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A Sobolev space is a vector space of functions equipped with a norm that is a combination of Lp-norms of the function itself and its derivatives up to a given order.
0
votes
1
answer
539
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Continuous Sobolev embedding
I have a question about Sobolev spaces.
In the following, we assume $d \ge 2$.
Let $D$ be a domain of $\mathbb{R}^d$. That is, $D$ is a connected open subset of $\mathbb{R}^d$. Note that $D$ is not n …
0
votes
1
answer
126
views
Boundary values of $f$, bounded linear operator
I have a question about Sobolev spaces
Let $U$ be a bounded Lipschitz domain of $\mathbb{R}^{d}$. $H^{1}(U)$ denotes the first order $L^2$-Sobolev space on $U$ with Neumann boundary condition.
It i …
0
votes
1
answer
156
views
Generators and Dirichlet forms
I have a question about a Dirichlet form.
Let $D$ be a open subset of $\mathbb{R}^d$. Then, we can define $H^{1}(D)$ by
\begin{equation*}
H^{1}(D)=\{f \in L^{2}(D,dx):\frac{\partial f}{\partial x_i} …
9
votes
2
answers
422
views
Core for a Sobolev space
Let $D$ be a domain of $\mathbb{R}^d$. That is, $D$ is a connected open subset of $\mathbb{R}^d$. The first-order Sobolev space $W^{1,2}(D)$ on $D$ is defined by
\begin{align*}
W^{1,2}(D)=\{f \in L^2( …
4
votes
1
answer
3k
views
Are compactly supported continuous functions dense in the Continuous functions of Sobolev sp... [closed]
I have a question about Sobolev space.
Let $\Omega$ be an open subset of $\mathbb{R}^{d}$,
we consider the Sobolev space
$H^{1}(\Omega):=\left\{ u \in L^{2}(\Omega) : D_{j}u \in L^{2}(\Omega), j=1 …
2
votes
2
answers
236
views
A Characterization of the traces of functions in $W^{1,2}$
I have a question about the traces of functions in $W^{1,2}$.
Let $D$ be a connected open subset of $\mathbb{R}^d$.We denote $W^{1,2}(D)$ by
\begin{align*}
W^{1,2}(D)=\{f \in L^{2}(D,dx) \mid \parti …
3
votes
1
answer
553
views
On the domain of the Neumann Laplacian
Let $U$ be a bounded domain of $\mathbb{R}^d$, and write $m$ for the Lebesgue measure on $U$. For $k=1,2$, we denote by $H^k(U)$ the set of all locally $m$-integrable functions $u\colon U \to \mathbb …
0
votes
1
answer
375
views
Functions satisfying Neumann boundary condition
I have a question about functions satisfying a condition.
Let $D \subset \mathbb{R}^d$ be a Lipschitz domain. That is, for each $x \in \partial D$, there exists an open neighborhood $U$ of $x$ in $\ …
0
votes
1
answer
756
views
About weak derivatives [closed]
I have a question about weak derivatives.
Let $u,v \in L^{1}_{loc}(U)$ (the space of locally integrable functions) for some
open set $\emptyset \neq U \in \mathbb{R}^{n}$. We often say that $v$ is th …
6
votes
1
answer
540
views
Volume doubling, uniform Poincaré, counterexample
The Poincaré inequality and the volume doubling property are important notions related to heat kernel estimates.
Pavel Gyrya and Laurent Saloff-Coste obtain the two sided heat kernel estimate of Neum …