Questions tagged [fractional-sobolev-spaces]
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9
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Why does the integrand $\frac{f(x)-f(y)}{|x-y|^\alpha}$ often appear when studying regularity?
Certain spaces (such as Besov, Holder, or Sobolev spaces) often measure regularity by function increments or difference quotients, and their norms contain integrands similar to
$$\frac{f(x)-f(y)}{|x-y|...
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Existence of $H^{1/2}(\partial\Omega)$-regular unit tangent field on smooth surface
Suppose that $\Omega$ is a bounded, smooth, simply connected domain in $\mathbb{R}^3$. My goal is to show that there is a $p(x) \in H^1(\Omega,\mathbb{S}^2)$ such that $p(x)$ lies on the tangent plane ...
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Strong convergence of a sequence in $L^2((0,T); H^{s,2}(\Omega)) \cap C([0,T];H^{-s,2}(\Omega))$, $0<s<1$
Let $u_n$ be a sequence with $u_n \in L^2((0,T);H^{1,2}(\Omega))$ and $\frac{\partial u_n}{\partial t} \in L^2((0,T);H^{1,2}(\Omega)^*)$. Then, how could one get a subsequence of $u_n$ that strongly ...
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$H^{s,\infty}$ via Triebel Lizorkin spaces
I know that
$F^s_{p,2} = H^{s,p}$
for $p \in (1, \infty)$, but what about $H^{s,1}$ and $H^{s,\infty}$? I know one extension for $F^0_{\infty,2}$ which should be BMO. But how do I get the $H^{s,\infty}...
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Proof of the equivalence between Triebel Spaces and Bessel Potential
I've encountered a question regarding the relationship between Triebel-Lizorkin spaces and Bessel potential spaces. Specifically, I understand that
$F^s_{p,2} = H^{s,p}$, for $p \in (1,\infty)$.
...
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For any $p, q \in [1,\infty]$ and $s \in (0,\infty)$, can we find some $f \in L^q - W^{s,p}$?
Sobolev inequalities show us when we can embed a Sobolev space into another.
However, I wonder if these inclusions are always proper.
More specifically, let $\Omega \subset \mathbb{R}^n$ be a bounded ...
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Dual of homogeneous Triebel-Lizorkin
Let $ p, q \in (1,\infty)$ and consider the homogeneous Triebel- Lizorkin space $\dot{F}^{s}_{p,q}$ to be the space of all tempered distributions (modulo polynomials) with
$$
[f]^{p}_{\dot{F}^{s}_{p,q}...
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Existence of an extension operator $E: W_0^{s,p}(\Omega)\rightarrow W^{s,p}(\mathbb{R}^d)$?
If $\Omega$ is an open Lipschitz domain with bounded boundary then their exists a continuous operator $E: W^{s,p}(\Omega) \rightarrow W^{s,p}(\mathbb{R}^d)$ where $s\in (0,1)$ such that $Eu=u$ on $\...
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Does the union of fractional Sobolev spaces fills $L^p$?
Let $\Omega\subset \Bbb R^d$ be any open set. Recall that for $s\in (0,1)$, the fractional Sobolev space $W^{s,p}(\Omega)$ is the collection of function in $L^p(\Omega$ such that
\begin{align*}
\iint_{...
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