ into $\mathfrak{L}(\mathbb{R}\times\mathcal{Y})$ is strongly
measurable and there exist a nonincreasing function
$H:[0,\infty)\to [0,\infty)$ and $\delta>0$ with
$e^{-\delta s}H(s)\in L^{1}([0,\infty))$ such that
\begin{equation*}
\|A(s)U(t,s)\|_{\mathfrak{L}(\mathcal{Y},\mathbb{X})}
\leq e^{-\delta s}H(t-s),\quad t>s.
\end{equation*}
\item[(A8)]
$g\in WPAAS^p(\mathbb{R},\mathbb{X},\infty)$ and there exist a positive
constant $L_{g}$ such that for $\psi_{i}\in \mathfrak{B},i=1,2$,
$\|g(t,\psi_1)-g(t,\psi_2)\|_p\leq L_{g}\|\psi_1-\psi_2\|_{\mathfrak{B}}$.

\item[(A9)] $f\in WPAA(\mathbb{R},\mathbb{X},\infty)$ and there exist a
positive constant $L_{f}$ such that for $\psi_{i}\in \mathfrak{B}, i=1,2$,
 $\|f(t,\psi_1)-f(t,\psi_2)\|\leq L_{f}\|\psi_1-\psi_2\|_{\mathfrak{B}}$.

\item[(A10)] The series
\begin{equation*}
\sum_{k=1}^{\infty}\Big(\int_{t-k}^{t-k+1}e^{-\delta q(t-s)}H^{q}(t-s)ds
\Big)^{1/q}
\end{equation*}
converges, $q>1$, and let
$K=\Big(\int_{-\infty}^{t}e^{-\delta q(t-s)}H^{q}(t-s)ds\Big)^{1/q}$.

Let $q>1$ such that $\frac{1}{p}+\frac{1}{q}=1$. Denote
\begin{equation*}
\alpha_0=M\Big(\frac{e^{q\delta-1}}{q\delta}\Big)^{1/q},\quad
\alpha=\alpha_0\sum_{k=1}^{\infty}e^{-\delta k}.
\end{equation*}

\item[(A11)]
The function $\mathbb{R}\times\mathbb{R}\mapsto \mathbb{X}$,
$(t,s)\mapsto U(t,s)x\in  bAA(\mathbb{R}\times\mathbb{R},\mathcal{Y})$
uniformly for $x\in \mathbb{X}$.

\item[(A12)]
The function $\mathbb{R}\times\mathbb{R}\mapsto \mathbb{X}$,
$(t,s)\mapsto A(s)U(t,s)x\in  bAA(\mathbb{R}\times\mathbb{R},\mathbb{X})$
 uniformly for $x\in \mathcal{Y}$.
\end{itemize}

\begin{definition}[\cite{DT9}] \rm
A continuous function $u:[\sigma,\sigma+a)\to \mathbb{X},a>0$,
is a mild solution of neutral system \eqref{a1.1} on $[\sigma,\sigma+a)$,
if the function $s\to A(s)U(t,s)f(s,u_{s})$ is integrable on
$[\sigma,t)$ for every $\sigma<t<\sigma+a$, $u_{\sigma}=\varphi$, and
\begin{align*}
u(t)
&=U(t,\sigma)(\varphi(0)+f(\sigma,\varphi))-f(t,u_{t})
 -\int_{\sigma}^{t}A(s)U(t,s)f(s,u_{s})ds\\
&\quad +\int_{\sigma}^{t}U(t,s)g(s,u_{s})ds,\quad t\in[\sigma,\sigma+a).
\end{align*}
\end{definition}

Under assumptions (A6) and (A7), it can be easily shown that the function
\begin{equation*}
u(t)=-f(t,u_{t})+\int_{-\infty}^{t}U(t,s)g(s,u_{s})ds
-\int_{-\infty}^{t}A(s)U(t,s)f(s,u_{s})ds,
\end{equation*}
for each $t\in \mathbb{R}$ is a mild solution of \eqref{a1.1}.

\begin{lemma}[\cite{ZR22}] \label{lem4.2}
Assume that conditions {\rm (A6), (A7), (A11)} hold.
Let $\rho\in\mathbb{U}_{\infty}$ and $u\in WPAAS^p(\mathbb{X},\infty)$,
and
\begin{equation*}
v(t):=\int_{-\infty}^{t}U(t,s)u(s)ds, \quad t\in\mathbb{R}.
\end{equation*}
Then $v\in WPAA(\mathbb{X},\infty)$.
\end{lemma}

\begin{lemma}\label{lem4.3}
Assume that conditions {\rm (A6), (A7),  (A12)} hold.
Let $\rho\in\mathbb{U}_{\infty}$ and $u\in WPAAS^p(\mathbb{X},\infty)$,
and
\begin{equation*}
v(t):=\int_{-\infty}^{t}A(s)U(t,s)u(s)ds, \quad t\in\mathbb{R}.
\end{equation*}
Then $v\in WPAA(\mathbb{X},\infty)$.
\end{lemma}

\begin{proof}
Since $u\in WPAAS^p(\mathbb{X},\infty)$, there exist functions
$\overline{\psi}$ in $AS^p(\mathbb{X})$ and
$\overline{\omega}^b$ in $PAA_0(L^p(0,1;\mathbb{X}),\infty,\rho)$
such that $u=\overline{\psi}+\overline{\omega}$.
\[
v(t):=\int_{-\infty}^{t}A(s)U(t,s)\overline{\psi}(s)ds
+\int_{-\infty}^{t}A(s)U(t,s)\overline{\omega}(s)ds
=\overline{x}(t)+\overline{y}(t).
\]
To prove that $v$ is a weighted pseudo almost automorphic function of
class infinity, we only need to verify $\overline{x}(t)\in AA(\mathbb{X})$
and $\overline{y}(t)\in PAA_0(\mathbb{X},\infty,\rho)$.

First, let us prove that $\overline{x}(t)\in AA(\mathbb{X})$.
We consider for each $n=1, 2, \cdots$, the integrals
\begin{equation*}
\overline{x}_n(t)= \int_{t-n}^{t-n+1}A(\sigma)U(t,\sigma)
\overline{\psi}(\sigma)d\sigma.
\end{equation*}
Now, let us show that each $\overline{x}_n(t)\in AA(\mathbb{X})$.
Using the H\"{o}lder inequality and the exponential dissipation property
 of the evolution family $U(t,s)$, it follows that
\begin{align*}
\|\overline{x}_n(t)\|
&\leq\int_{t-n}^{t-n+1}\|A(\sigma)U(t,\sigma)\overline{\psi}(\sigma)\|d\sigma\\
&\leq\int_{t-n}^{t-n+1}\|A(\sigma)U(t,\sigma)\|\|\overline{\psi}(\sigma)\|d\sigma\\
&\leq\int_{t-n}^{t-n+1}H(t-\sigma)e^{-\delta(t-\sigma)}\|\overline{\psi}(\sigma)\|
 d\sigma\\
&\leq\Big(\int_{t-n}^{t-n+1}e^{-\delta q(t-\sigma)}H^{q}(t-\sigma)d\sigma\Big)^{1/q}
\Big(\int_{t-n}^{t-n+1}\|\overline{\psi}(\sigma)\|^p\Big)^{1/p}d\sigma\\
&\leq\Big(\int_{t-n}^{t-n+1}e^{-\delta q(t-\sigma)}H^{q}(t-\sigma)d\sigma\Big)^{1/q}
\|\overline{\psi}(\sigma)\|_{S^p}.
\end{align*}
Using the fact the series
\begin{equation*}
\sum_{n=1}^{\infty}\Big(\int_{t-n}^{t-n+1}e^{-\delta q(t-\sigma)}
H^{q}(t-\sigma)d\sigma\Big)^{1/q}
\end{equation*}
converges, we deduce from the well-known Weierstrass test that the series
$\sum_{n=1}^{\infty}$ $\overline{x}_n(t)$ is uniformly convergent on $\mathbb{R}$.
Let
\begin{equation*}
\overline{x}(t)=\sum_{n=1}^{\infty}\overline{x}_n(t)\quad
\text{for each }t\in\mathbb{R}.
\end{equation*}
Observe that
\begin{equation*}
\overline{x}(t)=\int_{-\infty}^{t}A(s)U(t,s)\overline{\psi}(s)ds \quad
t\in\mathbb{R}.
\end{equation*}
Clearly, $\overline{x}(t)\in C(\mathbb{R},\mathbb{X})$ and
\begin{equation*}
\|\overline{x}(t)\|
\leq \sum_{n=1}^{\infty}\|\overline{x}_n(t)\|
\leq  \sum_{n=1}^{\infty}
 \Big(\int_{t-n}^{t-n+1}e^{-\delta q(t-\sigma)}H^{q}(t-\sigma)d\sigma\Big)^{1/q}
\|\overline{\psi}(\sigma)\|_{S^p}.
\end{equation*}

Since $\overline{\psi}\in AS^p(\mathbb{X})$ and
$A(s)U(t,s)x\in bAA(\mathbb{R},\mathbb{X})$, then for every sequence of real
numbers $\{s_n\}_{n\in \mathbb{N}}$ there exist a subsequence
$\{s_{m}\}_{m\in \mathbb{N}}$ and a function
$\widetilde{\psi}(\cdot)\in L_{\rm loc}^p(\mathbb{R},\mathbb{X})$
such that for each $t\in \mathbb{R}$,
\begin{gather}
\lim_{m\to\infty}\Big(\int_{t}^{t+1}\|\overline{\psi}(s+s_{m})
-\widetilde{\psi}(s)\|^pds\Big)^{1/p}=0, \label{a4.1} \\
\lim_{m\to\infty}\Big(\int_{t}^{t+1}\|\widetilde{\psi}(s-s_{m})
-\overline{\psi}(s)\|^pds\Big)^{1/p}=0, \label{a4.2} \\
\lim_{n\to\infty}A(s+s_n)U(t+s_n,s+s_n)x=U'(t,s)x,\quad
t,s\in\mathbb{R},\; x\in \mathbb{X}, \label{a4.3} \\
\lim_{n\to\infty}U'(t-s_n,s-s_n)x=A(s)U(t,s)x, \quad
t,s\in\mathbb{R}, \; x\in \mathbb{X}. \label{a4.4}
\end{gather}
Let $\widetilde{x}_n=\int_{t-n}^{t-n+1}A(\sigma)U(t,\sigma)
\widetilde{\psi}(\sigma)d\sigma$. Then using H\"{o}lder inequality, we have
\begin{align*}
&\quad  \|\overline{x}_n(t+s_{m})-\widetilde{x}_n(t)\|\\
&=\big\|\int_{t-n}^{t-n+1}[A(\sigma+s_{m})U(t+s_{m},\sigma+s_{m})
 \overline{\psi}(\sigma+s_{m})-A(\sigma)U(t,\sigma)\widetilde{\psi}
 (\sigma)]d\sigma\big\|\\
&\leq \Big\|\int_{t-n}^{t-n+1}A(\sigma+s_{m})U(t+s_{m},
 \sigma+s_{m})(\overline{\psi}(\sigma+s_{m})-\widetilde{\psi}(\sigma))\Big\|\\
&\quad +\Big\|\int_{t-n}^{t-n+1}[A(\sigma+s_{m})U(t+s_{m},\sigma
 +s_{m})\widetilde{\psi}(\sigma)-A(\sigma)U(t,\sigma)\widetilde{\psi}(\sigma)]
 d\sigma\Big\|\\
&=I_n(t)+J_n(t),
\end{align*}
where
\begin{gather*}
I_n(t)=\Big\|\int_{t-n}^{t-n+1}A(\sigma+s_{m})U(t+s_{m},\sigma+s_{m})
(\overline{\psi}(\sigma+s_{m})-\widetilde{\psi}(\sigma))\Big\|, \\
J_n(t)=\Big\|\int_{t-n}^{t-n+1}[A(\sigma+s_{m})U(t+s_{m},\sigma+s_{m})
-A(\sigma)U(t,\sigma)\widetilde{\psi}(\sigma)]d\sigma\Big\|.
\end{gather*}
Then using the H\"{o}lder inequality, we obtain
\begin{align*}
I_n(t)
&\leq\int_{t-n}^{t-n+1}e^{-\delta(t-\sigma)}H(t-\sigma)
 \|\overline{\psi}(\sigma+s_{m})-\widetilde{\psi}(\sigma)\|d\sigma\\
&\leq\Big(\int_{t-n}^{t-n+1}e^{-\delta q(t-\sigma)}H^{q}(t-\sigma)d\sigma\Big)^{1/q}
 \Big(\int_{t-n}^{t-n+1}\|\overline{\psi}(\sigma+s_{m})-\widetilde{\psi}
 (\sigma)\|^pd\sigma\Big)^{1/p}.
\end{align*}
Now using \eqref{a4.1} it follows that $I_n(t)\to0$ as $m\to\infty$ for
each $t\in \mathbb{R}$. Similarly, using the Lebesgue Dominated convergence
Theorem and \eqref{a4.3} it follows that $J_n(t)\to0$ as $m\to\infty$
for each $t\in \mathbb{R}$. Now,
\begin{equation*}
\|\overline{x}_n(t+s_{m})-\widetilde{x}_n(t)\|\to 0,\quad \text{as }m\to\infty.
\end{equation*}
Similarly, using \eqref{a4.2} and \eqref{a4.4}, it can be shown that
\begin{equation*}
\|\widetilde{x}_n(t-s_{m})-\overline{x}_n(t)\|\to 0,\quad \text{as }m\to\infty.
\end{equation*}
Thus, we can conclude that each $\overline{x}_n\in AA(\mathbb{X})$
and consequently their uniform limit $\overline{x}(t)\in AA(\mathbb{X})$.

Next we  verify that $\overline{y}(t)\in PAA_0(\mathbb{X},\infty,\rho)$.
For each $n$=1,2$\cdots$, we consider the integral
\begin{equation*}
\overline{y}_n(t)=\int_{t-n}^{t-n+1}\|A(t,s)U(t,s)\|\,\|\overline{\omega}(s)\|ds.
\end{equation*}

For this we have the following estimates:
\begin{align*}
&\sup_{\theta\in[t-r,t]}\|\overline{y}_n(\theta)\|\\
&\leq \sup_{\theta\in[t-r,t]}\int_{\theta-n}^{\theta-n+1}
 \|A(\theta,s)U(\theta,s)\|\|\overline{\omega}(s)\|ds\\
&\leq \sup_{\theta\in[t-r,t]}\int_{\theta-n}^{\theta-n+1}
 e^{-\delta(\theta-s)}H(\theta-s)\|\overline{\omega}(s)\|ds\\
&\leq \Big(\int_{t-n}^{t-n+1}e^{-\delta q(t-s)}H^{q}(t-s)ds\Big)^{1/q}
\Big(\sup_{\theta\in[t-r,t]}\int_{\theta-n}^{\theta-n+1}
 \|\overline{\omega}(s)\|^pds)^{1/p}\Big).
\end{align*}
Then for $r>0$, we see that
\begin{align*}
&\frac{1}{m(T,\rho)}\int_{-T}^{T}
 \Big(\sup_{\theta\in[t-r,t]}\|\overline{y}_n((\theta)\|\Big)\rho(t)dt\\
&\leq \mathcal{Z}\frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\Big(\int_{\theta-n}^{\theta-n+1}
\|\overline{\omega}(s)\|^pds\Big)^{1/p}\Big)\rho(t)dt,
\end{align*}
where $\mathcal{Z}=\Big(\int_{t-n}^{t-n+1}e^{-\delta q(t-s)}H^{q}(t-s)ds\Big)^{1/q}$.

Since $\overline{\omega}^b\in PAA_0(L^p(0,1,\mathbb{X}),\infty,\rho)$, we have
$\overline{y}_n(t)\in PAA_0(\mathbb{X},\infty,\rho)$ from above
inequality. Then we deduce from the Weierstrass test that the series
$\sum_{n=1}^{\infty}\overline{y}_n(t)$ is uniformly convergent on $\mathbb{R}$,
 Moreover,
\begin{equation*}
\overline{y}(t)=\int_{-\infty}^{t}A(t,s)U(t,s)ds
=\sum_{n=1}^{\infty}\overline{y}_n(t).
\end{equation*}
and clearly $\overline{y}(t)\in C(\mathbb{R},\mathbb{X})$ and
\begin{equation*}
\|\overline{y}(t)\|\leq\sum_{n=1}^{\infty}\|\overline{y}_n(t)\|
\leq \sum_{n=1}^{\infty}\mathcal{Z}\|\overline{\omega}\|_{S^p}.
\end{equation*}
Applying $\overline{y}_n\in PAA_0(\mathbb{X},\infty,\rho)$ and the inequality
\begin{align*}
&\frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\|\overline{y}(\theta)\|\Big)\rho(t)dt\\
&\leq \frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\|\overline{y}(\theta)
 -\sum_{k=1}^{n}\overline{y}_{k}(\theta)\|\Big)\rho(t)dt\\
&\quad+\sum_{k=1}^{\infty}\frac{1}{m(T,\rho)}\int_{-T}^{T}
\Big(\sup_{\theta\in[t-r,t]}\|\overline{y}_{k}(\theta)\|\Big)\rho(t)dt.
\end{align*}
We deduce that the uniformly limit
$\overline{y}(\cdot)=\sum_{n=1}^{\infty}\overline{y}_n(t)
\in PAA_0(\mathbb{X},\infty,\rho)$. Therefore
$v(t)=\overline{x}(t)+\overline{y}(t)$ is weighted pseudo almost automorphic
of class infinity.
\end{proof}

\begin{theorem} \label{thm4.4}
If  conditions {\rm(A6)--(A12)} hold, then  \eqref{a1.1} admits a unique
weighted pseudo almost automorphic mild solution of class infinity provided that
\begin{equation*}
\Theta=\varsigma\Big(L_{f}+\sup_{t\in \mathbb{R}}
\Big(\int_{-\infty}^{t}e^{-\delta q(t-s)}H^{q}(t-s)ds\Big)^{1/q}L_{f}
+\alpha L_{g}\Big)<1,
\end{equation*}
where $\varsigma$ is defined as in Remark \eqref{rem2.24}.
\end{theorem}

\begin{proof}
Define $\mathcal{F}:WPAA(\mathbb{X},\infty)\to WPAA(\mathbb{X},\infty)$ as
\begin{equation*}
(\mathcal{F}u)(t)=-f(t,u_{t})+\int_{-\infty}^{t}U(t,s)g(s,u_{s})ds
-\int_{-\infty}^{t}A(s)U(t,s)f(s,u_{s})ds.
\end{equation*}
If $u\in WPAA(\mathbb{X},\infty)$ by Lemma \ref{lem3.6} and
Corollary \ref{cor3.11}, $g(s,u_{s})\in WPAAS^p(\mathbb{X},\infty)$.
By Lemma \ref{lem3.6} and Corollary \ref{cor3.12},
$f(s,u_{s})\in WPAA(\mathbb{X},\infty)$. Owing to Lemma \ref{lem4.2} and
Lemma \ref{lem4.3}, it is not difficult to see that
$\mathcal{F}(WPAA(\mathbb{X},\infty))\subseteq WPAA(\mathbb{X},\infty)$.
For any $u,v\in WPAA(\mathbb{X},\infty)$, we have
\begin{align*}
&\|(\mathcal{F}u)(t)-(\mathcal{F}v)(t)\|\\
&=\Big\|-f(t,u_{t})+\int_{-\infty}^{t}U(t,s)g(s,u_{s})ds
 -\int_{-\infty}^{t}A(s)U(t,s)f(s,u_{s})ds \\
&\quad +f(t,v_{t})-\int_{-\infty}^{t}U(t,s)g(s,v_{s})ds
 +\int_{-\infty}^{t}A(s)U(t,s)f(s,v_{s})ds\Big\|\\
&\leq L_{f}\|v_{t}-u_{t}\|_{\mathfrak{B}}
+\Big\|\int_0^{\infty}U(t,t-s)(g(t-s,u_{t-s})-g(t-s,v_{t-s}))ds\Big\|\\
&\quad +\Big(\int_{-\infty}^{t}e^{-\delta q(t-s)}H^{q}(t-s)ds\Big)^{1/q}
 L_{f}\|v_{t}-u_{t}\|_{\mathfrak{B}}\\
&\leq L_{f}\|v_{t}-u_{t}\|_{\mathfrak{B}}
 +\Big(\int_{-\infty}^{t}e^{-\delta q(t-s)}H^{q}(t-s)ds\Big)^{1/q}L_{f}
 \|v_{t}-u_{t}\|_{\mathfrak{B}}\\
&\quad +M\sum_{k=1}^{\infty}\Big(\int_{k-1}^{k}e^{-\delta qs}ds\Big)^{1/q}
 \Big(\int_{k-1}^{k}\|g(s,u_{s})-g(s,v_{s})\|^pds\Big)^{1/p}\\
&= L_{f}\|v_{t}-u_{t}\|_{\mathfrak{B}}
 +\Big(\int_{-\infty}^{t}e^{-\delta q(t-s)}H^{q}(t-s)ds\Big)^{1/q}
L_{f}\|v_{t}-u_{t}\|_{\mathfrak{B}}\\
&\quad +\alpha_0\sum_{k=1}^{\infty}e^{-\delta k}\|g(t+k-2+\cdot,u_{t+k-2+\cdot})
 -g(t+k-2+\cdot,v_{t+k-2+\cdot})\|_p\\
&= L_{f}\|v_{t}-u_{t}\|_{\mathfrak{B}}
 +\Big(\int_{-\infty}^{t}e^{-\delta q(t-s)}H^{q}(t-s)ds\Big)^{1/q}
  L_{f}\|v_{t}-u_{t}\|_{\mathfrak{B}}\\
&\quad +\alpha L_{g}\|u_{t+k-2+\cdot}-v_{t+k-2+\cdot}\|_{\mathfrak{B}}\\
&\leq \varsigma\Big(L_{f}+\sup_{t\in \mathbb{R}}
\Big(\int_{-\infty}^{t}e^{-\delta q(t-s)}H^{q}(t-s)ds\Big)^{1/q}L_{f}
 +\alpha L_{g}\Big)\|u-v\|_{\infty}\\
&=\Theta\|u-v\|_{\infty}.
\end{align*}
Consequently,
\[
\|\mathcal{F}u-\mathcal{F}v\|_{\infty}\leq\Theta\|u-v\|_{\infty}.
\]
Then $\mathcal{F}$ is a contraction since $\Theta<1$.
By the Banach contraction mapping principle, $\mathcal{F}$ has a unique
fixed point in $WPAA(\mathbb{X},\infty)$, which is the unique $WPAA$
mild solution to the problem.
\end{proof}

We end this paper with a simple example.
Consider the  first-order boundary-value problem which was used in \cite{DT8},
\begin{equation} \label{a4.5}
\begin{gathered}
\begin{aligned}
&\frac{\partial}{\partial t}\Big[u(t,\xi)
 +\int_{-\infty}^{0}\int_0^{\pi}b(s,\eta,\xi)u(t+s,\eta)d\eta ds\Big]\\
&=\frac{\partial^{2}}{\partial\xi^{2}}u(t,\xi)+a_0(\xi)u(t,\xi)
 +\int_{-\infty}^{0}a(s)u(t+s,\xi)ds,
\end{aligned}\\
u(0,t) = u(\pi,t)=0,
\end{gathered}
\end{equation}
for $t\in \mathbb{R}$ and $\xi\in \mathbb{I}=[0,\pi]$.

Note that equations of type \eqref{a4.5}  arise  in control systems
described by abstract retarded functional-differential equations with
feedback control governed by proportional integro-diffential law,
see \cite{HE12} for details.

To analize \eqref{a4.5}, we let $\mathbb{X}=L^{2}([0,\pi])$ and
$\mathfrak{B}=C((-\infty,0],\mathbb{X})$. In addition, we suppose that
the function $a,a_0,a_1$ are continuous and satisfy the following conditions:

(i) The function $b(\cdot), \frac{\partial^{i}}{\partial\varsigma^{i}}b(\tau$,
$\eta,\varsigma), i$=1,2, are (Lebesgue) measurable,
$b(\tau,\eta,\pi)=0, b(\tau$, $\eta,0)=0$ for every $(\tau,\eta)$ and
\begin{equation*}
N_1=\max\Big\{\int_0^{\pi}\int_{-\infty}^{0}\int_0^{\pi}
\Big(\frac{\partial^{i}}{\partial\varsigma^{i}}b(\tau,\eta,\varsigma)\Big)^{2}
d\eta d\tau d\varsigma:i=0,1,2\Big\}<\infty.
\end{equation*}
Define $f,g:C((-\infty,0],\mathbb{X})$ by
\begin{gather*}
f(t,\psi)(\xi)= \int_{-\infty}^{0}\int_0^{\pi}b(s,\eta,\xi)\psi(s,\eta)d\eta ds,\\
g(t,\psi)(\xi)= a_0(\xi)u(t,\xi)+\int_{-\infty}^{0}a(s)\psi(s,\xi)ds.
\end{gather*}

In view of above arguments, it is clear that \eqref{a4.5} can be rewritten
in the abstract form of \eqref{a1.1}. By direct estimation from (i),
we can show that $f$ takes values in $D(A)$ and that
$f(t,\cdot):C((-\infty,0]:\mathbb{X})\to[D(A)]$ is a bounded linear operator
with $\|Af(t,\cdot)\|\leq(N_1p)^{\frac{1}{2}}$ for each $t\in \mathbb{R}$.
Furthermore, $g$ is a bounded linear operator on $\mathbb{X}$ with
\begin{equation*}
g(t,\cdot)\leq\|a_0\|_{\infty}+\Big(p\Big(\int_{-\infty}^{0}a^{2}(s)ds
\Big)\Big)^{1/2},
\end{equation*}
for every $t\in \mathbb{R}$.

As a consequence of Theorem \ref{thm4.4},  system \eqref{a4.5} has a
unique weighted pseudo almost automorphic mild solution of class infinity whenever
\begin{equation*}
2\sqrt{N_1p}+\|a_0\|_{\infty}
+\Big(p\Big(\int_{-\infty}^{0}a^{2}(s)ds\Big)\Big)^{1/2}<1.
\end{equation*}

\subsection*{Acknowledgments}
The authors are  grateful to the anonymous referee for carefully reading
this manuscript and giving valuable suggestion for improvements.
This work was partially supported by NSFC (11361032), and FRFCUC (JB160713).

\begin{thebibliography}{00}

\bibitem{abbas1}  S. Abbas;
\emph{Pseudo almost automorphic solutions of some nonlinear integro-differential
equations.} Comp. Math. Appl., 62 (2011), 2259--2272.

\bibitem{abbas2} S. Abbas, Y. Xia;
\emph{Existence and attractivity of $k$-almost automorphic solutions of a model
of cellular neural network with delay.}
Acta Mathematica Scientia, 1 (2013), 290--302.

\bibitem{abbas3} S. Abbas;
\emph{Weighted pseudo almost automorphic solutions of fractional functional
 differential equations}, Cubo (Temuco), 16 ( 2014), 21--36.

\bibitem{BS3} S. Bochner;
\emph{Continuous mappings of almost automorphic and almost periodic functions.}
Proc. Ncad. Sci. USA, 52 (1964), 907--910.

\bibitem{BJ4} J. Blot, G. M. Mophou, G. M. N'Gu\'{e}r\'{e}kata, D. Pennequin;
\emph{Weighted pseudo almost automorphic functions and applications to
abstract differential equations.} Nonlinear Anal., 71 (2009), 903--909.

\bibitem{ZR20} Y. K. Chang, R. Zhang,  G. M. N'Gu\'{e}r\'{e}kata;
\emph{Weighted pseudo almost automorphic solutions to nonautonomous
semilinear evolution equations with delay and  $S^p$-weighted pseudo
almost automorphic coefficients.} Topol. Method Nonlinear Anal., 43 (2014), 69--88.


\bibitem{ZR21} Y. K. Chang, M. J. Zhang, R. Ponce;
\emph{Weighted pseudo almost automorphic mild solutions to semilinear
 fractionWeighted pseudo almost automorphic solutions to a semilinear
fractional differential equation with Stepanov-like weighted pseudo almost
automorphic nonlinear term.} Appl. Math. Comput., 257 (2015), 158--168.

\bibitem{DT8} T. Diagana, E. M. Hern\'{a}ndez;
 \emph{Existence and uniqueness of pseudo almost periodic solutions
to some abstract partial neutral functional-differential equations and applications.}
J. Math. Anal. Appl., 327 (2007), 776--791.

\bibitem{DT9} T. Diagana, E. Hern\'{a}ndez, M. Rabello;
\emph{Pseudo almost periodic solutions to some non-autonomous neutral
functional differential equations with unbounded delay.}
Math. Comput. Modelling, 45 (2007), 1241--1252.

\bibitem{DT10} T. Diagana, G. M. N'Gu\'{e}r\'{e}kata;
\emph{Stepanov-like almost automorphic functions and applications to some
semilinear equations}, Appl. Anal., 86 (2007), 723--733.

\bibitem{dia2} T. Diagana;
\emph{Existence of pseudo-almost automorphic solutions
to some abstract differential equations with $S^p$-pseudo-almost automorphic
coefficients.} Nonlinear Anal., 70 (2009), 3781--3790.

\bibitem{DT11} T. Diagana, G. M. Mophou, G. M. N'Gu\'{e}r\'{e}kata;
\emph{Existence of weighted pseudo almost periodic solutions to some
classes of differential equations with $S^p$-weighted pseudo almost
periodic coefficients}, Nonlinear Anal., 72 (2010), 430--438.

\bibitem{Diabook} T. Diagana;
\emph{Almost Automorphic Type and Almost Periodic Type Functions in Abstract
Spaces.} Springer, New York, 2013.

\bibitem{ding7} H. S. Ding, J. Liang, T. J. Xiao;
\emph{Weighted pseudo almost automorphic functions and WPAA solutions
to semilinear evolution equations.} J. Math. Anal. Appl., 409 (2014), 409--427.

\bibitem{flx} Z. B. Fan, J. Liang, T. J. Xiao;
\emph{On Stepanov-like (pseudo) almost automorphic functions.}
Nonlinear Anal., 74 (2011), 2853--2861.


\bibitem{CY7} C. H. Hua, H. X. Li;,
\emph{Composition of $S^p$-weighted pseudo almost automorphic function
and applications.} Electron. J. Diff. Equ., 2014 (2014), 1--15.

\bibitem{henr}H. Henr\'{\i}quez, C. Cuevas;
\emph{Almost automorphy for abstract neutral differential equation via
control theory.} Annali di Matematica,  192 (2013), 393--405.

\bibitem{HE12} E. Hern\'{a}ndez, H. Henriquez;
\emph{Pseudo-almost periodic solutions for non-autonomous neutral
differential euqations with unbounded delay.}  Nonlinear Anal. RWA,
9 (2008), 430--437.

\bibitem{kavitha}
V.  Kavitha, S. Abbas, R. Murugesu;
\emph{Asymptotically almost automorphic solutions of fractional order
 neutral integro-differential equations.} Bull. Malays. Math. Sci. Soc.,
 39 (2016), 1075--1088.


\bibitem{HY13} Y. Hino, S. Murakami, T. Naito;
\emph{Functional-differential equations with infinite delay.}
Springer, Berlin, 1991.

\bibitem{LH14} H. Lee, H. Alkahby;
\emph{Stepanov-like almost automorphic solutions of nonautonomous
semilinear evolution equations with delay.} Nonlinear Anal., 69 (2008), 2158--2166.

\bibitem{LJ15} J. Liang, G. M. N'Gu\'{e}r\'{e}kata, T. J. Xiao, X. X. Zhu;
 \emph{Some properties of pseudo almost automorphic functions and applications to
abstract differential equations.} Nonlinear Anal., 70 (2009), 2731--2735.

\bibitem{NG16}G. M. N'Gu\'{e}r\'{e}kata;
\emph{Almost Automorphic and Almost Periodic Functions in Abstract Spaces.}
Kluwer Academic, New York, 2001.

\bibitem{NG17} G. M. N'Gu\'{e}r\'{e}kata, A. Pankov;
\emph{Stepanov-like almost automorphic functions and monotone evolution equations.}
  Nonlinear Anal., 68 (2008), 2658--2667.

\bibitem{NG18} G. M. N'Gu\'{e}r\'{e}kata;
\emph{Topics in Almost Automorphy.} Springer, New York, 2005.

\bibitem{PA19} A. Pazy;
\emph{Semigroups of Linear Operators and Applications to Partial
Differential Equations.} Springer, New York, 1983.

\bibitem{ponce} R. Ponce;
\emph{Bounded mild solutions to fractional integro-differential
equations in banach spaces.} Semigroup Forum, 87 (2013) 377--392.

\bibitem{sak} R. Sakthivel, P. Revathi, S. Marshal Anthoni;
\emph{Existence of pseudo almost automorphic mild solutions to stochastic fractional
diffenertial equations.} Nonlinear Anal., 75 (2012), 3339--3347.

\bibitem{sak3} R. Sakthivel, P. Revathi, Y. Ren;
\emph{Existence of solutions for nonlinear fractional stochastic
differential equations.} Nonlinear Anal., 81 (2013), 70--86.

\bibitem{xia} Z. N. Xia, M. Fan;
\emph{Weighted Stepanov-like pseudo almost automorphy and applications.}
 Nonlinear Anal., 75 (2012), 2378--2397.

\bibitem{XZ23} Z. N. Xia;
\emph{Weighted pseudo periodic solutions of neutral functional
differential equations.} Electron. J. Diff. Equ., 2014 (2014), 1--17.

\bibitem{XT24} T. J. Xiao, X. X. Zhu, J. Zhang;
\emph{Pseudo-almost automorphic mild solutions to nonautonomous
differential equations and applications.} Nonlinear Anal., 70 (2009), 4079--4085.

\bibitem{ZR22} R. Zhang, Y. K. Chang, G. M. N'Gu\'{e}r\'{e}kata;
\emph{Weighted pseudo almost automorphic solutions for non-autonomous
neutral functional differential equations with infinite delay(in Chinese).}
Sci. Sin. Math., 43 (2013), 273--292.

\end{thebibliography}

\end{document}

