## Illinois Journal of Mathematics

### Traces of monotone functions in weighted Sobolev spaces

#### Abstract

Consider monotone functions $u\colon \mathbb{B}^n\to \mathbb{R}$ in the weighted Sobolev space $W^{1,p}(\mathbb{B}^n;w)$, where $n-1<p\leq n$ and $w$ is a weight in the class $A_q$ for some $1\leq q<{{p}/({n-1})}$ which has a certain symmetry property with respect to $\partial \mathbb{B}^n$. We prove that $u$ has nontangential limits at all points of $\partial \mathbb{B}^n$ except possibly those on a set $E$ of weighted $(p,w)$-capacity zero. The proof is based on a new weighted oscillation estimate (Theorem 1) that may be of independent interest. In the special case $w(x)=|1-|x||^\alpha$, the weighted $(p,w)$-capacity of a ball can be easily estimated to conclude that the Hausdorff dimension of the set $E$ is smaller than or equal to $\alpha+n-p$, where $0\leq \alpha<{(p-(n-1))}/{(n-1)}$.

#### Article information

Source
Illinois J. Math., Volume 45, Number 2 (2001), 403-422.

Dates
First available in Project Euclid: 13 November 2009

https://projecteuclid.org/euclid.ijm/1258138347

Digital Object Identifier
doi:10.1215/ijm/1258138347

Mathematical Reviews number (MathSciNet)
MR1878611

Zentralblatt MATH identifier
0988.30015

#### Citation

Manfredi, Juan J.; Villamor, Enrique. Traces of monotone functions in weighted Sobolev spaces. Illinois J. Math. 45 (2001), no. 2, 403--422. doi:10.1215/ijm/1258138347. https://projecteuclid.org/euclid.ijm/1258138347