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John
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Embedding of weighted sobolev space with exponential weights

In the book by Bensoussan and Lions, they introduce the weighted spaces with exponentially decaying weights to study elliptic equations with bounded coefficients on the whole space $\mathbb{R}^n$. They mentioned that there are classical regularity results based on these spaces.

For example, for each $p\in [1,\infty)$, the weighted $L^p_\mu(\mathbb{R}^d)$ space on $\mathbb{R}^d$ is defined to be the set of Lebesgue measurable functions such that $f\omega_\mu(x)\in L^p(\mathbb{R}^n)$, i.e., $$\|f\|_{L^p_\mu}=\int_{\mathbb{R}^d}|f|^p\omega^p_\mu(x)\,dx< \infty,$$ where $\omega_\mu(x)=\exp(-\mu\sqrt{1+|x|^2})$ for some $\mu>0$, and the weighted sobolev space $W^{1,p}_\mu(\mathbb{R}^d)$ is defined to be the space of functions such that $u\omega_\mu\in L^p(\mathbb{R}^n)$ and $\partial_{x_i} u\omega_\mu\in L^p(\mathbb{R}^n)$, where $\partial_{x_i}$ denotes the weak derivative in the distribution sense. Similarly we define the high-order sobolev space $W^{2,p}_\mu(\mathbb{R}^d)$ such that $\partial_{x_ix_j}u\omega_\mu\in L^p$ for all $i,j$.

I am interested in a reference on the embedding properties between spaces of different orders. For example, it is pointed out in the book that the injection $$ W^{2,p}_\mu\hookrightarrow W^{1,p}_\nu \tag{1}$$ with $\nu>\mu$ is compact. Does it follow from the results for the classical sobolev space? Moreover, does the Gagliardo–Nirenberg–Sobolev inequality for the classical Sobolev space still hold? In particular, whether for $1\le p<n$, we have $$ \|u\|_{L^{p^*}_\mu(\mathbf{R}^n)}\leq C \|Du\|_{L^{p}_\mu(\mathbf{R}^n)}.$$

for some $p^*>p$? How about we allow $\nu$ to be larger than $\mu$ as in (1)?

John
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