\documentclass[reqno]{amsart}
\usepackage{hyperref}
\usepackage{graphicx}

\AtBeginDocument{{\noindent\small
\emph{Electronic Journal of Differential Equations},
Vol. 2011 (2011), No. 20, pp. 1--23.\newline
ISSN: 1072-6691. URL: http://ejde.math.txstate.edu or http://ejde.math.unt.edu
\newline ftp ejde.math.txstate.edu}
\thanks{\copyright 2011 Texas State University - San Marcos.}
\vspace{9mm}}

\begin{document}
\title[\hfilneg EJDE-2011/20\hfil A numerical based investigation]
{A numerically based investigation on the symmetry breaking
and asymptotic behavior of the ground states to the $p$-H\'enon
equation}

\author[X. Yao, J. Zhou\hfil EJDE-2011/20\hfilneg]
{Xudong Yao, Jianxin Zhou}  % in alphabetical order

\address{Xudong Yao \newline
Department of Mathematics,
Shanghai Normal University, Shanghai, 200234, China}
\email{xdyao@shnu.edu.cn}

\address{Jianxin Zhou \newline
Department of Mathematics, Texas A\&M University,
College Station, TX 77843, USA}
\email{jzhou@math.tamu.edu}

\thanks{Submitted November 27, 2009. Published February 7, 2011.}
\subjclass[2000]{58E05, 58E30, 35A40, 35J65}
\keywords{The $p$-H\'enon equation; ground state; symmetry breaking;
\hfill\break\indent peak breaking; asymptotic behavior}

\begin{abstract}
 The symmetry breaking phenomenon (SBP) to the H\'enon
 equation was first numerically observed in \cite{CNZ} and then
 theoretically verified on the unit ball $B_n$ in \cite{SWS}. Some
 results on the asymptotic behavior of the ground states to the
 H\'enon equation on $B_n$ are presented in
 \cite{BW1,BW2,SW}. \cite{SWS} further discussed SBP to
 the $p$-H\'enon equation and obtained some results with
 special value $p\le n$ on $B_n$. To inspire theoretical study on
 more general $p$, a series of numerical experiments to the
 $p$-H\'enon equation on a disk and a square are carried out
 in this paper. Numerical computations are made by the minimax method
 developed in \cite{YZ1,YZ3}. Then, SBP, a peak break
 phenomenon (PBP); i.e., a 1-peak solution, which is symmetric about
 two axes and two diagonal lines, breaks its peak from 1 to 4, and a
 1-peak positive non-ground state solution, which is only symmetric
 about one axis, on the square are numerically captured and
 visualized. The peak point and the peak height of the ground states
 are carefully calculated to study their asymptotic behavior. Several
 conjectures are made based on the numerical observations to
 stimulate theoretical analysis. Two of them are proved in this paper.
\end{abstract}

\maketitle
\numberwithin{equation}{section}
\newtheorem{theorem}{Theorem}[section]
\newtheorem{remark}[theorem]{Remark}
\newtheorem{corollary}[theorem]{Corollary}


\section{Introduction}

Consider the $p$-H\'enon equation, a quasi-linear elliptic
boundary value problem (BVP) of the form
\begin{equation}\label{eq0.1}
\Delta_p u+|x|^r |u|^{q-2}u=0,\quad
x\in\Omega,\; u\in W_0^{1,p}(\Omega),
\end{equation}
where $\Delta_p$ is the $p$-Laplacian operator defined by $\Delta_p
u=\operatorname{div}(|\nabla u|^{p-2}\nabla u)$ ($p>1$),
$\Omega\subset\mathbb{R}^n$ is a bounded open domain, $|x|$ is the
Euclidian norm of $x$, $p<q<p^*$ ($p^*$ is the Sobolev exponent) and
$r\ge 0$. The original H\'enon equation ($p=2$) was proposed
by French astronomer and mathematician Michel H\'enon
\cite{He} to improve a model by the Lane-Emden (-Fowler) equation
($p=2, r=0$) in astrophysics in study of stellar systems. The study
of the H\'enon equation has crossed several disciplinary
branches. Many interesting properties, such as solution multiplicity
and various structures, bifurcation, chaos, \dots , are explored. This
equation was modified in several different ways and becomes an
important model in the study of nonlinear dynamic systems. One of
the important modifications leads to the $p$-H\'enon equation
due to applications in physical fields, typically in
non-Newtonian/Darcian fluid flows or materials, where the shear
stress $\vec{\tau}$ and the velocity gradient $\nabla u$ of the
fluid are related in the manner $\vec{\tau}(x)=r(x)|\nabla
u|^{p-2}\nabla u$. When $p=2$, $\Delta_p=\Delta$ is the Laplacian
operator whose wide applications are well-known and typical in the
study of Newtonian/Darcian fluid/material. When $p\neq 2$, the
$p$-Laplacian operator has a variety of applications in physical
fields and theoretical study as well, such as in the study of
Non-Newtonian/Darcian fluid/material. For example, the
fluid/material is called pseudo plastic if $p<2$ and dilatant if
$p>2$. The $p$-Laplacian operator also appears in the study of flow
in a porous media $(p=3/2)$, nonlinear elasticity $(p>2)$
and glaciology $(p\in (1,4/3))$ \cite{Diaz}.

It is quite natural for researchers to carry out parallel study of
the $p$-H\'enon equation to the path of successful study of
the H\'enon equation. Since $u=0$ is always a trivial
solution to \eqref{eq0.1}, people are interested in knowing the
existence or non-existence of nontrivial solutions, the number of
solutions as well as their structures in terms of qualitative
properties such as the geometric, symmetric and nodal (peak)
properties in different energy levels.

Mathematically it is known that the H\'enon and the
$p$-H\'enon equation belong to two classes of partial
differential equations with different complexities. The former is of
semilinear elliptic BVP since its derivative term is linear and can
be handled in a Hilbert space setting. While the later is of
quasilinear elliptic BVP since its derivative term is nonlinear. It
has to be handled in a Banach space setting and thus much tougher to
analysis. Consequently the regularity of solutions to the
$p$-H\'enon equation is weaker. Due to its Banach space
setting, even numerically the $p$-H\'enon equation is much
more difficult to solve, see \cite{YZ1,YZ3,YZ4}.

Though great progress has been made still many important open
questions remain unsettled. For instance, as one of many significant
differences between $\Delta$ and $\Delta_p$, the authors numerically
showed in \cite{YZ4} that on a square the second eigenvalue of
$-\Delta_p$ splits from a double eigenvalue into two simple
eigenvalues when $p$ moves from $2$ to $\neq 2$. Such an interesting
difference has not yet been theoretically verified.

Symmetry is one of the important characteristics to understand
solution structures. When $p=2$ and $r=0$, the well-known
Gidas-Ni-Nirenberg \cite{B} theorem states that if $\Omega$ is the
unit ball in $\mathbb{R}^n$, then it implies that the positive
ground state of \eqref{eq0.1} is radial. When $p=2$ and $r>0$, the
equation \eqref{eq0.1} has an explicit dependence on $x$. Although
radial symmetry is still kept to \eqref{eq0.1}, the
Gidas-Ni-Nirenberg theorem cannot be applied and the radial positive
solution may give up its ground state to new radially asymmetric
positive solutions. Such a phenomenon is called a \emph{symmetry
breaking phenomenon} (SBP) and was first numerically observed in
\cite{CNZ}. It immediately draws attentions. Several researchers
have theoretically verified the existence of such phenomenon
\cite{SWS} and obtained results on asymptotic behavior of the
ground states \cite{BW1,BW2,SW} when $r\to\infty$ and
$p$, $q$ are fixed. Researchers have also tried to study SBP for the
$p$-H\'enon equation \eqref{eq0.1} ($p\neq 2$) on the unit
ball $\Omega=B_n$ in $\mathbb{R}^n$. But results are very limited to
the value of $p$. For example, Theorem 8.2 in \cite{SWS} shows that
if $n>p$ and $n\ge2$, then, for any $p<q<p^*$, SBP must occur when
$r$ exceeds certain number; in \cite{BW1,BW2,SW}, when
$p=2$, $q$ is fixed and $r\to\infty$, asymptotic behavior of the
ground states of (1.1) is discussed. As the results in the
literature are under the assumption $p=2$ or $p<n$, it is quite
natural to ask if SBP to \eqref{eq0.1} will take place when $p\neq
2$, in particular, when $n\le p$ ($p>2$ corresponds to dilatant
fluid/material) and to study asymptotic behavior of the ground
states when $p\neq2$. So far no theoretical answer is available.
When $p=2$, $r=0$ and $\Omega$ is a non-radial domain, the
Berestycki-Nirenberg theorem \cite{B}, a beautiful generalization
of the Gidas-Ni-Nirenberg theorem, says that if $\Omega$ is
symmetric about a hyperplane in $\mathbb{R}^n$, then the positive
ground state of \eqref{eq0.1} is also symmetric about the
hyperplane. Similar to the Gidas-Ni-Nirenberg theorem, the
Berestycki-Nirenberg theorem does not work to \eqref{eq0.1} with
$r>0$, although, to \eqref{eq0.1}, symmetry about any hyperplane
passing through the origin is still there. In other words, the
positive ground states may be asymmetric about a hyperplane passing
through the origin although the domain $\Omega$ is symmetric about
it. This phenomenon is also called SBP. On symmetry of the positive
ground states of \eqref{eq0.1} with $r>0$ on a non-radial domain
$\Omega$, \emph{little research is done}. As the first step, we would
like to investigate \eqref{eq0.1} on simple non-radial domains which
are symmetric about some hyperplanes passing through the origin to
see if the positive ground states have same symmetry or not. Among
these domains, the hypercubic domains $(-a,a)^n$, $a>0$, are good
candidates. They have simple structure and symmetry about every
coordinate hyperplane. Due to the form of \eqref{eq0.1}, if $u_1$ is
a solution on $(-a_1,a_1)^n$, $a_1>0$, then
$u_2(x)=ku_1(\frac{a_1}{a_2}x)$ is a solution on $(-a_2,a_2)^n$,
$a_2>0$, where $k=(\frac{a_1}{a_2})^{\frac{p+r}{q-p}}$. Hence, the
value of $a$ has no influence on symmetry. Similarly, the value of
radius has no influence on radial symmetry in the study of solutions
to \eqref{eq0.1} on a ball of center at the origin. In Theorem
\ref{thmz} and Theorem \ref{thmz2}, we will draw conclusions on
general domains about asymptotic behavior of the positive ground
states to \eqref{eq0.1} by observing numerical results on $B_2$ and
$(-1,1)^2$. So, in this paper, the minimax method developed by the
authors in \cite{YZ1,YZ3} is applied to carry out a series of
numerical investigations of the $p$-H\'enon equation on {\em
the disk $B_2$} and \emph{the square $(-1,1)^2$} about SBP and
asymptotic behavior of its positive ground states. Through numerical
computation and visualization, we try to figure out a possible
answer to stimulate further theoretical study.

The corresponding energy functional of \eqref{eq0.1} is
\begin{equation}\label{eq0.2}
J(u)=\int_{\Omega}\Big[\frac1p |\nabla u(x)|^p-\frac1q
|x|^r|u(x)|^q\Big]dx, \quad \forall u\in W_0^{1,p}(\Omega).
\end{equation}
Then, for each $v\in W_0^{1,p}(\Omega)$,
\begin{align*}
\langle \nabla J(u),v\rangle&= \frac{d}{ds} J(u+sv)\Big|_{s=0}\\
&= \int_{\Omega}\Big[ |\nabla u(x)|^{p-2}\nabla u(x)\cdot\nabla
v(x)-|x|^r|u(x)|^{q-2}u(x)v(x)\Big]dx\\
&= \int_\Omega\Big[ -\nabla(|\nabla u(x)|^{p-2}\nabla u(x))
v(x)-|x|^r|u(x)|^{q-2}u(x)v(x)\Big]dx\\
&= \int_\Omega\Big[-\Delta_p u(x)-|x|^r|u(x)|^{q-2}u(x)\Big]v(x)dx.
\end{align*}
Thus it is clear that weak solutions of \eqref{eq0.1} coincide with
critical points of $J$, i.e., $\nabla J(u)=0$. The first candidates
of critical points are the local extrema. Traditional calculus of
variation and numerical methods focus on finding such stable
solutions. As for $J$ in \eqref{eq0.2}, the only local extremum is
the local minimum, the trivial solution $u\equiv 0$. Critical points
that are not local extrema are unstable and called saddle points.
Numerically computing those saddle points in a stable way is very
challenging due to their instability and multiplicity. A numerical
minimax method is developed by the authors in \cite{YZ1} for
finding multiple saddle points in a Banach space following a
sequential order. Its convergence is established in \cite{YZ3}. By
this method, we could carry out efficient and reliable numerical
experiments on \eqref{eq0.1}. Since for $p>2$, the regularity of
solutions to \eqref{eq0.1} is weaker, for possible weak solutions
$u$, the peak height has to be defined by the essential supremum
(ess.$\,\sup$) of $|u|$ instead of maximum ($\max$) of $|u|$ and the
peak point is then defined to be the set of all points whose any
neighborhoods have the essential supremum of $|u|$ equal to the peak
height.

In our numerical experiments, the Sobolev norm $\|\nabla
J(u)\|<0.005$ is used to terminate an iteration in our local minimax
method. On both domains, SBP are found in our numerical experiments
when $r$ is large. The peak point and peak height of the ground
state are carefully calculated, which provides us with some
information on their asymptotic behavior as the parameter
$r\to+\infty$. Through our numerical computation on a square, we
captured a peak breaking phenomenon (PBP), i.e., the 1-peak positive
solution, which is symmetric about the lines $x=0$, $y=0$ and $y=\pm
x$, breaks its peak from one to four when $r$ increases and exceeds
a certain value; we also numerically found 1-peak non-ground state
solutions, which is only symmetric about the line $x=0$ or $y=0$, by
enforcing this symmetry in the computation. Finally we make some
mathematical analysis and conjectures based on our numerical
observations.

At the end of this section, we attach the flow chart of our
minimax algorithm for numerically finding multiple solutions of
$p$-Laplacian equation in \cite{YZ1,YZ3}. In Step 3, the
descent direction is calculated by $\nabla J$. This is a computing
technique developed by us \cite{YZ1,YZ3} for $p$-Laplacian
equation. Assume that $u_1,u_2,\dots ,u_{n-1}$ are found critical
points of $J\in C^1(W_0^{1,\bar p}(\Omega),\mathbb R)$,
$L=[u_1,u_2,\dots ,u_{n-1}]$, i.e., the subspace of $W_0^{1,\bar
p}(\Omega)$ spanned by $u_1,u_2,\dots ,u_{n-1}$, $\Omega\subset
\mathbb R^n$ is an open, bounded set and $\frac1{\bar p}
+\frac1{\bar q}=1$, $\bar p,\bar q>0$. We denote $\|\cdot\|_{\bar r}$
as $\|\cdot\|_{W_0^{1,\bar r}(\Omega)}$ for $\bar r>1$.
$\epsilon>0$ is a small number and $0<\lambda<1$ is a constant. The
following is the flow chart of the algorithm.
\begin{itemize}

\item[\textbf{Step 1:}] Let $v_n^1 \in S_{L^{\perp}}$.

\item[\textbf{Step 2:}] Set $k=1$ and solve for
\begin{align*} u_n^k&= P(v_n^k) = t_0^kv_n^k+t_1^ku_1+\dots+t_{n-1}^k
u_{n-1}\\
&= \arg\max\{ J(t_0v_n^k+t_1u_1+\dots+t_{n-1}u_{n-1})|t_i\in\mathbb
R, i=0,1,\dots ,n-1\}.
\end{align*}

\item [\textbf{Step 3:}] Find a descent direction $w_n^k
=-sign(t_0^k)\nabla J(u_n^k)$ at $u_n^k=P(v_n^k)$.

\item [\textbf{Step 4:}] If $\|\nabla J(u_n^k)\|_{\bar q}<\varepsilon$,
then output $u_n^k$, stop. Otherwise, do Step 5.

\item [\textbf{Step 5:}] For each $s>0$, let
$$
v_n^k(s)
=\frac{v_n^k+sw_n^k}{\|v_n^k+sw_n^k\|_{\bar p}}
$$
and use the initial point $(t_0^k, t_1^k, \dots  ,t_{n-1}^k)$ to solve for
\[
P(v_n^k(s))=\arg\max\Big\{
J(t_0v_n^k(s)+\sum_{i=1}^{n-1}t_iu_i)|t_i\in\mathbb R, i=0,1,\dots ,n-1
\Big\},
\]
then set $v_n^{k+1}=v_n^k(s_n^k)$ and
$u_n^{k+1}=P(v_n^{k+1})=t_0^{k+1}v_n^{k+1}+t_1^{k+1}u_1
+\dots+t_{n-1}^{k+1}u_{n-1}$, where $s_n^k$ satisfies
$$s_n^k=\max\{ s=\frac{\lambda}{2^m}|m \in N,
J(P(v_n^k(s)))-J(P(v_n^k))\le -\frac14|t_0^k|s\|\nabla
J(u_n^k)\|_2^2\}.$$

\item [\textbf{Step 6:}] Update $k=k+1$ and go to Step 3.
\end{itemize}

\begin{remark} \label{rmk1.1} \rm
As $1<\bar p<2$, we assume that $u_1,u_2,\dots ,u_{n-1}$ are nice;
i.e., $L\subset W_0^{1,\bar q}(\Omega)$ and $S_{L^{\perp}}=\{u\in
W_0^{1,\bar p}(\Omega)|\langle u,u_i\rangle=0,\;i=1,\dots ,n-1\;and
\;\|u\|_{\bar p}=1\}$ for $\bar p>1$ in the algorithm.
\end{remark}

\section{Numerical and Analytic Results}

\subsection{On the Unit Disk in $\mathbb{R}^2$}
Let us first consider the $p$-H\'enon equation \eqref{eq0.1}
on the unit ball $\Omega=B_n\subset{\mathbb R}^n$. Numerically we
choose the unit disk $\Omega=B_2\subset {\mathbb R}^2$. To maintain
sufficient accuracy, over $10^5$ triangle elements are used on $B_2$
in our numerical experiment. We will focus on computing ground
states to see if SBP occurs. By our computation, we notice that the
1-peak positive radial solution always exists. The contours of these
numerical radial solutions are presented in Fig.~\ref{fig1} and in 
(c) and (f) of Figs.~\ref{fig2}-\ref{fig5}. In the
computation to capture the ground state, we always use a positive
non-radial initial guess. If a numerical solution is radially
symmetric, then our numerical experiment does not support SBP. Thus
in (a) and (d) of Figs.~\ref{fig2}-\ref{fig5}, once a
contour plot of the radially symmetric numerical solution is
presented, it means that for the values of $p,q,r$, SBP does not
occur. Otherwise, the contours of a non-radial numerical solution
will be presented in (b) and (e) of
Figs.~\ref{fig2}-\ref{fig5}. By Figs.~\ref{fig4} and \ref{fig5}, it
can be concluded that SBP to \eqref{eq0.1} on the unit disk
$\Omega=B_2$ will take place when $r$ increases and exceeds a certain
number $r_b$ for $p=2.5, 3.0$. Since $2=n\le p=2.5, 3.0$, it is
reasonable to conjecture that SBP to \eqref{eq0.1} on the unit disk
$\Omega=B_2$ will take place when $r$ increases and exceed a certain
number $r_b$ for every $p>2$. On the other hand, as we mentioned
before, Theorem 8.2 in \cite{SWS} shows that if $n>p$ and $n\ge2$,
then, for any $p<q<p^*$, SBP must occur when $r$ increases and exceeds
a certain number $r_b$. Hence, indeed we conjecture that SBP to
\eqref{eq0.1} on the unit disk $\Omega=B_2$ will take place for
every $p\neq2$ when $r$ increases and exceeds  a certain number $r_b$.
Generally, we would like to conjecture that SBP to \eqref{eq0.1}
with $p\neq2$ on the unit ball $\Omega=B_n$ in $\mathbb{R}^n$ will
always occur when $r$ increases and exceeds  a certain number $r_b$. In
Table \ref{tab10}, we give information on the location of $r_b$
from our numerical experiment.

In Figures \ref{fig2}-\ref{fig5}, if we compare (a) with (c) and
(d) with (f), we can see that the top of the 1-peak radial solution
becomes flatter as $r$ increases. Next, we carry out more numerical
experiments to investigate asymptotic behavior of the peak point and
peak height to a positive ground state of \eqref{eq0.1} as
$r\to+\infty$. To $(p,q)=(a)(1.75,7.75)$, $(b)(1.75,9.25)$,
$(c)(2.0,8.0)$, $(d)(2.0,9.5)$, $(e) (2.5,8.5)$, $(e) (2.5,10.0)$,
$(g)(3.0,9.0)$, $(h)(3.0,10.5)$, we list our numerical results in
Tables \ref{tab1} and \ref{tab2}. From Table \ref{tab1}, it is
quit natural to conclude that the peak point $(\alpha(r),0)\to(1,0)$
as $r\to\infty$. From Table \ref{tab2}, we can see that the peak
height $\beta(r)$ is monotonously increasing in $r$ when $p$ and $q$
are fixed. Based on this numerical observation, we prove
$\lim_{r\to+\infty}\beta(r)=+\infty$.
\clearpage

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig1a}
\includegraphics[width=0.30\textwidth]{fig1b}
\includegraphics[width=0.30\textwidth]{fig1c}
\\ (a)\hfil (b) \hfil (c)\\
\includegraphics[width=0.30\textwidth]{fig1d}
\includegraphics[width=0.30\textwidth]{fig1e}
\includegraphics[width=0.30\textwidth]{fig1f}
\\ (d)\hfil (e) \hfil (f)
\end{center}
\caption{Ground states for $r=0$: From (a) to (f)
$(p,q)=(1.75,7.75)$, $(1.75,9.25)$, $(2.5,8.5)$,
$(2.5,10.0)$, $(3.0,9.0)$, $(3.0,10.5)$.}
\label{fig1}
\end{figure}

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig2a} %1c1
\includegraphics[width=0.30\textwidth]{fig2b} %2c1
\includegraphics[width=0.30\textwidth]{fig2c} %3c1
\\ (a)\hfil (b) \hfil (c)\\
\includegraphics[width=0.30\textwidth]{fig2d} %1c2
\includegraphics[width=0.30\textwidth]{fig2e} %2c2
\includegraphics[width=0.30\textwidth]{fig2f} %3c2
\\ (d)\hfil (e) \hfil (f)
\end{center}
\caption{$p=1.75$: (a) $q=7.75$, $r=0.001$; (b)(c) $q=7.75$,
$r=1.4$; (d) $q=9.25$, $r=0.001$; (e)(f) $q=9.25$, $r=1.4$.}
\label{fig2}
\end{figure}
\clearpage

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig3a} %1c3
\includegraphics[width=0.30\textwidth]{fig3b} %2c3
\includegraphics[width=0.30\textwidth]{fig3c} %3c3
\\ (a)\hfil (b) \hfil (c)\\
\includegraphics[width=0.30\textwidth]{fig3d} %1c4
\includegraphics[width=0.30\textwidth]{fig3e} %2c4
\includegraphics[width=0.30\textwidth]{fig3f} %3c4
\\ (d)\hfil (e) \hfil (f)
\end{center}
\caption{$p=2.0$: (a) $q=8.0$, $r=0.001$; (b)(c) $q=8.0$, $r=1.4$;
(d) $q=9.5$, $r=0.001$; (e)(f) $q=9.5$, $r=1.4$.}\label{fig3}
\end{figure}

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig4a} %1c5
\includegraphics[width=0.30\textwidth]{fig4b} %2c5
\includegraphics[width=0.30\textwidth]{fig4c} %3c5
\\ (a)\hfil (b) \hfil (c)\\
\includegraphics[width=0.30\textwidth]{fig4d} %1c6
\includegraphics[width=0.30\textwidth]{fig4e} %2c6
\includegraphics[width=0.30\textwidth]{fig4f} %3c6
\\ (d)\hfil (e) \hfil (f)
\end{center}
\caption{$p=2.5$: (a) $q=8.5$, $r=0.001$; (b)(c) $q=8.5$, $r=1.4$;
(d) $q=10.0$, $r=0.001$; (e)(f) $q=10.0$, $r=1.4$.}
 \label{fig4}
\end{figure}
\clearpage

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig5a} %1c7
\includegraphics[width=0.30\textwidth]{fig5b} %2c7
\includegraphics[width=0.30\textwidth]{fig5c} %3c7
\\ (a)\hfil (b) \hfil (c)\\
\includegraphics[width=0.30\textwidth]{fig5d} %1c8
\includegraphics[width=0.30\textwidth]{fig5e} %2c8
\includegraphics[width=0.30\textwidth]{fig5f} %3c8
\\ (d)\hfil (e) \hfil (f)
\end{center}
\caption{$p=3.0$: (a) $q=9.0$, $r=0.001$; (b)(c) $q=9.0$, $r=1.4$;
(d) $q=10.5$, $r=0.001$; (e)(f) $q=10.5$, $r=1.4$.} \label{fig5}
\end{figure}

\begin{table}[htb]
\caption{Values for $\alpha$ in Equation \eqref{eq0.1} with $(\alpha,0)$ as
peak point of its ground state and $(p,q)$: (a)(1.75,7.75),
(b)(1.75,9.25), (c)(2.0,8.0), (d)(2.0,9.5), (e)(2.5,8.5),
(f)(2.5,10.0), (g)(3.0,9.0), (h)(3.0,10.5)}\label{tab1}
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|c|c|c|}
\hline
r&(a)&(b)&(c)&(d)&(e)&(f)&(g)&(h)\\
\hline
1&0.5694&0.473&0.4563&0.4526&0.3238&0.3158&0.2567&0.2505\\
\hline
10&0.9100&0.9327&0.8475&0.8434&0.7389&0.7253&0.6673&0.6554\\
\hline
20&0.9469&0.9397&0.9125&0.9100&0.8382&0.8319&0.7862&0.7764\\
\hline
30&0.9585&0.9580&0.9366&0.9356&0.8880&0.8787&0.8444&0.8382\\
\hline
40&0.9667&0.9698&0.9523&0.9514&0.9097&0.9055&0.8772&0.8697\\
\hline
50&0.9780&0.9745&0.9605&0.9598&0.9253&0.9222&0.8974&0.8912\\
\hline
60&0.9812&0.9782&0.9651&0.9630&0.9356&0.9344&0.9113&0.9071\\
\hline
70&0.9815&0.9814&0.9682&0.9682&0.9461&0.9408&0.9249&0.9197\\
\hline
80&0.9846&0.9835&0.9741&0.9734&0.9503&0.9492&0.9312&0.9260\\
\hline
90&&&0.9757&0.9757&0.9576&0.9549&0.9385&0.9368\\
\hline
100&&&&&0.9603&0.9576&0.9447&0.9409\\
\hline 110&&&&&&&0.9489&0.9472\\
\hline
\end{tabular}
\end{center}
\end{table}
\clearpage
\begin{table}[htb]
\caption{Values for $\beta$ in Equation \eqref{eq0.1} with $\beta$ as peak
height of its ground state and $(p,q)$: (a)(1.75,7.75), (b)(1.75,9.25),
(c)(2.0,8.0), (d)(2.0,9.5), (e)(2.5,8.5), (f)(2.5,10.0),
(g)(3.0,9.0), (h)(3.0,10.5)}\label{tab2}
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|c|c|c|}
\hline
r&(a)&(b)&(c)&(d)&(e)&(f)&(g)&(h)\\
\hline
1&2.7014&2.6771&2.3321&2.1732&2.2658&2.0618&2.2963&2.0698\\
\hline
10&3.8074&3.6796&3.5306&3.0597&3.8002&3.1791&4.2536&3.4725\\
\hline
20&4.2279&4.0109&4.1718&3.5142&4.7398&3.8162&5.5682&4.3602\\
\hline
30&4.6128&4.2008&4.6094&3.8119&5.4016&4.2661&6.5753&4.9885\\
\hline
40&5.0197&4.2456&4.9304&4.0266&5.9826&4.6180&7.4031&5.5313\\
\hline
50&5.1745&4.4020&5.1998&4.2301&6.4534&4.9311&8.0722&5.9702\\
\hline
60&5.2685&4.4032&5.3939&4.3527&6.8090&5.1067&8.7009&6.3522\\
\hline
70&5.4229&4.5602&5.6626&4.4925&7.2276&5.3267&9.2710&6.6541\\
\hline
80&5.5110&4.6427&5.9859&4.5949&7.4819&5.5139&9.7939&6.9534\\
\hline
90&&&6.0895&4.6753&7.8675&5.7908&10.3577&7.3044\\
\hline
100&&&&&8.1275&5.9344&10.8145&7.5803\\
\hline
110&&&&&&&11.2683&7.8350\\
\hline
\end{tabular}
\end{center}
\end{table}

\begin{table}[htb]
\caption{$r_b\in(r_1,r_2)$ for $(p,q)$: (a)(1.75,7.75),
(b)(1.75,9.25), (c)(2.0,8.0), (d)(2.0,9.5), (e)(2.5,8.5),
(f)(2.5,10.0), (g)(3.0,9.0), (h)(3.0,10.5)}\label{tab10}
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|c|c|c|}
\hline
&(a)&(b)&(c)&(d)\\
\hline
$(r_1,r_2)$&(0.0027,0.0054)&(0.0012,0.0024)&(0.0245,0.0272)&(0.0082,0.0109)\\
\hline
&(e)&(f)&(g)&(h)\\
\hline
$(r_1,r_2)$&(0.0490,0.0531)&(0.0218,0.0245)&(0.1147,0.1530)&(0.0764,0.0792)\\
\hline
\end{tabular}
\end{center}
\end{table}

\begin{theorem}\label{thmz}
\[
h(r)\ge C(\frac{r+n}n)^{1/q}
\]
where
$h(r)=\inf\{\operatorname{ess.\,sup}_{x\in\Omega}|u(x)|$:
$u$ is a nontrivial solution to \eqref{eq0.1}on
$\Omega\subseteq B_n\}$,
$\Omega$ is an open set with Lipschitz boundary and $C>0$ is a
constant independent of $r$.
\end{theorem}

\begin{proof}
If $u$ is a nontrivial solution to \eqref{eq0.1} on
$\Omega$, we have
\[
-\int_{\Omega}|\nabla u|^pdx+\int_{\Omega}|x|^r|u|^qdx
=\int_{\Omega}(\Delta_p u+|x|^r|u|^{q-2}u)udx=0;
\]
i.e.,
\[
\int_{\Omega}|\nabla u|^pdx=\int_{\Omega}|x|^r|u|^qdx.
\]
Then, by the hyperspherical coordinates,
\begin{align*}
\int_{\Omega}|x|^r|u|^qdx
&=\int_{B_n}|x|^r|u_B|^qdx\\
&\leq (\operatorname{ess.\,sup}_{x\in \Omega}|u(x)|)^q \\
&\quad \times \int_0^1\rho^{r+n-1}d\rho\int_0^{2\pi}\int_{-\frac{\pi}2}
^{\frac{\pi}2}\dots\int_{-\frac{\pi}2}^{\frac{\pi}2} F(\phi,
\theta_1,\dots ,\theta_{n-2})d\phi d\theta_1\dots d\theta_{n-2}\\
&= (\operatorname{ess.\,sup}_{x\in \Omega}|u(x)|)^q\frac{nV_n}{r+n};
\end{align*}
i.e.,
\begin{equation}\label{eq.1001}
\operatorname{ess.\,sup}_{x\in\Omega}|u(x)|\ge(\frac{r+n}{nV_n})^{1/q}
(\int_{\Omega}|\nabla u|^pdx)^{1/q},
\end{equation}
where $F(\phi,\theta_1,\dots ,\theta_{n-2})=|det(J(\phi,
\theta_1,\dots ,\theta_{n-2}))|$, $J(\phi, \theta_1,\dots ,\theta_{n-2})$
is the Jacobian matrix to the coordinate system transformation
between the Cartesian coordinate system and the hyperspherical
coordinate system, $V_n$ is the volume of the unit ball $B_n$ and
\[
u_B(x)=\begin{cases}
         u(x),&x\in\Omega,\\
         0,&x\notin\Omega.
         \end{cases}
\]
On the other hand, by the Sobolev imbedding theorem,
\[
\int_{\Omega}|\nabla u|^pdx=\int_{\Omega}|x|^r|u|^q
dx\le\int_{\Omega}|u|^qdx\le c\Big(\int_{\Omega}|\nabla
u|^pdx\Big)^{q/p},
\]
i.e.,
\begin{equation}\label{eq.1002}
\int_{\Omega}|\nabla u|^pdx\ge c^{p/(p-q)},
\end{equation}
where $c>0$ is a constant independent of $r$. Thus, from
\eqref{eq.1001} and \eqref{eq.1002}, for every nontrivial solution
$u$ to \eqref{eq0.1} on $\Omega\subseteq B_n$,
\[
\operatorname{ess.\,sup}_{x\in\Omega}|u(x)|\ge(\frac{r+n}{nV_n})^{1/q}
c^{\frac{p}{q(p-q)}};
\]
i.e.,
\[
h(r)\ge C(\frac{r+n}n)^{1/q},
\]
where $C=c^{\frac{p}{q(p-q)}}V_n^{-\frac1q}$ is a constant
independent of $r$.
\end{proof}

\begin{corollary}
\[
\lim_{r\to+\infty}\beta(r)=+\infty.
\]
where $\;\beta(r)=\{\operatorname{ess.\,sup}_{x\in\Omega}|u(x)||u\;\mbox{is
the ground state to \eqref{eq0.1} on}\;\mbox{an open set}\;\Omega
\subseteq B_n\;\mbox{with Lipschitz boundary}.\}.$
\end{corollary}

\begin{remark}\label{rm1} \rm
(1) From the above proof, it is clear that we have actually proved
that the peak height of any nontrivial solution to $p$-H\'enon equation \eqref{eq0.1} on an open set $\Omega\subseteq B_n$ with
Lipschitz boundary goes to $+\infty$ as $r\to +\infty$.\\
(2) $\Omega=B_n$ is a special case.
\end{remark}




%\begin{table}[htb]
%\caption{Values for $\beta$ in Equation \eqref{eq0.1} with $\beta$ as peak

\subsection{On a Square Domain in $\mathbb{R}^2$}
Consider the $p$-H\'enon equation \eqref{eq0.1} on the
hypercubic domain $\Omega=(-1,1)^n$. Numerically, we set $n=2$. If a
solution of \eqref{eq0.1} is symmetric about the lines $x=0$, $y=0$
and $y=\pm x$, we say it is BN (Berestycki-Nirenberg) symmetric.
Until now, theoretically, little is known about SBP and asymptotic
behavior of its ground states. For numerical investigation, to
maintain sufficient accuracy, over $10^6$ square elements are used
on $\Omega=(-1,1)^2$ in our numerical computation. From many
numerical results we obtained, we notice that the $p$-H\'enon
equation \eqref{eq0.1} on a square has much richer breaking
phenomena than its counterpart on the unit disk due to the corner
affect. First we notice that the positive BN symmetric solution
always exists. On this solution, our numerical results for $r=0$
have been presented in \cite{YZ1} and the contours of our numerical
results for $r>0$ are presented in (c) and (e) of
Figs.~\ref{fig6}-\ref{fig13}. Due to the explicit dependence of the
equation on $x$, SBP may occur. In this case, the positive BN
symmetric solution gives up its ground state to some positive BN
asymmetric solutions. It causes (1) SBP and (2) a peak breaking
phenomenon (PBP), more specifically, when $r$ increases and exceeds  a
certain value, the 1-peak BN symmetric positive solution becomes the
4-peak BN symmetric positive solution.

To investigate (1), SBP, we always use a BN asymmetric initial guess
to start with the algorithm for capturing the ground state. If the
numerically captured solution is BN symmetric, then our numerical
experiment does not support SBP. In this case, we put the contours
of BN symmetric numerical solutions in (a) of
Figs.~\ref{fig6}-\ref{fig13} as the contours of the ground states.
Otherwise, the contours of BN asymmetric numerical solutions are
presented in (b) and (d) of Figs.~\ref{fig6}-\ref{fig13} as
the contours of the ground states. The corresponding BN symmetric
positive solution has higher energy level. Our minimax method is
used to capture it. The contours of the BN symmetric numerical
solutions are listed in (c) and (e) of
Figs.~\ref{fig6}-\ref{fig13}. By our numerical results, we conclude
that to the $p$-H\'enon equation \eqref{eq0.1} on $(-1,1)^2$,
SBP always takes place when $r$ increases and exceeds  a certain value
$r_{b_1}$. By (b) and (d), when SBP occurs, the BN asymmetric
ground state is only symmetric about the line $y=x$ or $y=-x$
passing through the peak point. Generally, we would like to
conjecture that to the $p$-H\'enon equation \eqref{eq0.1} on
the hypercubic domain $(-1,1)^n$, SBP always occurs when $r$
increases and exceeds  a certain value $r_{b_1}$. In Table \ref{tab11},
we give information on the location of $r_{b_1}$ from our numerical
experiment. By (c) and (e), when $r$ increases and exceeds  a
certain value $r_{b_2}$, the 1-peak BN symmetric positive solution
in (c) becomes the 4-peak BN symmetric positive solution in (e),
i.e., (2), PBP, takes place. In Table \ref{tab12}, we give
information on the location of $r_{b_2}$ from our numerical
experiment.

Similar to the disk domain, more numerical experiments are carried
out to investigate asymptotic behavior of the peak point and peak
height of the positive ground state to (1.1) as $r\to+\infty$. For
$(p,q)=(a)(1.75,4.75)$, $(b)(1.75,6.25)$, $(c)(2.0,5.0)$,
$(d)(2.0,6.5)$, $(e)(2.5,5.5)$, $(f)(2.5,7.0)$, $(g)(3.0,6.0)$,
$(h)(3.0,7.5)$, our numerical results on the peak points and peak
heights are listed in Tables \ref{tab23} and \ref{tab24}. From
Table \ref{tab23}, it is quite natural to conclude that the peak
point is of the form $(\alpha(r),\alpha(r))$ and $\alpha(r)\to 1$ as
$r\to\infty$. Since the peak heights $\beta(r)$ listed in Table
\ref{tab24} are not monotone in $r$, we plot those $\beta(r)$
values in Fig.~\ref{fig14} from which one can see that for the
ground states to the $p$-H\'enon equation \eqref{eq0.1} on
the square domain $(-1,1)^2$, their peak heights, $\beta(r)\to 0$ as
$r\to\infty$.

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig6a} %conjectures2_c
\includegraphics[width=0.30\textwidth]{fig6b} %conjectures14_c
\includegraphics[width=0.30\textwidth]{fig6c} %conjectures6_c
\\ (a) \hfil (b) \hfil (c) \\
\includegraphics[width=0.30\textwidth]{fig6d} %conjectures18_c
\includegraphics[width=0.30\textwidth]{fig6e} %conjectures10_c
\\ (d) \hfil (e)
\end{center}
\caption{ $p=1.75$, $q=4.75$:
(a) $r=0.01$;
(b) $r=1.0$, a ground state;
(c) a 1-peak BN symmetric solution;
(d) $r=4.6$, a ground state;
(e) a 4-peak BN symmetric solution} \label{fig6}
\end{figure}

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig7a} %conjectures1_c
\includegraphics[width=0.30\textwidth]{fig7b} %conjectures13_c
\includegraphics[width=0.30\textwidth]{fig7c} %conjectures5_c
\\ (a) \hfil (b) \hfil (c) \\
\includegraphics[width=0.30\textwidth]{fig7d} %conjectures17_c
\includegraphics[width=0.30\textwidth]{fig7e} %conjectures9_c
\\ (d) \hfil (e)
\end{center}
\caption{$p=2.0$, $q=5.0$:
(a) $r=0.01$;
(b) $r=1.0$, a ground state;
(c) a 1-peak BN symmetric solution;
(d) $r=5.0$, a ground state;
(e) a 4-peak BN symmetric solution} \label{fig7}
\end{figure}
\clearpage

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig8a} %conjectures3_c
\includegraphics[width=0.30\textwidth]{fig8b} %conjectures15_c
\includegraphics[width=0.30\textwidth]{fig8c} %conjectures7_c
\\ (a) \hfil (b) \hfil (c) \\
\includegraphics[width=0.30\textwidth]{fig8d} %conjectures19_c
\includegraphics[width=0.30\textwidth]{fig8e} %conjectures11_c
\\ (d) \hfil (e)
\end{center}
\caption{$p=2.5$, $q=5.5$:
(a) $r=0.01$;
(b) $r=1.0$, a ground state;
(c) a 1-peak BN symmetric solution;
(d) $r=5.0$, a ground state;
(e) a 4-peak BN symmetric solution} \label{fig8}
\end{figure}

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig9a} %conjectures4_c
\includegraphics[width=0.30\textwidth]{fig9b} %conjectures16_c
\includegraphics[width=0.30\textwidth]{fig9c} %conjectures8_c
\\ (a) \hfil (b) \hfil (c) \\
\includegraphics[width=0.30\textwidth]{fig9d} %conjectures20_c
\includegraphics[width=0.30\textwidth]{fig9e} %conjectures12_c
\\ (d) \hfil (e)
\end{center}
\caption{$p=3.0$, $q=6.0$:
(a) $r=0.01$;
(b) $r=1.0$, a ground state;
(c) a 1-peak BN symmetric solution;
(d) $r=5.3$, a ground state;
(e) a 4-peak BN symmetric solution} \label{fig9}
\end{figure}
\clearpage

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig10a} %conjectures22_c
\includegraphics[width=0.30\textwidth]{fig10b} %conjectures34_c
\includegraphics[width=0.30\textwidth]{fig10c} %conjectures26_c
\\ (a) \hfil (b) \hfil (c) \\
\includegraphics[width=0.30\textwidth]{fig10d} %conjectures38_c
\includegraphics[width=0.30\textwidth]{fig10e} %conjectures30_c
\\ (d) \hfil (e)
\end{center}
\caption{$p=1.75$, $q=6.25$:
(a) $r=0.01$;
(b) $r=1.0$, a ground state;
(c) a 1-peak BN symmetric solution;
(d) $r=4.6$, a ground state;
(e) a 4-peak BN symmetric solution}
\label{fig10}
\end{figure}

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig11a} %conjectures21_c
\includegraphics[width=0.30\textwidth]{fig11b} %conjectures23_c
\includegraphics[width=0.30\textwidth]{fig11c} %conjectures25_c
\\ (a) \hfil (b) \hfil (c) \\
\includegraphics[width=0.30\textwidth]{fig11d} %conjectures37_c
\includegraphics[width=0.30\textwidth]{fig11e} %conjectures29_c
\\ (d) \hfil (e)
\end{center}
\caption{$p=2.0$, $q=6.5$:
(a) $r=0.01$;
(b) $r=1.0$, a ground state;
(c) a 1-peak BN symmetric solution;
(d) $r=5.0$, a ground state;
(e) a 4-peak BN symmetric solution}
\label{fig11}
\end{figure}
\clearpage

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig12a} %conjectures23_c
\includegraphics[width=0.30\textwidth]{fig12b} %conjectures35_c
\includegraphics[width=0.30\textwidth]{fig12c} %conjectures27_c
\\ (a) \hfil (b) \hfil (c) \\
\includegraphics[width=0.30\textwidth]{fig12d} %conjectures39_c
\includegraphics[width=0.30\textwidth]{fig12e} %conjectures31_c
\\ (d) \hfil (e)
\end{center}
\caption{$p=2.5$, $q=7.0$:
(a) $r=0.01$;
(b) $r=1.0$, a ground state;
(c) a 1-peak BN symmetric solution;
(d) $r=5.0$, a ground state;
(e) a 4-peak BN symmetric solution}
\label{fig12}
\end{figure}

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.30\textwidth]{fig13a} %conjectures24_c
\includegraphics[width=0.30\textwidth]{fig13b} %conjectures36_c
\includegraphics[width=0.30\textwidth]{fig13c} %conjectures28_c
\\ (a) \hfil (b) \hfil (c) \\
\includegraphics[width=0.30\textwidth]{fig13d} %conjectures40_c
\includegraphics[width=0.30\textwidth]{fig13e} %conjectures32_c
\\ (d) \hfil (e)
\end{center}
\caption{$p=3.0$, $q=7.5$:
(a) $r=0.01$;
(b) $r=1.0$, a ground state;
(c) a 1-peak BN symmetric solution;
(d) $r=5.3$, a ground state;
(e) a 4-peak BN symmetric solution}
\label{fig13}
\end{figure}
\clearpage

\begin{table}[htb]
\caption{Values for $\alpha$ in Equation \eqref{eq0.1} with $(\alpha,\alpha)$
as peak point of its ground state and $(p,q)$: (a) (1.75,4.75),
(b) (1.75,6.25), (c) (2.0,5.0), (d) (2.0,6.5), (e) (2.5,5.5),
(f) (2.5,7.0), (g) (3.0,6.0), (h) (3.0,7.5)}\label{tab23}
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|c|c|c|}
\hline
r&(a)&(b)&(c)&(d)&(e)&(f)&(g)&(h)\\
\hline
1&0.473&0.486&0.374&0.386&0.259&0.273&0.190&0.210\\
\hline
10&0.887&0.905&0.833&0.831&0.758&0.743&0.700&0.679\\
\hline
20&0.938&0.951&0.909&0.908&0.862&0.852&0.824&0.809\\
\hline
30&0.958&0.967&0.936&0.937&0.903&0.896&0.876&0.865\\
\hline
40&0.965&0.975&0.952&0.952&0.926&0.919&0.914&0.895\\
\hline
50&0.971&0.982&0.961&0.961&0.940&0.935&0.922&0.914\\
\hline
60&0.976&0.987&0.967&0.967&0.950&0.945&0.934&0.927\\
\hline
70&0.982&0.991&0.972&0.972&0.957&0.952&0.943&0.937\\
\hline
80&0.984&0.993&0.975&0.974&0.962&0.958&0.950&0.944\\
\hline
\end{tabular}
\end{center}
\end{table}

\begin{table}[htb]
\caption{Values for $\beta$ in Equation \eqref{eq0.1} with
$\beta$ as peak height of its ground state and
$(p,q)$: (a) (1.75,4.75), (b) (1.75,6.25), (c) (2.0,5.0),
(d) (2.0,6.5), (e) (2.5,5.5), (f) (2.5,7.0), (g) (3.0,6.0),
(h) (3.0,7.5)}\label{tab24}
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|c|c|c|}
\hline
r&(a)&(b)&(c)&(d)&(e)&(f)&(g)&(h)\\
\hline
1&3.6277&2.8676&3.6791&2.7576&3.9439&2.8144&4.2204&2.9194\\
\hline
10&3.6149&2.9320&4.0596&2.9330&5.4975&3.5136&7.3453&4.2542\\
\hline
20&1.6608&1.7568&1.9677&1.8104&2.9495&2.3255&4.3500&3.0147\\
\hline
30&0.6560&0.9509&0.8034&0.9964&1.2828&1.3361&2.0116&1.8052\\
\hline
40&0.2510&0.4869&0.3050&0.5269&0.5091&0.7234&0.8359&1.0066\\
\hline
50&0.0861&0.2421&0.1111&0.2666&0.1920&0.3773&0.3269&0.5392\\
\hline
60&0.0301&0.1250&0.0395&0.1338&0.0704&0.1929&0.1230&0.2807\\
\hline
70&0.0105&0.0659&0.0138&0.0663&0.0252&0.0972&0.0451&0.1441\\
\hline
80&0.0036&0.0348&0.0048&0.0325&0.0089&0.0485&0.0162&0.0728\\
\hline
\end{tabular}
\end{center}
\end{table}

\begin{table}[htb]
\caption{$r_{b_1}\in(r_1,r_2)$ for $(p,q)$: (a) (1.75,4.75),
(b) (1.75,6.25), (c) (2.0,5.0), (d) (2.0,6.5), (e) (2.5,5.5),
(f) (2.5,7.0), (g) (3.0,6.0), (h) (3.0,7.5)}\label{tab11}
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|c|c|c|}
\hline
&(a)&(b)&(c)&(d)\\
\hline
$(r_1,r_2)$&(0.1055,0.1094)&(0.0313,0.0352)&(0.1406,0.1445)&(0.1012,0.1058)\\
\hline
&(e)&(f)&(g)&(h)\\
\hline
$(r_1,r_2)$&(0.3006,0.3046)&(0.1367,0.1406)&(0.4572,0.461)&(0.2376,0.2411)\\
\hline
\end{tabular}
\end{center}
\end{table}
\clearpage

\begin{table}[htb]
 \caption{$r_{b_2}\in(r_1,r_2)$ for
$(p,q)=(a)(1.75,4.75)$, $(b)(1.75,6.25)$, $(c)(2.0,5.0)$,
$(d)(2.0,6.5)$, $(e)(2.5,5.5)$, $(f)(2.5,7.0)$, $(g)(3.0,6.0)$,
$(h)(3.0,7.5)$}\label{tab12}
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|c|c|c|}
\hline
&(a)&(b)&(c)&(d)\\
\hline
$(r_1,r_2)$&(1.7461,1.75)&(2.2461,2.25)&(1.7695,1.7734)&(3.3789,3.3828)\\
\hline
&(e)&(f)&(g)&(h)\\
\hline
$(r_1,r_2)$&(3.3867,3.3906)&(3.707,3.7109)&(3.4375,3.4399)&(3.8125,3.8164)\\
\hline
\end{tabular}
\end{center}
\end{table}

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.8\textwidth]{fig14} % tab4
\end{center}
\caption{$\beta(r)$ curves for $(p,q)$: (a) (1.75,4.75),
(b) (1.75,6.25), (c) (2.0,5.0), (d) (2.0,6.5), (e)(2.5,5.5),
(f) (2.5,7.0), (g) (3.0,6.0), (h) (3.0,7.5) in $r$-$\beta$
coordinate system. All $\beta(r)$ curves approach zero as
$r\to +\infty$}
\label{fig14}
\end{figure}

\begin{theorem}\label{thmz2}
Assume  the bounded open domain $\Omega\subset\mathbb R^n$
satisfies $max_{x\in\Omega}|x|>1$ where
$|x|=(\sum_{k=1}^nx_k^2)^{\frac12}$ and $r>0$, $1<p<q<p^*$ in
\eqref{eq0.1}. If $u^*_r$ is a ground state of \eqref{eq0.1}, then
$u^*_r\to 0$ as $r\to \infty$.
\end{theorem}

\begin{proof}
We have
\begin{equation}\label{eqZ1.1}
J(u)=\int_{\Omega}\Big[\frac1p |\nabla
u(x)|^p-\frac{|x|^r}{q}|u(x)|^q\Big]dx.
\end{equation}
First by our minimax characterization of solutions in \cite{YZ1},
for each fixed $r>0$ and each $v_r\in W_0^{1,p}(\Omega)$ with
$\|v_r\|=\int_{\Omega}|\nabla v_r(x)|^pdx=1$, $p(v_r)=t_rv_r$ where
$t_r=\arg \frac{d}{dt}J(tv_r)=0$ or
\begin{equation}\label{eqZ1.5}
t_r=(\int_{\Omega} |x|^r|v_r(x)|^q dx)^{\frac1{p-q}}.
\end{equation}
Since we have $\hat u_r=p(\hat v_r)=\hat t_r\hat v_r$ for every
nontrivial solution $\hat u_r$ of \eqref{eq0.1} where $\hat
v_r(x)=\frac{\hat u_r(x)}{\|\hat u_r\|}$ and
\[
\hat t_r=\|\hat u_r\|=(\int_{\Omega} |x|^r|\hat v_r(x)|^q
dx)^{\frac1{p-q}},
\]
a ground state is of the form $u^*_r=p(v^*_r)$ where
\begin{equation}\label{eqZ1.7}
v^*_r=\arg\min_{v_r\in W_0^{1,p}(\Omega),\|v_r\|=1}J(p(v_r)).
\end{equation}
By plugging $t_r$ in \eqref{eqZ1.5} into $J(t_rv_r)$ in
\eqref{eqZ1.1}, we obtain
\begin{equation}\label{eqZ1.6}
\begin{aligned}
J(t_rv_r)
&=\frac{t_r^p}{p}-\frac{t_r^q}{q}\int_{\Omega}
|x|^r|v_r(x)|^q\,dx=t_r^p(\frac1p-\frac1q)\\
&=\left[\int_{\Omega}|x|^r|v_r(x)|^q\,dx\right]^{p/(p-q)}
(\frac1p-\frac1q).
\end{aligned}
\end{equation}

Thus $u^*_r=p(v^*_r)=t^*_rv^*_r$ where $v^*_r\in W_0^{1,p}(\Omega)$
with $\|v^*_r\|=1$ and
\begin{equation}\label{eqZ1.2}
t_r^{*(p-q)}=\int_{\Omega} |x|^r|v^*_r(x)|^q dx.
\end{equation}
Since the bounded open domain $\Omega$ satisfies
$max_{x\in\Omega}|x|>1$, there exists $\bar x\in\Omega$ such that the
ball of center at $\bar x=(\bar x_1,\dots ,\bar x_n)$ and radius $\bar
r>0$, $B(\bar x,\bar r)\subset\Omega\setminus B_n$. Let
\[
\bar{v}(x)=\begin{cases}
(\bar r^2-\sum_{k=1}^n(x_k-\bar x_k)^2)^2,
  &x=(x_1,\dots ,x_n)\in B(\bar x,\bar r),\\
0,&x=(x_1,\dots ,x_n)\in \Omega\setminus B(\bar x,\bar r).
 \end{cases}
\]
Denote
$$
I(r)=\int_{\Omega\setminus B_n}|x|^rc_0^q|\bar{v}(x)|^qdx\to
+\infty\quad\mbox{as}\; r\to +\infty,
$$
where
$c_0=\|\bar{v}\|^{-1}$. By \eqref{eqZ1.7} for each fixed $r>0$, we
have
\begin{align*}
J(t^*_r v^*_r)
&=\Big[\int_{\Omega}|x|^r|v^*_r(x)|^q\,dx
\Big]^{p/(p-q)} (\frac1p-\frac1q)\le J(p(v))\\
&= \Big[\int_{\Omega}|x|^r|v(x)|^q\,dx\Big]^{p/(p-q)}
(\frac1p-\frac1q)
\end{align*}
for any $v\in W_0^{1,p}(\Omega)$ with $\|v\|=1$.
In particular, if we note $1<p<q$, we have
\begin{align*}
J(t^*_r v^*_r)
&=t^{*p}_r(\frac1p-\frac1q)\\
&\leq \Big[ \int_{\Omega}|x|^rc_0^q|\bar{v}(x)|^qdx\Big]^{p/(p-q)}
(\frac1p-\frac1q)\le I(r)^{p/(p-q)}(\frac1p-\frac1q)\to 0.
\end{align*}
Thus $t^*_r\to 0$; i.e., $u^*_r=t^*_rv^*_r\to 0$ as $r\to +\infty$
since $\|v^*_r\|=1$.
\end{proof}

\begin{remark}\label{rm2}
(1) By Remark \ref{rm1}, to the peak height $\beta_a(r)$ of the
ground states of \eqref{eq0.1} on $\Omega=(-a,a)^n$,
$a\le\frac1{\sqrt n}$, we have
\[
\lim_{r\to\infty}\beta_a(r)=+\infty.
\]

(2) To the ground states $u_a(r)$ of \eqref{eq0.1} on
$\Omega=(-a,a)^n$, $a>\frac1{\sqrt n}$, we have
\[
\lim_{r\to\infty}u_a(r)=0.
\]
$\Omega=(-1,1)^n$ is a special case.

(3) The conclusion $u(r)\to 0$ in the theorem is a little different
from $\beta(r)\to 0$ suggested by Table 4. On any bounded open
domain $\Omega\subset\mathbb R^n$ with
$max_{x\in\Omega}|x|=(\sum_{k=1}^nx_k^2)^{\frac12}>1$, we would like
to conjecture
\[
\beta(r)\to 0,
\]
where $\beta(r)$ is the peak height of the ground states of
\eqref{eq0.1}.
\end{remark}

\subsection{More on 1-peak BN asymmetric positive solutions}

In the last subsection, our numerical results suggest that to the
$p$-H\'enon equation \eqref{eq0.1} on the square domain
$\Omega=(-1,1)^2$, when SBP occurs, the BN asymmetric ground states
are only symmetric about the line $y=x$ or $y=-x$ passing through
the peak point. Then, it is interesting to ask if there exist 1-peak
BN asymmetric positive solutions which are symmetric about $x=0$ or
$y=0$.

Such a solution was numerically captured first by accident then on
purpose by enforcing an even-symmetry about the x-axis.
By the symmetry of the $p$-H\'enon equation on the square, it
is clear that there are actually four such solutions. According to
our numerical computation, such a solution has higher energy than
the ground state. So they are more unstable than the ground states.
In Figs.~\ref{fig15}-\ref{fig18}, the contours of numerical
results for such solutions are listed in the second row; the
contours of numerical results for ground states are displayed in the
first row; corresponding solution energies $J$ and $p,q,r$ values
are given in the captions.

We also did numerical experiments to investigate \eqref{eq0.1} on
$\Omega=(-1,1)$, a two-point boundary value problem. The profiles of
these numerical results are presented in the third row of Figs.
\ref{fig15}-\ref{fig18} with associated $p,q,r$ values in the
captions.

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.22\textwidth]{fig15a1} %conjectures14_c
\includegraphics[width=0.22\textwidth]{fig15b1} %conjectures13_c
\includegraphics[width=0.22\textwidth]{fig15c1} %conjectures15_c
\includegraphics[width=0.22\textwidth]{fig15d1} %conjectures16_c
\\
\includegraphics[width=0.22\textwidth]{fig15a2} %conjectures100_c
\includegraphics[width=0.22\textwidth]{fig15b2} %conjectures102_c
\includegraphics[width=0.22\textwidth]{fig15c2} %conjectures104_c
\includegraphics[width=0.22\textwidth]{fig15d2} %conjectures106_c
\\
\includegraphics[width=0.22\textwidth]{fig15a3} %1d1
\includegraphics[width=0.22\textwidth]{fig15b3} %1d2
\includegraphics[width=0.22\textwidth]{fig15c3} %1d3
\includegraphics[width=0.22\textwidth]{fig15d3} %1d4
\\
(a)\hfil (b) \hfil (c) \hfil (d)
\end{center}
\caption{$r=1.0$:
(a) $p=1.75$, $q=3.75$, $J=9.30, 9.92$;
(b) $p=2.0$, $q=4.0$, $J=12.31, 12.84$;
(c) $p=2.5$, $q=4.5$, $J=21.70, 22.10$;
(d) $p=3.0$, $q=5.0$, $J=40.38, 40.71$} \label{fig15}
\end{figure}
\clearpage

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.22\textwidth]{fig16a1} %conjecture116_c
\includegraphics[width=0.22\textwidth]{fig16b1} %conjecture117_c
\includegraphics[width=0.22\textwidth]{fig16c1} %conjecture118_c
\includegraphics[width=0.22\textwidth]{fig16d1} %conjecture119_c
\\
\includegraphics[width=0.22\textwidth]{fig16a2} %conjecture108_c
\includegraphics[width=0.22\textwidth]{fig16b2} %conjecture110_c
\includegraphics[width=0.22\textwidth]{fig16c2} %conjecture112_c
\includegraphics[width=0.22\textwidth]{fig16d2} %conjecture114_c
\\
\includegraphics[width=0.22\textwidth]{fig16a3} %1d5
\includegraphics[width=0.22\textwidth]{fig16b3} %1d6
\includegraphics[width=0.22\textwidth]{fig16c3} %1d7
\includegraphics[width=0.22\textwidth]{fig16d3} %1d8
\\
(a)\hfil (b) \hfil (c) \hfil (d)
\end{center}
\caption{
(a) $p=1.75$, $q=3.75$, $r=2.0$, $J=10.91, 13.47$;
(b) $p=2.0$, $q=4.0$, $r=3.0$, $J=19.44, 27.40$;
(c) $p=2.5$, $q=4.5$, $r=3.0$, $J=54.97, 73.31$;
(d) $p=3.0$, $q=5.0$, $r=2.0$, $J=94.63, 103.86$}
\label{fig16}
\end{figure}

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.22\textwidth]{fig17a1} %conjecture216_c
\includegraphics[width=0.22\textwidth]{fig17b1} %conjecture217_c
\includegraphics[width=0.22\textwidth]{fig17c1} %conjecture218_c
\includegraphics[width=0.22\textwidth]{fig17d1} %conjecture219_c
\\
\includegraphics[width=0.22\textwidth]{fig17a2} %conjecture200_c
\includegraphics[width=0.22\textwidth]{fig17b2} %conjecture202_c
\includegraphics[width=0.22\textwidth]{fig17c2} %conjecture204_c
\includegraphics[width=0.22\textwidth]{fig17d2} %conjecture206_c
\\
\includegraphics[width=0.22\textwidth]{fig17a3} %1d9
\includegraphics[width=0.22\textwidth]{fig17b3} %1d10
\includegraphics[width=0.22\textwidth]{fig17c3} %1d11
\includegraphics[width=0.22\textwidth]{fig17d3} %1d12
\\
(a)\hfil (b) \hfil (c) \hfil (d)
\end{center}
\caption{$r=1.0$:
(a) $p=1.75$, $q=4.75$, $J=6.25, 6.62$;
(b) $p=2.0$, $q=5.0$, $J=7.84, 8.16$;
(c) $p=2.5$, $q=5.5$, $J=11.88, 12.15$;
(d) $p=3.0$, $q=6.0$, $J=18.61, 18.86$}
\label{fig17}
\end{figure}
\clearpage

\begin{figure}[htb]
\begin{center}
\includegraphics[width=0.22\textwidth]{fig18a1} %conjecture220_c
\includegraphics[width=0.22\textwidth]{fig18b1} %conjecture221_c
\includegraphics[width=0.22\textwidth]{fig18c1} %conjecture222_c
\includegraphics[width=0.22\textwidth]{fig18d1} %conjecture223_c
\\
\includegraphics[width=0.22\textwidth]{fig18a2} %conjecture208_c
\includegraphics[width=0.22\textwidth]{fig18b2} %conjecture210_c
\includegraphics[width=0.22\textwidth]{fig18c2} %conjecture212_c
\includegraphics[width=0.22\textwidth]{fig18d2} %conjecture214_c
\\
\includegraphics[width=0.22\textwidth]{fig18a3} %1d13
\includegraphics[width=0.22\textwidth]{fig18b3} %1d14
\includegraphics[width=0.22\textwidth]{fig18c3} %1d15
\includegraphics[width=0.22\textwidth]{fig18d3} %1d16
\\
(a)\hfil (b) \hfil (c) \hfil (d)
\end{center}
\caption{(a) $p=1.75$, $q=4.75$, $r=2.0$, $J=6.91, 8.21$;
(b) $p=2.0$, $q=5.0$, $r=3.0$, $J=11.01, 14.43$;
(c) $p=2.5$, $q=5.5$, $r=3.0$, $J=24.48, 30.96$;
(d) $p=3.0$, $q=6.0$, $r=2.0$, $J=35.85, 39.17$}
\label{fig18}
\end{figure}

\section{Conclusions and Conjectures}

Many numerical experiments are carried out for 1-peak positive
solutions to the $p$-H\'enon equation \eqref{eq0.1} on the
unit disk $B_2$ and the square $\Omega_2=(-1,1)^2$. From our
numerical results and Theorem \ref{thmz}, for fixed $1<p<q<p^*$, we
have the following conclusions.

Conclusion I. As a bifurcation phenomenon, SBP always occurs when
$r$ increases and exceeds  a certain value, on both $B_2$ and $\Omega_2$.
When SBP takes place, the ground states are 1-peak solutions on
$B_2$ and 1-peak solutions with peak point $(a_1,a_2)$, where
$|a_1|=|a_2|>0$, on $\Omega_2$.

Conclusion II. On $B_2$, the peak point of the ground state goes to
the boundary of $B_2$ and its peak height tends to $+\infty$ as
$r\to+\infty$. On the other hand, the top of the 1-peak radially
symmetric solution becomes flatter as $r$ increases and its peak
height tends to $+\infty$ as $r\to +\infty$.

Conclusion III. On $\Omega_2$, when SBP occurs, 1-peak BN asymmetric
ground state is only symmetric about the line $y=x$ or $y=-x$
passing through its peak point. The peak point of the ground state
goes to a corner of $\Omega_2$ and its peak height tends to $0$ as
$r\to+\infty$. When $r$ increases and exceeds  a certain value, PBP takes
place, i.e., the 1-peak BN symmetric solution becomes a 4-peak BN
symmetric solution. Clearly PBP is not a bifurcation phenomenon
since the old solution is only replaced by a new solution.

Conclusion IV. On $\Omega_2$, when $r$ increased, there is 1-peak,
BN asymmetric, non-ground state, positive solution with its peak
point $(x_p,0)$, $x_p>0$ or $(0,y_p)$, $y_p>0$ which is symmetric
about the line $y=0$ or $x=0$.

Based on our numerical results which are still unique in the
literature, Theorem \ref{thmz} and Theorem \ref{thmz2}, for each
fixed $1<p<q<p^*$, we have the following conclusions and conjectures
for the $p$-H\'enon equation \eqref{eq0.1} in $\mathbb R^n$.
On the hypercubic domain $\Omega_n=(-1,1)^n$, if $\Omega_n$ is
symmetric about a hyperplane passing through the origin, then a
solution is also symmetric about it. We say such a solution is a BN
symmetric solution.

Conclusion I. On any bounded open set $\Omega\subseteq B_n$ with
Lipschitz boundary, the peak height of the solutions is proved in
Theorem~\ref{thmz} to tend to $+\infty$ as $r\to +\infty$.

Conclusion II.
On any bounded open domain $\Omega\subset\mathbb R^n$ with
$$
\max_{x\in\Omega}|x|=(\sum_{k=1}^nx_k^2)^{\frac12}>1,
$$
the ground states, as proved in Theorem~\ref{thmz2} , tend to $0$
as $r\to +\infty$.

Conjecture I. On the unit ball $B_n$, the top of the radial positive
solution becomes flatter as $r$ increases. As a bifurcation of the
1-peak radial solution in $r$, a 1-peak non-radial positive ground
state solution exists, i.e., SBP occurs, when $r$ increases and exceeds
a certain value. Its peak point goes to the boundary.

Conjecture II. On the hypercube $\Omega_n=(-1,1)^n$, as a
bifurcation of the BN symmetric positive solution in $r$, a 1-peak
BN asymmetric positive ground state solution exists, i.e., SBP
occurs, when $r$ increases and exceeds a certain value. The peak point
of the ground state is $(a_1,\dots ,a_n)$, where $a_i=a$ or $-a$,
$i=1,\dots ,n$ and $0<a<1$ is some number. If $\Omega_n$ is symmetric
about a hyperplane passing through the origin and the peak point,
the ground state keeps this symmetry and if $\Omega_n$ is symmetric
about a hyperplane only passing through the origin, the ground state
loses this symmetry. The peak point of the ground state goes to a
vertex of $\Omega_n$.

Conjecture III. On any open bounded domain $\Omega\subset\mathbb
R^n$ with $max_{x\in\Omega}|x|=(\sum_{k=1}^nx_k^2)^{\frac12}>1$, the
peak height of the ground states goes to $0$ as $r\to+\infty$.

Conjecture IV. On the hypercube $\Omega_n=(-1,1)^n$, when $r$ increases
and exceeds a certain value, the peak of the 1-peak BN
symmetric positive solution breaks into 2n peaks and when $r$ increases,
1-peak positive solutions with their peak points
$(x_1,\dots ,x_n)$ satisfying one of the followings,
$(\textbf{1})\; x_1=\dots=x_n>0$, $(\textbf{2})\; x_1=\dots=x_{n-1}>0, x_n=0$,\dots ,
$(\textbf{n})\; x_1>0, x_2=\dots=x_{n}=0$, will show up.

We hope that our numerical evidences can stimulate further analytic
verifications of those new phenomena.

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\end{document}
