Widely degenerate anisotropic diffusion: local boundedness and semicontinuity

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Main Authors: Ambrosio, Pasquale, Ciani, Simone, Cupini, Giovanni
Format: Preprint
Published: 2026
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author Ambrosio, Pasquale
Ciani, Simone
Cupini, Giovanni
author_facet Ambrosio, Pasquale
Ciani, Simone
Cupini, Giovanni
contents We investigate the regularity of local weak solutions to evolution equations of the form \[ \partial_{t}u\,=\,\sum_{i=1}^{n}\,\partial_{x_{i}}\left[a_{i}(x,t)\,(\vert\partial_{x_{i}}u\vert-δ_{i})_{+}^{p_{i}-1}\,\frac{\partial_{x_{i}}u}{\vert\partial_{x_{i}}u\vert}\right]\,\,\,\,\,\,\,\,\,\,\mathrm{in}\,\,\,Ω_{T}\,=\,Ω\times(0,T)\,, \] where $Ω$ is a bounded domain in $\mathbb{R}^{n}$ with $n\geq2$, the coefficients $a_{i}$ are measurable and bounded, $p_{i}>1$ and $δ_{i}\geq0$ are fixed parameters. Under suitable assumptions on the exponents $p_{i}$, we first show that the local boundedness of weak solutions follows from their membership in an appropriate non-homogeneous parabolic De Giorgi class. We then establish the existence of semicontinuous representatives for local weak sub(super)-solutions. Our analysis extends analogous results available for less degenerate operators and generalizes the local boundedness results obtained in [7] to fully anisotropic, widely degenerate parabolic PDEs with non-smooth coefficients depending additionally on the space-time variables $(x,t)$, whose growth is governed by a family of exponents $p_{i}$ rather than by a single exponent.
format Preprint
id arxiv_https___arxiv_org_abs_2604_20597
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Widely degenerate anisotropic diffusion: local boundedness and semicontinuity
Ambrosio, Pasquale
Ciani, Simone
Cupini, Giovanni
Analysis of PDEs
35B45, 35B65, 35K10, 35K65, 35K92
We investigate the regularity of local weak solutions to evolution equations of the form \[ \partial_{t}u\,=\,\sum_{i=1}^{n}\,\partial_{x_{i}}\left[a_{i}(x,t)\,(\vert\partial_{x_{i}}u\vert-δ_{i})_{+}^{p_{i}-1}\,\frac{\partial_{x_{i}}u}{\vert\partial_{x_{i}}u\vert}\right]\,\,\,\,\,\,\,\,\,\,\mathrm{in}\,\,\,Ω_{T}\,=\,Ω\times(0,T)\,, \] where $Ω$ is a bounded domain in $\mathbb{R}^{n}$ with $n\geq2$, the coefficients $a_{i}$ are measurable and bounded, $p_{i}>1$ and $δ_{i}\geq0$ are fixed parameters. Under suitable assumptions on the exponents $p_{i}$, we first show that the local boundedness of weak solutions follows from their membership in an appropriate non-homogeneous parabolic De Giorgi class. We then establish the existence of semicontinuous representatives for local weak sub(super)-solutions. Our analysis extends analogous results available for less degenerate operators and generalizes the local boundedness results obtained in [7] to fully anisotropic, widely degenerate parabolic PDEs with non-smooth coefficients depending additionally on the space-time variables $(x,t)$, whose growth is governed by a family of exponents $p_{i}$ rather than by a single exponent.
title Widely degenerate anisotropic diffusion: local boundedness and semicontinuity
topic Analysis of PDEs
35B45, 35B65, 35K10, 35K65, 35K92
url https://arxiv.org/abs/2604.20597