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Non-uniformly elliptic variational problems on BV

Lisa Beck, Franz Gmeineder, Mathias Schäffner

TL;DR

This work addresses regularity for relaxed minimizers of convex functionals with linear growth on BV, a regime that sits at the endpoint between standard superlinear $(p,q)$-growth and pure linear growth. By employing Lebesgue–Serrin–Marcellini relaxation and a carefully designed Ekeland-vanishing viscosity scheme, the authors derive universal $ ext{W}^{1,1}$-regularity and higher gradient integrability under a non-uniform ellipticity condition parameterized by $(oldsymbol{ extmu},q)$, with $q+oldsymbol{ extmu}<2+ rac{2}{n-1}$ and dimension-dependent lower bounds on $oldsymbol{ extmu}$. In two dimensions, a stronger set of assumptions yields local $C^{1,oldsymbol{eta}}$-regularity for relaxed minimizers. The results bridge the gap between the linear-growth endpoint and the superlinear regime, provide a sharp gradient-integrability framework, and include a dimension reduction for the singular set, all while avoiding integral representations of the relaxed functional and relying on BV-based analysis and measure-theoretic techniques. The methods have potential implications for endpoint growth problems such as $L ext{log}L$-type growth and other non-uniformly elliptic BV-variational problems.

Abstract

We establish $\mathrm{W}^{1,1}$-regularity and higher gradient integrability for relaxed minimizers of convex integral functionals on $\mathrm{BV}$. Unlike classical examples such as the minimal surface integrand, we only require linear growth from below but not necessarily from above. This typically comes with a non-uniformly degenerate elliptic behaviour, for which our results extend the presently available bounds from the superlinear growth case in a sharp way.

Non-uniformly elliptic variational problems on BV

TL;DR

This work addresses regularity for relaxed minimizers of convex functionals with linear growth on BV, a regime that sits at the endpoint between standard superlinear -growth and pure linear growth. By employing Lebesgue–Serrin–Marcellini relaxation and a carefully designed Ekeland-vanishing viscosity scheme, the authors derive universal -regularity and higher gradient integrability under a non-uniform ellipticity condition parameterized by , with and dimension-dependent lower bounds on . In two dimensions, a stronger set of assumptions yields local -regularity for relaxed minimizers. The results bridge the gap between the linear-growth endpoint and the superlinear regime, provide a sharp gradient-integrability framework, and include a dimension reduction for the singular set, all while avoiding integral representations of the relaxed functional and relying on BV-based analysis and measure-theoretic techniques. The methods have potential implications for endpoint growth problems such as -type growth and other non-uniformly elliptic BV-variational problems.

Abstract

We establish -regularity and higher gradient integrability for relaxed minimizers of convex integral functionals on . Unlike classical examples such as the minimal surface integrand, we only require linear growth from below but not necessarily from above. This typically comes with a non-uniformly degenerate elliptic behaviour, for which our results extend the presently available bounds from the superlinear growth case in a sharp way.
Paper Structure (28 sections, 31 theorems, 319 equations)

This paper contains 28 sections, 31 theorems, 319 equations.

Key Result

Theorem 1.1

Let $\Omega\subset\mathbb R^{n}$ be open and bounded with Lipschitz boundary. Moreover, let $F\in\operatorname{C}^{2}(\mathbb R^{N\times n})$ be a variational integrand with eq:1qgrowth and eq:muell1q, where $1\leq\mu,q<\infty$ satisfy Then, for any $u_{0}\in\operatorname{W}^{1,q}(\Omega;\mathbb R^{N})$, every relaxed minimizer $u\in\operatorname{BV}(\Omega;\mathbb R^{N})$ of $\mathscr{F}$ subjec

Theorems & Definitions (70)

  • Theorem 1.1: Universal higher gradient integrability
  • Theorem 1.2: Universal $\operatorname{C}^{1,\alpha}$-regularity in $n=2$ dimensions
  • Remark 1.3: Comparison with $(p,q)$- and $(\mu,s,q)$-growth conditions
  • Lemma 2.1
  • proof
  • Lemma 2.2
  • Lemma 2.3
  • Lemma 2.4
  • Definition 2.5: Recession function
  • Proposition 2.6: Reshetnyak's lower semicontinuity theorem
  • ...and 60 more