On a p-Laplace equation with multiple critical nonlinearities

Using the Mountain-Pass Theorem of Ambrosetti and Rabinowitz we prove that $?{\mathrm{\Delta }}_{p}u?\mu {|x|}^{?p}{u}^{p?1}={|x|}^{?s}{u}^{p^{?}(s)?1}+u^{p^{?}?1}$ admits a positive weak solution in ${\mathbb{R}}^n$ of class $D_1^p({\mathbb{R}}^n)\cap C^1({\mathbb{R}}^n?\{0\})$, whenever $\mu <{\mu }_1$, and ${\mu }_1={[(n?p)/p]}^p$. The technique is based on the existence of extremals of some Hardy–Sobolev type embeddings of independent interest. We also show that if $u\in D_1^p({\mathbb{R}}^n)$ is a weak solution in ${\mathbb{R}}^n$ of $?{\mathrm{\Delta }}_{p}u?\mu {|x|}^{?p}{|u|}^{p?2}u={|x|}^{?s}{|u|}^{p^{?}(s)?2}u+{|u|}^{q?2}u$, then $u\equiv 0$ when either $1<q<p^{?}$, or $q>p^{?}$ and u is also of class $L_{\mathrm{loc}}^{\infty }({\mathbb{R}}^n?\{0\})$.     

On the sub poly-harmonic property for solutions to (−Δ)pu < 0 in Rn

In this note, we mainly study the relation between the sign of ${(?\mathrm{\Delta })}^{p}u$ and ${(?\mathrm{\Delta })}^{p?i}u$ in ${\mathbb{R}}^n$ with $p?2$ and $n?2$ for $1?i?p?1$. Given the differential inequality ${(?\mathrm{\Delta })}^{p}u<0$, first we provide several sufficient conditions so that ${(?\mathrm{\Delta })}^{p?1}u<0$ holds. Then we provide conditions such that ${(?\mathrm{\Delta })}^{i}u<0$ for all $i=1,2,\dots ,p?1$, which is known as the sub poly-harmonic property for u. In the last part of the note, we revisit the super poly-harmonic property for solutions to ${(?\mathrm{\Delta })}^{p}u={\mathrm{e}}^{2pu}$ and ${(?\mathrm{\Delta })}^{p}u=u^q$ with $q>0$ in ${\mathbb{R}}^n$.     

A note on the number of nodal solutions of an elliptic equation with symmetry

We consider the semilinear problem $-\Delta u+\lambda u={\left|u\right|}^{p-2}u$ in $\Omega$, $u=0$ on $\partial \Omega$, where $\Omega \subset {\mathbb{R}}^N$ is a bounded smooth domain and $2<p<2^1=2N/(N-2)$. We show that if $\Omega$ is invariant under a nontrivial orthogonal involution then, for $\lambda >0$ sufficiently large, the equivariant topology of $\Omega$ is related to the number of solutions which change sign exactly once.     

Solutions for semilinear elliptic problems with critical Sobolev–Hardy exponents in RN

Let $N\ge 3,0\le s<2,0\le \mu <{\left(\frac{N-2}{2}\right)}^2$ and $2^1\left(s\right)≔\frac{2(N-s)}{N-2}$ be the critical Sobolev–Hardy exponents. Via variational methods and the analytic technique, we prove the existence of a nontrivial solution to the singular semilinear problem $-\Delta u-\mu \frac{u}{{\left|x\right|}^2}+u=\frac{{\left|u\right|}^{2^1\left(s\right)-2}}{{\left|x\right|}^s}u+f\left(u\right),u\in H_r^1\left({\mathbb{R}}^N\right)$, for $N\ge 4,0\le \mu \le \bar{\mu }-1$ and suitable functions $f\left(u\right)$.