\documentstyle{SibMatJ} % \TestXML \topmatter \Author Liu \Initial Y. \Gender he \Sign Youqi Liu \Email yqliu2021\@163.com \AffilRef 1 \endAuthor \Affil 1 \Division School of Mathematics and Statistics \Organization Chongqing Technology and Business University \City Chongqing \Country China \endAffil \datesubmitted December 29, 2025\enddatesubmitted \daterevised January 20, 2026\enddaterevised \dateaccepted February 16, 2026\enddateaccepted \UDclass ??? %Primary 47B33; Secondary 30H20 \endUDclass \thanks This work was partially supported by the Chongqing Technology and Business University (no. 950323046). %\?grant, номер убрать \endthanks \title Generalized Weighted Composition Operators on Weighted Fock Spaces Induced by $A_{\infty}$-Type Weights \endtitle \abstract In this paper, we characterize the boundedness and compactness of generalized weighted composition operators on weighted Fock spaces $\Cal{F}_{\alpha,\omega}^{p}$ with $\omega\in A_{\infty}^{\roman{restricted}}$. We also study the essential norm of these operators on the weighted Fock spaces. \endabstract \keywords weighted Fock spaces, generalized weighted composition operators, boundedness, essential norm \endkeywords \endtopmatter \let\epsilon\varepsilon %\? \varepsilon не было, только \epsilon всюду \head 1. Introduction \endhead Let $\Cal{H}(\Bbb{C})$ be the space of entire functions on the complex plane $\Bbb{C}$. A function $\omega:\Bbb{C}\rightarrow [0,\infty)$ is a~weight if $\omega$ belongs to $L_{\loc}^{1}(\Bbb{C},dA)$, where $dA$ denotes the Lebesgue measure on $\Bbb{C}$. For $0
0$ a.e. on $\Bbb{C}$ and, for some $r>0$, $$ \Cal{C}_{p,r}(\omega):=\sup\limits_{Q,l(Q)=r}\biggl(\frac{1}{|Q|}\int\limits_{Q}\omega dA \biggr) \biggl( \frac{1}{|Q|}\int\limits_{Q}\omega^{-\frac{p'}{p}} dA \biggr)^{\frac{p}{p'}}<\infty. $$ The pioneering work about the weight class $A_{p}^{\roman{restricted}}$ was done by Isralowitz [2]. In fact, it follows from [2, Theorem~3.1] that these classes of weights are independent of the choice of $r$, and $\omega\in A_{p}^{\roman{restricted}}$ if and only if the orthogonal projection $P_{\alpha}$ is bounded on $\Cal{L}_{\alpha,\omega}^{p}$. The boundedness of projections on $L^{p}$ spaces is a classical topic, which has many applications on operator theory, such as [1,\,3,\,4]. After that, Cascante, F\`abrega, and Pel\'aez [5] investigated a new class of weight $A_{1}^{\roman{restricted}}$. That is, for fixed $r>0$, a weight $\omega\in A_{1}^{\roman{restricted}}$ if $\omega(z)>0$ a.e. on $\Bbb{C}$ and $$ \Cal{C}_{1,r}(\omega):=\sup\limits_{Q,l(Q)=r}\frac{\omega(Q)}{|Q|\text{infess}_{u\in Q}\omega(u)}<\infty. $$ Similarly to %\? Muckenhoupt weights, we denote $$ A_{\infty}^{\roman{restricted}}:=\bigcup\limits_{1\leqslant p<\infty}A_{p}^{\roman{restricted}}. $$ Furthermore, the authors in [5] characterize Littlewood--Paley formulas for weighted Fock spaces $\Cal{F}_{\alpha,\omega}^{p}$ with $\omega\in A_{\infty}^{\roman{restricted}}$. Using Littlewood--Paley formulas, the boundedness of the differentiation and integration operators are also obtained (see [5, Theorem~1.2]). We denote $D^{n}(f)=f^{(n)}$ with $n\in\Bbb{N}$ and $D^{0}(f)=f$. For a positive Borel measure $\mu$ on $\Bbb{C}$, we supplement the compactness of differentiation operator $D^{n}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow L^{q}(\mu)$ with $0
0$.
We write $\Re(z)$ for the real part of a complex number $z$,
and $\omega_{\gamma}(z):=\frac{\omega(z)}{(1+|z|)^{\gamma}}$ with $\gamma\in\Bbb{R}$ (see \Tag(3) for more details).
For a positive Borel measure $\nu$ and $0 0$, $\omega\in A_{\infty}^{\roman{restricted}}$, $n\in \Bbb{N}\cup\{0\}$.
Let $u\in \Cal{F}_{\alpha,\omega}^{p}$ be a~nonzero function and $\varphi(z)=az+b$ with $0<|a|<1$.
If $D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\alpha,\omega}^{p}$ is bounded,
then
$$
\limsup\limits_{|z|\rightarrow\infty}m_{z,n}(u,\varphi)\lesssim \|D^{n}_{\varphi,u}\|_{e}
\lesssim |a|^{-\frac{2}{p}}\limsup\limits_{|z|\rightarrow\infty}\frac{m_{z,n}(u,\varphi)\omega(z)}{\omega(\varphi(z))}.
$$
\endproclaim
The rest of paper contains the proofs of the conclusions as above.
In \Sec*{Section 2}, we provide some auxiliary results.
The proofs of \Par{Theorem 1}{Theorems 1} and \Par{Theorem 2}{2} are given in \Sec*{Section 3}.
Finally, we establish lower and upper estimates for essential norm of the operator $D^{n}_{\varphi,u}$ on weighted Fock spaces $\Cal{F}_{\alpha,\omega}^{p}$ in \Sec*{Section 4}.
In the following, the notation $U(z)\lesssim V(z)$ (or equivalently $V(z)\gtrsim U(z)$) means that there is a~constant $C$ such that $U(z)\leqslant CV(z)$ holds for all $z$ in the set of a question. Furthermore, we write $U(z)\asymp V(z)$ if both $U(z)\lesssim V(z)$ and $V(z)\lesssim U(z)$.
\head
2. Preliminaries
\endhead
By [5, Remark~2.3], if $\omega\in A_{\infty}^{\roman{restricted}}$, for any $t>0$ and $N\in \Bbb{N}$ there is $C=C(\omega,N,p)$ such that
$$
\omega(D(a,t))\leqslant \omega(D(a,Nt))\leqslant C\omega(D(a,t)), \quad a\in\Bbb{C},
$$
and for any $z,w\in \Bbb{C}$ such that $|z-w| 0$, and $\omega\in A_{\infty}^{\roman{restricted}}$. Then, there exists a~constant $C=C(\alpha,p,\omega,t)$ such that
$$
|f(z)|^{p}e^{-\frac{p\alpha}{2}|z|^{2}}\leqslant \frac{C}{\omega(D(z,t))}\int\limits_{D(z,t)}|f(u)|^{p}e^{-\frac{p\alpha}{2}|u|^{2}}\omega(u)dA(u)
$$
for any $z\in\Bbb{C}$ and $f\in \Cal{H}(\Bbb{C})$.
\endproclaim
The following two lemmas generalize
[5, Lemma~3.1 and Corollary~3.2] and [15, Lemmas~2.2 and~2.3] %\?[5, Lemma~3.1 and Corollary~3.2; 15, Lemmas~2.2 and~2.3]
to the weighted Fock spaces $\Cal{F}_{\alpha,\omega}^{p}$.
\proclaim{Lemma 7}
Let $0 0$, $\omega\in A_{\infty}^{\roman{restricted}}$, and $n\in \Bbb{N}\cup\{0\}$. Then there exists a constant $C=C(\alpha,p,\omega,t)$ such that
$$
|f^{(n)}(z)|\leqslant Cn!e^{\frac{\alpha}{2}|z|^{2}}\frac{(1+|z|)^{n}}{\omega(D(z,t))^{\frac{1}{p}}}\|f\|_{\Cal{F}_{\alpha,\omega}^{p}}
$$
for any $z\in\Bbb{C}$ and $f\in \Cal{H}(\Bbb{C})$.
\endproclaim
\demo{Proof}
Firstly, let $n$ be a positive integer.
For $|z|\leqslant1$, \Par*{Lemma 6} and Cauchy integral formula %\?всюду артикль
indicate
$$
\align
|f^{(n)}(z)|&\leqslant \frac{n!}{2\pi}\int\limits_{|z-\zeta|=1}\frac{|f(\zeta)|}{|\zeta-z|^{n+1}}|d\zeta|
\leqslant n!\max\limits_{|z-\zeta|=1}|f(\zeta)|\\
&\leqslant C_{1}n!\|f\|_{\Cal{F}_{\alpha,\omega}^{p}}\max\limits_{|z-\zeta|=1}\frac{e^{\frac{\alpha}{2}|\zeta|^{2}}}{\omega(D(\zeta,t_{1}))^{\frac{1}{p}}}
\leqslant C_{1}C_{2}n!e^{2\alpha}\|f\|_{\Cal{F}_{\alpha,\omega}^{p}}\omega(D(z,t_{2}))^{-\frac{1}{p}}.
\endalign
$$
For $|z|>1$, we conclude from Cauchy integral formula again that
$$
\align
|f^{(n)}(z)|&\leqslant \frac{n!}{2\pi}\int\limits_{|z-\zeta|=|z|^{-1}}\frac{|f(\zeta)|}{|\zeta-z|^{n+1}}|d\zeta|
\leqslant n!|z|^{n}\max\limits_{|z-\zeta|=|z|^{-1}}|f(\zeta)|\\
&\leqslant C_{1}n!|z|^{n}\|f\|_{\Cal{F}_{\alpha,\omega}^{p}}\max\limits_{|\zeta|\leqslant |z|+|z|^{-1}}\frac{e^{\frac{\alpha}{2}|\zeta|^{2}}}{\omega(D(\zeta,t_{1}))^{\frac{1}{p}}}\\
&\leqslant C_{1}C_{2}n!e^{2\alpha}(1+|z|)^{n}\|f\|_{\Cal{F}_{\alpha,\omega}^{p}}
\frac{e^{\frac{\alpha}{2}|z|^{2}}}{\omega(D(z,t_{2}))^{\frac{1}{p}}}.
\endalign
$$
The case $n=0$ follows from [5, Corollary~3.2], which ends this proof.
\qed\enddemo
\proclaim{Lemma 8}
Let $0 0$, $\omega\in A_{\infty}^{\roman{restricted}}$, and let $n$ be a positive integer. Then there exists a constant $C=C(\alpha,p,\omega,t)$ such that
$$
|f^{(n)}(z)e^{-\frac{\alpha}{2}|z|^{2}}|\leqslant Cn!\frac{(1+|z|)^{n}}{\omega(D(z,t))^{\frac{1}{p}}}
\biggl(\int\limits_{D(z,t)}|f(\xi)e^{-\frac{\alpha}{2}|\xi|^{2}}|^{p}\omega(\xi)dA(\xi)\biggr)^{\frac{1}{p}}
$$
for any $z\in\Bbb{C}$ and $f\in \Cal{H}(\Bbb{C})$.
\endproclaim
\demo{Proof}
Let first $|z|\leqslant1$. By the joining of \Par*{Lemma 6} and the proof of \Par*{Lemma 7}, we have
$$
\align
|f^{(n)}(z)e^{-\frac{\alpha}{2}|z|^{2}}|
&\leqslant |f^{(n)}(z)|
\leqslant n!(1+|z|)^{n}\max\limits_{|z-\zeta|=1}|f(\zeta)|\\
&\leqslant C_{1}n!(1+|z|)^{n}\max\limits_{|\zeta|\leqslant2}
\biggl(\omega(D(\zeta,r_{0}))^{-1}\int\limits_{D(\zeta,r_{0})}|f(u)e^{-\frac{\alpha}{2}|u|^{2}}|^{p}\omega(u)dA(u)\biggr)^{\frac{1}{p}}\\
&\leqslant C_{1}C_{2}n!(1+|z|)^{n}\omega(D(z,3))^{-\frac{1}{p}}
\biggl(\ \int\limits_{D(z,3)}|f(u)e^{-\frac{\alpha}{2}|u|^{2}}|^{p}\omega(u)dA(u)\biggr)^{\frac{1}{p}}.
\endalign
$$
If $|z|>1$, then we obtain
$$
\align
|f^{(n)}(z)e^{-\frac{\alpha}{2}|z|^{2}}|
&\leqslant n!|z|^{n}e^{-\frac{\alpha|z|^{2}}{2}}\max\limits_{|z-\zeta|\leqslant|z|^{-1}}|f(\zeta)|\\
&\leqslant C_{1}n!|z|^{n}e^{-\frac{\alpha|z|^{2}}{2}}\max\limits_{|z-\zeta|\leqslant|z|^{-1}}
\frac{e^{\frac{\alpha}{2}|\zeta|^{2}}}{\omega(D(\zeta,r_{1}))^{\frac{1}{p}}}
\biggl(\ \int\limits_{D(\zeta,r_{1})}|f(u)e^{-\frac{\alpha}{2}|u|^{2}}|^{p}\omega(u)dA(u)\biggr)^{\frac{1}{p}}\\
&\lesssim n!\frac{(1+|z|)^{n}}{\omega(D(z,r_{1}))^{\frac{1}{p}}}\max\limits_{|z-\zeta|\leqslant|z|^{-1}}
\biggl(\ \int\limits_{D(\zeta,r_{1})}|f(u)e^{-\frac{\alpha}{2}|u|^{2}}|^{p}\omega(u)dA(u)\biggr)^{\frac{1}{p}}\\
&\lesssim n!\frac{(1+|z|)^{n}}{\omega(D(z,r_{2}))^{\frac{1}{p}}}
\biggl(\ \int\limits_{D(z,r_{1}+1)}|f(u)e^{-\frac{\alpha}{2}|u|^{2}}|^{p}\omega(u)dA(u)\biggr)^{\frac{1}{p}}.
\endalign
$$
This completes the proof.
\qed\enddemo
The following lemma, see [16, Lemma~4.10] or [17, Lemma~3.7], plays a key role to study compactness of linear operators.
\proclaim{Lemma 9}
Let $X$ and $Y$ be two Banach {\rm(}or quasi-Banach{\rm)} spaces of entire functions on $\Bbb{C}$, and let $T: X\rightarrow Y$ be a linear operator. Suppose that the following conditions are satisfied:
\Item (i) The point evaluation functionals on $Y$ are bounded.
\Item (ii) The closed unit ball of $X$ is a compact subset of $\Cal{H}(\Bbb{C})$, where $\Cal{H}(\Bbb{C})$ is endowed with the topology of uniform convergence on compacta.
\Item (iii) $T: X\rightarrow Y$ is continuous, where both $X$ and $Y$ are endowed with the topology of uniform convergence on compacta.\par
Then $T: X\rightarrow Y$ is a compact operator if and only if for any bounded sequence $\{f_{j}\}$ in $X$ such that $f_{j}\rightarrow0$ uniformly on compact subset %\?
of $\Bbb{C}$ as $j\rightarrow\infty$, the sequence $\{Tf_{j}\}$ converges to zero in the norm of $Y$ as $j\rightarrow\infty$.
\endproclaim
\head
3. Proofs of \Par{Theorem 1}{Theorems~1} and~\Par{Theorem 2}{2}
\endhead
In this section, we will provide the boundedness and compactness of generalized weighted composition operator %\?the
$D^{n}_{\varphi,u}$ between different spaces.
At first, we consider the compactness of differentiation operator %\?
$D^{n}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow L^{q}(\mu)$ with $0 0$, the open balls $B(f_{a},\epsilon)=\{f\in L^{q}(\mu):\|f_{a}-f\|_{L^{q}(\mu)}<\epsilon\}$ cover the closure of the set $\{f_{a}:a\in\Bbb{C}\}$.
Then there is a~finite subcover $\{B(f_{a_{n}},\epsilon):n=1,\dots,N=N(\epsilon)\}$. For each $a\in \Bbb{C}$, let $j=j(a)\in \{1,\dots,N\}$ such that $f_{a}\in B(f_{a_{j}},\epsilon)$. Therefore, for each $R>0$,
$$
\align
\int\limits_{\Bbb{C}\setminus D(0,R)}|f_{a}(z)|^{q}d\mu(z)
&\lesssim
\int\limits_{\Bbb{C}\setminus D(0,R)}|f_{a}(z)-f_{a_{j}}(z)|^{q}d\mu(z)+\int\limits_{\Bbb{C}\setminus D(0,R)}|f_{a_{j}}(z)|^{q}d\mu(z)\\
&\leqslant \|f_{a}-f_{a_{j}}\|^{q}_{L^{q}(\mu)}+\max\limits_{n=1,\dots,N}\int\limits_{\Bbb{C}\setminus D(0,R)}|f_{a_{n}}(z)|^{q}d\mu(z),
\endalign
$$
and so
$$
\lim\limits_{R\rightarrow\infty}\int\limits_{\Bbb{C}\setminus D(0,R)}|f_{a}(z)|^{q}d\mu(z)=0
$$
uniformly in $a$. Combining with the uniform convergence, we deduce
$$
\align
0=\lim\limits_{|a|\rightarrow\infty}\|f_{a}\|^{q}_{L^{q}(\mu)}
&\geqslant\lim\limits_{|a|\rightarrow\infty}\int\limits_{D(a,1)}|f_{a}(z)|^{q}d\mu(z)\\
&=\lim\limits_{|a|\rightarrow\infty}\omega(D(a,1))^{-\frac{q}{p}}
\int\limits_{D(a,1)}e^{\frac{q\alpha}{2}|z|^{2}-\frac{q\alpha}{2}|z-a|^{2}}d\mu(z)\\
&\gtrsim\lim\limits_{|a|\rightarrow\infty}\omega(D(a,1))^{-\frac{q}{p}}
\int\limits_{D(a,1)}e^{\frac{q\alpha}{2}|z|^{2}}d\mu(z).
\endalign
$$
Conversely, assume \Par{T11}{(ii)} holds, let $\{f_{k}\}_{k}\in \Cal{F}_{\alpha,\omega}^{p}$ be a sequence such that $\sup\nolimits_{k\in \Bbb{N}}\|f_{k}\|_{\Cal{F}_{\alpha,\omega}^{p}}=M<\infty$. Then we conclude from [5, Corollary~3.2] that $\{f_{k}\}_{k}$ is uniformly bounded on compact subsets of $\Bbb{C}$. With the help of Montel's theorem and Weierstrass' theorem, there is a subsequence $\{f_{k_{j}}\}_{j}$ converges uniformly %\?which converges uniformly or that converges uniformly
on compact subsets of $\Bbb{C}$ to a function $f$ which is in $\Cal{H}(\Bbb{C})$. And thus $f\in \Cal{F}_{\alpha,\omega}^{p}$ by Fatou's lemma.
Set $|a_{n}|\rightarrow\infty$ as $n\rightarrow\infty$. Then the hypothesis gives that, for any $\epsilon>0$, there exists $N=N(\epsilon)\in\Bbb{N}$ such that
$$
\frac{1}{(\omega(D(a_{n},1)))^{\frac{q}{p}}}\int\limits_{D(a_{n},1)}e^{\frac{q\alpha |z|^{2}}{2}}d\mu(z)<\epsilon.
$$
This together with \Tag(1), \Par*{Lemma 6}, and Minkowski's inequality in continuous form (Fubini's theorem in the case $p=q$)
shows %\?that
$$
\align
\sum\limits_{n=N}^{\infty}
&\int\limits_{D(a_{n},1)}|f(z)-f_{k_{j}}(z)|^{q}d\mu(z)\\
&\lesssim \sum\limits_{n=N}^{\infty}\int\limits_{D(a_{n},1)}\frac{e^{\frac{q\alpha}{2}|z|^{2}}}{\omega(D(z,1))^{\frac{q}{p}}}
\biggl(\ \int\limits_{D(z,1)}|f(u)-f_{k_{j}}(u)|^{p}e^{-\frac{p\alpha}{2}|u|^{2}}\omega(u)dA(u)\biggr)^{\frac{q}{p}}d\mu(z)\\
&\leqslant \sum\limits_{n=N}^{\infty}
\biggl[\,\int\limits_{\{u:D(z,1)\cap D(a_{n},1)\neq\emptyset\}}|f(u)-f_{k_{j}}(u)|^{p}e^{-\frac{p\alpha}{2}|u|^{2}}
\biggl(\frac{\int_{D(a_{n},1)}e^{\frac{q\alpha}{2}|z|^{2}}d\mu(z)}{\omega(D(z,1))^{\frac{q}{p}}}
\biggr)^{\frac{p}{q}}\omega(u)dA(u)\biggr]^{\frac{q}{p}}\\
&\lesssim \epsilon\sum\limits_{n=N}^{\infty}
\biggl(\ \int\limits_{\{u:D(z,1)\cap D(a_{n},1)\neq\emptyset\}}|f(u)-f_{k_{j}}(u)|^{p}e^{-\frac{p\alpha}{2}|u|^{2}}
\omega(u)dA(u)\biggr)^{\frac{q}{p}}\\
&\lesssim \epsilon\|f-f_{k_{j}}\|_{\Cal{F}_{\alpha,\omega}^{p}}^{q}\leqslant \epsilon M^{q}.
\endalign
$$
Therefore,
$$
\align
&\limsup\limits_{j\rightarrow\infty}\int\limits_{\Bbb{C}}|f(z)-f_{k_{j}}(z)|^{q}d\mu(z)\\
&\qquad\leqslant \limsup\limits_{j\rightarrow\infty}\Biggl(\sum\limits_{n=1}^{N-1}\int\limits_{D(a_{n},1)}|f(z)-f_{k_{j}}(z)|^{q}d\mu(z)
+\sum\limits_{n=N}^{\infty}\int\limits_{D(a_{n},1)}|f(z)-f_{k_{j}}(z)|^{q}d\mu(z)\Biggr)\lesssim\epsilon,
\endalign
$$
because of
$$
\lim\limits_{j\rightarrow\infty}\sum\limits_{n=1}^{N-1}\int\limits_{D(a_{n},1)}|f(z)-f_{k_{j}}(z)|^{q}d\mu(z)=0
$$
by the uniform convergence in compact subsets.
And hence, for any $\epsilon>0$, we get
$$
\limsup\limits_{j\rightarrow\infty}\int\limits_{\Bbb{C}}|f(z)-f_{k_{j}}(z)|^{q}d\mu(z)=0,
$$
which concludes $I_{d}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow L^{q}(\mu)$ is compact.
Next, by [5, Lemma~2.1], we have
$$
\omega\in A_{\infty}^{\roman{restricted}} \Leftrightarrow \omega_{\gamma}(z)=\frac{\omega(z)}{(1+|z|)^{\gamma}}\in A_{\infty}^{\roman{restricted}}.
\tag3
$$
Now, combining \Par*{Lemma 9}, the proof for case $n\in\Bbb{N}$ is an analog of above, %\?the
we omit the details here, and the desired consequences are complete.
\qed\enddemo
We use $\mu_{\varphi}^{\beta,\nu}(|u|^{q})$ to denote the positive measure on $\Bbb{C}$ defined by
$$
\mu_{\varphi}^{\beta,\nu}(|u|^{q})(E)=\int\limits_{\varphi^{-1}(E)}|u(z)|^{q}e^{-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)
$$
for every Borel subset $E$ of $\Bbb{C}$.
Next, we study the boundedness and compactness of $D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\beta,\nu}^{q}$ with $0 0$, $\omega\in A_{\infty}^{\roman{restricted}}$, $n\in \Bbb{N}\cup\{0\}$, and $\nu$ is a weight.
Let $\varphi$ be an analytic self-map of $\Bbb{C}$ and $u\in \Cal{F}_{\beta,\nu}^{q}$.
Then $D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\beta,\nu}^{q}$ is bounded if and only if
$$
\sup\limits_{a\in \Bbb{C}}\int\limits_{\Bbb{C}}\frac{|u(z)|^{q}}{\omega_{np}(D(a,1))^{q/p}} e^{q\alpha \Re(\overline{a}\varphi(z))-\frac{q\alpha}{2}|a|^{2}-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)<\infty.
\tag4
$$
\endproclaim
\demo{Proof}
Assume that $D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\beta,\nu}^{q}$ is bounded. It follows that
$$
\align
\|D^{n}_{\varphi,u}f_{a}\|_{\Cal{F}_{\beta,\nu}^{q}}^{q}
&=(\alpha|a|)^{qn}\int\limits_{\Bbb{C}}
\frac{|u(z)|^{q}}{\omega(D(a,1))^{q/p}} e^{q\alpha \Re(\overline{a}\varphi(z))-\frac{q\alpha}{2}|a|^{2}-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)\\
&\asymp \int\limits_{\Bbb{C}}
\frac{|u(z)|^{q}}{\omega_{np}(D(a,1))^{q/p}} e^{q\alpha \Re(\overline{a}\varphi(z))-\frac{q\alpha}{2}|a|^{2}-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)
\leqslant C\|f_{a}\|_{\Cal{F}_{\alpha,\omega}^{p}}^{q}<\infty,
\endalign
$$
which concludes \Tag(4).
Conversely, suppose that \Tag(4) holds. Thus,
$$
\align
\infty&>\int\limits_{\Bbb{C}}\frac{|u(z)|^{q}}{\omega_{np}(D(a,1))^{q/p}} e^{q\alpha \Re(\overline{a}\varphi(z))-\frac{q\alpha}{2}|a|^{2}-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)\\
&\geqslant \int\limits_{\varphi^{-1}(D(a,1))}\frac{|u(z)|^{q}}{\omega_{np}(D(a,1))^{q/p}} e^{q\alpha \Re(\overline{a}\varphi(z))-\frac{q\alpha}{2}|a|^{2}-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)\\
&= \int\limits_{D(a,1)}\omega_{np}(D(a,1))^{-q/p} e^{\frac{q\alpha}{2}|z|^{2} -\frac{q\alpha}{2}|z-a|^{2}}d\mu_{\varphi}^{\beta,\nu}(|u|^{q})(z)\\
&\gtrsim \frac{1}{\omega_{np}(D(a,1))^{q/p}}\int\limits_{D(a,1)}e^{\frac{q\alpha |z|^{2}}{2}}d\mu_{\varphi}^{\beta,\nu}(|u|^{q})(z).
\endalign
$$
Using Theorem [5, Theorem~1.2], %\?
we deduce $\|f^{(n)}\|_{L_{\mu_{\varphi}^{\beta,\nu}(|u|^{q})}^{q}}\lesssim \|f\|_{\Cal{F}_{\alpha,\omega}^{p}}$ with $f\in\Cal{F}_{\alpha,\omega}^{p}$, and hence
$D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\beta,\nu}^{q}$ is bounded since
$\|D_{\varphi,u}^{n}f\|_{\Cal{F}_{\beta,\nu}^{q}}= \|f^{(n)}\|_{L_{\mu_{\varphi}^{\beta,\nu}(|u|^{q})}^{q}}$.
This finishes the proof.
\qed\enddemo
\proclaim{Theorem 13}
Suppose that $0 0$, $\omega\in A_{\infty}^{\roman{restricted}}$, $n\in \Bbb{N}\cup\{0\}$, and $\nu$ is a weight.
Let $\varphi$ be an analytic self-map of $\Bbb{C}$ and $u\in \Cal{F}_{\beta,\nu}^{q}$.
Then $D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\beta,\nu}^{q}$ is compact if and only if
$$
\lim\limits_{|a|\rightarrow\infty}\int\limits_{\Bbb{C}}\frac{|u(z)|^{q}}{\omega_{np}(D(a,1))^{q/p}} e^{q\alpha \Re(\overline{a}\varphi(z))-\frac{q\alpha}{2}|a|^{2}-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)=0.
\tag5
$$
\endproclaim
\demo{Proof}
Assume that $D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\beta,\nu}^{q}$ is compact. Set the function $f_{a}$ as in \Tag(2).
Then we obtain $\|f_{a}\|_{\Cal{F}_{\alpha,\omega}^{p}}\asymp1$ and $f_{a}$ tends to zero uniformly on compact subsets of $\Bbb{C}$ as $|a|$ goes to $\infty$.
And thus, $\|D^{n}_{\varphi,u}f_{a}\|_{\Cal{F}_{\beta,\nu}^{q}}\rightarrow0$ when $|a|\rightarrow\infty$.
It follows that
$$
\align
\lim\limits_{|a|\rightarrow\infty}\|D^{n}_{\varphi,u}f_{a}\|_{\Cal{F}_{\beta,\nu}^{q}}^{q}
&=\lim\limits_{|a|\rightarrow\infty}(\alpha|a|)^{qn}\int\limits_{\Bbb{C}}
\frac{|u(z)|^{q}}{\omega(D(a,1))^{q/p}} e^{q\alpha \Re(\overline{a}\varphi(z))-\frac{q\alpha}{2}|a|^{2}-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)\\
&\asymp \lim\limits_{|a|\rightarrow\infty}\int\limits_{\Bbb{C}}
\frac{|u(z)|^{q}}{\omega_{np}(D(a,1))^{q/p}} e^{q\alpha \Re(\overline{a}\varphi(z))-\frac{q\alpha}{2}|a|^{2}-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)=0,
\endalign
$$
which indicates \Tag(5).
Conversely, suppose that \Tag(5) holds. By the joining of \Par*{Theorem 11} and the proof of \Par*{Theorem 12}, it is enough to show
$$
\lim\limits_{|a|\rightarrow\infty}\frac{1}{\omega_{np}(D(a,1))^{q/p}}\int\limits_{D(a,1)}e^{\frac{q\alpha |z|^{2}}{2}}d\mu_{\varphi}^{\beta,\nu}(|u|^{q})(z)=0.
$$
Since
$$
\align
0&=\lim\limits_{|a|\rightarrow\infty}\int\limits_{\Bbb{C}}\frac{|u(z)|^{q}}{\omega_{np}(D(a,1))^{q/p}} e^{q\alpha \Re(\overline{a}\varphi(z))-\frac{q\alpha}{2}|a|^{2}-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)\\
&\geqslant \lim\limits_{|a|\rightarrow\infty}\int\limits_{\varphi^{-1}(D(a,1))}\frac{|u(z)|^{q}}{\omega_{np}(D(a,1))^{q/p}} e^{q\alpha \Re(\overline{a}\varphi(z))-\frac{q\alpha}{2}|a|^{2}-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)\\
&= \lim\limits_{|a|\rightarrow\infty}\int\limits_{D(a,1)}\omega_{np}(D(a,1))^{-q/p} e^{\frac{q\alpha}{2}|z|^{2} -\frac{q\alpha}{2}|z-a|^{2}}d\mu_{\varphi}^{\beta,\nu}(|u|^{q})(z)\\
&\gtrsim \lim\limits_{|a|\rightarrow\infty}\frac{1}{\omega_{np}(D(a,1))^{q/p}}\int\limits_{D(a,1)}e^{\frac{q\alpha |z|^{2}}{2}}d\mu_{\varphi}^{\beta,\nu}(|u|^{q})(z),
\endalign
$$
we deduce that
$D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\beta,\nu}^{q}$ is compact, and the proof is complete.
\qed\enddemo
Suppose $0 0$, $\omega\in A_{\infty}^{\roman{restricted}}$, $n\in \Bbb{N}\cup\{0\}$, and $\varphi$ is an analytic self-map of $\Bbb{C}$.
Let $u$ be a nonzero entire function on $\Bbb{C}$.
If $D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\alpha,\omega}^{q}$ is bounded,
then $u\in \Cal{F}_{\alpha,\omega}^{q}$. In this case,
$\varphi(z)=az+b$ with $|a|<1$ and
$$
|u(z)||\varphi(z)|^{n}e^{\frac{3\alpha|\varphi(z)|^{2}}{4}-\frac{3\alpha|z|^{2}}{4}}
\lesssim \|D^{n}_{\varphi,u}f_{\varphi(z)}\|_{\Cal{F}_{\alpha,\omega}^{q}}\leqslant \|D^{n}_{\varphi,u}\|
$$
for any $z\in \Bbb{C}$.
\endproclaim
\demo{Proof}
If $f(z)=z^{n}$, then we have $u\in \Cal{F}_{\alpha,\omega}^{q}$ by the boundedness of $D^{n}_{\varphi,u}$.
Setting $f_{a}$ as in \Tag(2).
For any $a,z\in \Bbb{C}$, we conclude from \Par*{Lemma 4} that there are constants $C_{1},C_{2}>0$ such that
$$
\omega(D(z,1))\geqslant C_{1}^{-|z|}\omega(D(0,1))\quad\text{and}\quad \omega(D(a,1))\leqslant C_{2}^{|a|}\omega(D(0,1)).
\tag7
$$
This together with \Par*{Lemma 7} yields
$$
\align
\|D^{n}_{\varphi,u}f_{a}\|_{\Cal{F}_{\alpha,\omega}^{q}}&\gtrsim |D^{n}_{\varphi,u}f_{a}(z)|\omega(D(z,1))^{\frac{1}{q}}e^{-\frac{\alpha|z|^{2}}{2}}\\
&=|u(z)|\frac{\omega(D(z,1))^{\frac{1}{q}}}{\omega(D(a,1))^{\frac{1}{p}}}(\alpha|a|)^{n}e^{\alpha \Re(\overline{a}\varphi(z))-\frac{\alpha|a|^{2}}{2}-\frac{\alpha|z|^{2}}{2}}\\
&\geqslant C_{1}^{-\frac{|z|}{q}}C_{2}^{-\frac{|a|}{p}}|u(z)|\omega(D(0,1))^{\frac{1}{q}-\frac{1}{p}}(\alpha|a|)^{n}e^{\alpha \Re(\overline{a}\varphi(z))-\frac{\alpha|a|^{2}}{2}-\frac{\alpha|z|^{2}}{2}}.
\endalign
$$
Setting $a=\varphi(z)$, we deduce
$$
C_{1}^{-\frac{|z|}{q}}C_{2}^{-\frac{|\varphi(z)|}{p}}|u(z)||\varphi(z)|^{n}e^{\frac{\alpha|\varphi(z)|^{2}}{2}-\frac{\alpha|z|^{2}}{2}}
\lesssim \|D^{n}_{\varphi,u}f_{\varphi(z)}\|_{\Cal{F}_{\alpha,\omega}^{q}}\leqslant \|D^{n}_{\varphi,u}\|.
$$
Note that
$$
C_{1}^{-\frac{|z|}{q}}C_{2}^{-\frac{|\varphi(z)|}{p}}e^{\frac{\alpha|\varphi(z)|^{2}}{2}-\frac{\alpha|z|^{2}}{2}}
\geqslant C_{1}^{-\frac{|z|}{q}}e^{-\frac{\alpha|z|^{2}}{4}}C_{2}^{-\frac{|\varphi(z)|}{p}}e^{\frac{-\alpha|\varphi(z)|^{2}}{4}}
e^{\frac{3\alpha|\varphi(z)|^{2}}{4}-\frac{3\alpha|z|^{2}}{4}},
$$
it follows that
$$
|u(z)||\varphi(z)|^{n}e^{\frac{3\alpha|\varphi(z)|^{2}}{4}-\frac{3\alpha|z|^{2}}{4}}
\lesssim \|D^{n}_{\varphi,u}f_{\varphi(z)}\|_{\Cal{F}_{\alpha,\omega}^{q}}\leqslant \|D^{n}_{\varphi,u}\|.
$$
Hence, by \Par*{Lemma 15} we get $\varphi(z)=az+b$ with $|a|\leqslant1$. However, if $|a|=1$, then Liouville's theorem and \Par*{Lemma 15} indicate $u(z)\varphi(z)^{n}\equiv0$, and hence $u(z)=0$ since $\varphi(z)\neq0$.
The proof of this theorem is complete.
\qed\enddemo
\proclaim{Corollary 17}
Suppose that $0 0$, $\omega\in A_{\infty}^{\roman{restricted}}$, $n\in \Bbb{N}\cup\{0\}$,
and $u$ is a nonzero analytic function in $\Cal{F}_{\alpha,\omega}^{q}$.
If $\varphi(z)=b$, then $D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\alpha,\omega}^{q}$ is compact, and
there are constants $C_{1},C_{2}>0$ such that
$$
C_{1}^{-\frac{|b|}{p}}|b|^{n}e^{\frac{\alpha|b|^{2}}{2}}\|u\|_{\Cal{F}_{\alpha,\omega}^{q}}\lesssim \|D^{n}_{\varphi,u}\|
\lesssim C_{2}^{\frac{|b|}{p}}(1+|b|)^{n}e^{\frac{\alpha|b|^{2}}{2}}\|u\|_{\Cal{F}_{\alpha,\omega}^{q}}.
$$
\endproclaim
\demo{Proof}
For $g\in \Cal{F}_{\alpha,\omega}^{p}$, it follows from \Par*{Lemma 7} and \Tag(7) that
$$
\|D^{n}_{\varphi,u}g\|_{\Cal{F}_{\alpha,\omega}^{q}}
\lesssim C_{2}^{\frac{|b|}{p}}(1+|b|)^{n}e^{\frac{\alpha|b|^{2}}{2}}\|g\|_{\Cal{F}_{\alpha,\omega}^{p}}\|u\|_{\Cal{F}_{\alpha,\omega}^{q}}.
$$
Letting $f_{b}$ as in \Tag(2). %\?
Using \Tag(7) again, we obtain
$$
\|D^{n}_{\varphi,u}f_{b}\|_{\Cal{F}_{\alpha,\omega}^{q}}
\gtrsim C_{1}^{-\frac{|b|}{p}}|b|^{n}e^{\frac{\alpha|b|^{2}}{2}}\|u\|_{\Cal{F}_{\alpha,\omega}^{q}}.
$$
Furthermore, $D^{n}_{\varphi,u}$ is a finite rank operator with rank 1, and so it is compact.
This finishes the proof.
\qed\enddemo
For entire functions $u$ and $\varphi$ on $\Bbb{C}$, we denote
$$
m_{z,n}(u,\varphi)=|u(z)||\varphi(z)|^{n}e^{\frac{|\varphi(z)|^{2}-|z|^{2}}{2}}, \quad z\in\Bbb{C}.
$$
In view of \Par*{Theorem 16} and \Par*{Corollary 17}, we study the essential norm of $D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\alpha,\omega}^{p}$ when
$\varphi(z)=az+b$ with $0<|a|<1$.
\proclaim{Theorem 18}
Suppose that $1 0$, $\omega\in A_{\infty}^{\roman{restricted}}$, $n\in \Bbb{N}\cup\{0\}$.
Let $u\in \Cal{F}_{\alpha,\omega}^{q}$ be a nonzero function and $\varphi(z)=az+b$ with $0<|a|<1$. If $D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\alpha,\omega}^{q}$ is bounded,
then
$$
\limsup\limits_{|z|\rightarrow\infty}m_{z,n}(u,\varphi)\lesssim \|D^{n}_{\varphi,u}\|_{e}.
$$
\endproclaim
\demo{Proof}
It follows from \Par*{Theorem 16} that $\limsup\nolimits_{|z|\rightarrow\infty}m_{z,n}(u,\varphi)<\infty$, and there is a constant $C_{0}>0$ so that $m_{z,n}(u,\varphi)\leqslant C_{0}\|D^{n}_{\varphi,u}f_{\varphi(z)}\|_{\Cal{F}_{\alpha,\omega}^{q}}$. Assume that
$$
C_{0}\|D^{n}_{\varphi,u}\|_{e}<\limsup\limits_{|z|\rightarrow\infty}m_{z,n}(u,\varphi).
$$
Then there exist positive constants $C_{1},C_{2}$ and a compact operators $T:\Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\alpha,\omega}^{q}$ such that
$$
C_{0}\|D^{n}_{\varphi,u}-T\|0$, $\omega\in A_{\infty}^{\roman{restricted}}$, $n\in \Bbb{N}\cup\{0\}$, and $\nu$ is a weight.
Let $\varphi$ be an analytic self-map of $\Bbb{C}$ and $u\in \Cal{F}_{\beta,\nu}^{q}$.
Then:
\Item (i) $D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\beta,\nu}^{q}$ is bounded if and only if
$$
\sup\limits_{a\in \Bbb{C}}\int\limits_{\Bbb{C}}\frac{|u(z)|^{q}}{\omega_{np}(D(a,1))^{q/p}} e^{q\alpha \Re(\overline{a}\varphi(z))-\frac{q\alpha}{2}|a|^{2}-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)<\infty.
$$
\Item (ii)
$D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\beta,\nu}^{q}$ is compact if and only if
$$
\lim\limits_{|a|\rightarrow\infty}\int\limits_{\Bbb{C}}\frac{|u(z)|^{q}}{\omega_{np}(D(a,1))^{q/p}} e^{q\alpha \Re(\overline{a}\varphi(z))-\frac{q\alpha}{2}|a|^{2}-\frac{q\beta}{2}|z|^{2}}\nu(z)dA(z)=0.
$$
\endproclaim
In addition to boundedness and compactness, we intend to consider the essential norm of the generalized weighted composition operator $D^{n}_{\varphi,u}$.
For classical Fock spaces $F_{\alpha}^{p}$, Tien and Khoi [12] provided lower and upper estimates for essential norm of weighted composition operator $uC_{\varphi}$.
Later on, Hu, Li, and Qu [15] extended these estimates for the operator $D^{n}_{\varphi,u}$ on the Fock spaces $F_{\alpha}^{p}$.
Inspired by these papers, we investigate lower and upper estimates for essential norm of the operator $D^{n}_{\varphi,u}$ on weighted Fock spaces $\Cal{F}_{\alpha,\omega}^{p}$ via Littlewood--Paley formulas (see [5, Theorem~1.1]).
Combining \Par*{Theorem 16} with \Par*{Corollary 17} below, we offer these estimates of $D^{n}_{\varphi,u}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow \Cal{F}_{\alpha,\omega}^{p}$ whenever $\varphi(z)=az+b$ with $0<|a|<1$.
\proclaim{Theorem 3}
Suppose that $1
0$. Due to the hypothesis, %\?
there is $R>0$ such that
$$
\int\limits_{\Bbb{C}\setminus \overline{D(0,R)}}\biggl(\frac{(1+|\xi|)^{nq}}{\omega(D(\xi,1))}
\int\limits_{D(\xi,1)}e^{\frac{q\alpha}{2}|z|^{2}}d\mu(z)\biggr)^{p/(p-q)}\omega(\xi)dA(\xi)\leqslant \epsilon^{p/(p-q)}.
$$
Since $\{f_{k}\}$ uniformly converge %\?
on compact subsets of $\Bbb{C}$ as $k\rightarrow\infty$, we may choose $k_{0}\in \Bbb{N}$ such that
$|f_{k}(\xi)|^{q}<\epsilon$ whenever $k\geqslant k_{0}$ and $\xi\in \overline{D(0,R)}$.
Therefore,
$$
\align
\|D^{n}f_{k}\|^{q}_{L^{q}(d\mu)}
&\lesssim
\biggl(\ \int\limits_{\overline{D(0,R)}}+\int\limits_{\Bbb{C}\setminus \overline{D(0,R)}}\biggr)
|f_{k}(\xi)e^{-\frac{\alpha}{2}|\xi|^{2}}|^{q}\\
&\cdot %\?\times
\frac{(1+|\xi|)^{nq}}{\omega(D(\xi,1))}\int\limits_{D(\xi,1)}e^{\frac{q\alpha}{2}|z|^{2}}d\mu(z)\omega(\xi)dA(\xi)\\
&\lesssim \sup\limits_{\xi\in \overline{D(0,R)}}\frac{(1+|\xi|)^{nq}}{\omega(D(\xi,1))}\int\limits_{D(\xi,1)}e^{\frac{q\alpha}{2}|z|^{2}}d\mu(z)
\int\limits_{\overline{D(0,R)}}|f_{k}(\xi)|^{q}\omega(\xi)dA(\xi)\\
&\qquad +\biggl(\int\limits_{\Bbb{C}}|f_{k}(\xi)|^{p}\omega(\xi)dA(\xi)\biggr)^{q/p}\\
& \cdot %\?
\biggl(\ \int\limits_{\Bbb{C}\setminus \overline{D(0,R)}}\biggl(\frac{(1+|\xi|)^{nq}}{\omega(D(\xi,1))}
\int\limits_{D(\xi,1)}e^{\frac{q\alpha}{2}|z|^{2}}d\mu(z)\biggr)^{\frac{p}{p-q}}\omega(\xi)dA(\xi)\biggr)^{\frac{p-q}{p}}\\
&\lesssim \epsilon+\epsilon\|f_{k}\|_{\Cal{F}_{\alpha,\omega}^{p}}\leqslant (1+M)\epsilon.
\endalign
$$
And hence, $D^{n}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow L^{q}(\mu)$ is compact, which finishes the proof.
\qed\enddemo
With the help of the above conclusion, we can now provide the proof of \Par*{Theorem 1}.
\demo{Proof of \Par*{Theorem 1}}
Note that the non-univalent %\?
change of variables formula indicates $\|D_{\varphi,u}^{n}f\|_{L_{\nu}^{q}}=\|f^{(n)}\|_{L_{\varphi_{*}(|u|^{q}\nu)}^{q}}$.
This together with \Par*{Theorem 10} ends the proof.
\qed\enddemo
The following theorem concerns the compactness of differentiation operator $D^{n}: \Cal{F}_{\alpha,\omega}^{p}\rightarrow L^{q}(\mu)$ with $0