All Questions
8 questions
5
votes
0
answers
132
views
Regularity of the spherical mean of a compactly-supported function
The problem
Consider a $C²$ function $f: X \to \mathbb{R}$, for some compact set $X \subset \mathbb{R}^d$ with $C^1$ boundary, say $\partial X$. I am only interested in $d\in \{2,3\}$.
Then, consider ...
- 555
2
votes
1
answer
157
views
Inequality with decreasing rearrangement and non-decreasing function
This question is a continuation of the question here.
Let $f^{*}$ be the usual decreasing rearrangement function of a measurable function $f$ on a measure space $(X, \mu)$. Let $1<p<n$ and set $$...
- 459
4
votes
1
answer
367
views
Inequality with decreasing rearrangement function
Let $f^{*}$ be the usual decreasing rearrangement function of a measurable function $f$ on a measure space $(X, \mu)$. Let $1<p<n$ and set $$p'=\frac{pn}{n-p}.$$ Also, let $g$ be a positive ...
- 459
0
votes
0
answers
66
views
Is there a dyadic cube decomposition where edge length is comparable to L^2 averages?
Suppose I have some measurable function $f : B_1(0) \to [0,1)$, which is pointwise very small, i.e. $\|f\|_{\infty} << 1$.
I'm looking to construct some kind of dyadic cube decomposition or ...
- 1,179
4
votes
1
answer
155
views
How do the balls maximizing the maximal function depend on their centers?
Let $\mu$ be a finite Borel measure on $\mathbb R^N$ and let $f\in L^1(\mu)$ be a non-negative function. Let $M_\mu f$ denote the maximal function of $f$ relative to $\mu$, i.e. $(M_\mu f)(x)=0$ if $\...
- 1,277
5
votes
0
answers
240
views
The boundary integral of a harmonic function
Let $\Omega\subset\mathbb{R}^{n}$ be a bounded
domain with smooth boundary and $f$ be a harmonic function on $\Omega.$
It is known that
$$
\limsup_{\varepsilon\rightarrow0^{+}}\intop_{\partial\Omega_{...
- 53
5
votes
2
answers
341
views
a modification on an infinite Bernoulli convolution
The distribution $\nu_{\lambda}$ of the random series $\sum\pm\lambda^n$ is the infinite convolution product of $\frac12(\delta_{-\lambda^n}+\delta_{\lambda^n})$. This problem has been studied ...
- 43.2k
43
votes
0
answers
819
views
A kaleidoscopic coloring of the plane
Problem. Is there a partition $\mathbb R^2=A\sqcup B$ of the Euclidean plane into two Lebesgue measurable sets such that for any disk $D$ of the unit radius we get $\lambda(A\cap D)=\lambda(B\cap D)=\...
- 41.8k