<p>We prove the local boundedness of local weak solutions to the parabolic equation <Equation ID="Equ39"> <EquationSource Format="TEX">\( \partial _{t}u\,=\,\sum _{i=1}^{n}\partial _{x_{i}}\left[ (\vert u_{x_{i}}\vert -\delta _{i})_{+}^{p-1}\frac{u_{x_{i}}}{\vert u_{x_{i}}\vert }\right] \,\,\,\,\,\,\,\,\,\,\textrm{in}\,\,\,\Omega _{T}=\Omega \times (0,T]\,, \)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <msub> <mi>∂</mi> <mi>t</mi> </msub> <mi>u</mi> <mspace width="0.166667em" /> <mo>=</mo> <mspace width="0.166667em" /> <munderover> <mo>∑</mo> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </munderover> <msub> <mi>∂</mi> <msub> <mi>x</mi> <mi>i</mi> </msub> </msub> <mfenced close="]" open="["> <mrow> <mo stretchy="false">(</mo> <mo stretchy="false">|</mo> </mrow> <msub> <mi>u</mi> <msub> <mi>x</mi> <mi>i</mi> </msub> </msub> <msubsup> <mrow> <mo stretchy="false">|</mo> <mo>-</mo> <msub> <mi>δ</mi> <mi>i</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mrow> <mo>+</mo> </mrow> <mrow> <mi>p</mi> <mo>-</mo> <mn>1</mn> </mrow> </msubsup> <mfrac> <msub> <mi>u</mi> <msub> <mi>x</mi> <mi>i</mi> </msub> </msub> <mrow> <mrow> <mo stretchy="false">|</mo> </mrow> <msub> <mi>u</mi> <msub> <mi>x</mi> <mi>i</mi> </msub> </msub> <mrow> <mo stretchy="false">|</mo> </mrow> </mrow> </mfrac> </mfenced> <mspace width="0.166667em" /> <mspace width="0.166667em" /> <mspace width="0.166667em" /> <mspace width="0.166667em" /> <mspace width="0.166667em" /> <mspace width="0.166667em" /> <mspace width="0.166667em" /> <mspace width="0.166667em" /> <mspace width="0.166667em" /> <mspace width="0.166667em" /> <mtext>in</mtext> <mspace width="0.166667em" /> <mspace width="0.166667em" /> <mspace width="0.166667em" /> <msub> <mi mathvariant="normal">Ω</mi> <mi>T</mi> </msub> <mo>=</mo> <mi mathvariant="normal">Ω</mi> <mo>×</mo> <mrow> <mo stretchy="false">(</mo> <mn>0</mn> <mo>,</mo> <mi>T</mi> <mo stretchy="false">]</mo> </mrow> <mspace width="0.166667em" /> <mo>,</mo> </mrow> </math></EquationSource> </Equation>where <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\Omega \)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Ω</mi> </math></EquationSource> </InlineEquation> is a bounded domain in <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\mathbb {R}}^{n}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi mathvariant="double-struck">R</mi> </mrow> <mi>n</mi> </msup> </math></EquationSource> </InlineEquation> with <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(n\ge 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mo>≥</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(p\ge 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>p</mi> <mo>≥</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\delta _{1},\ldots ,\delta _{n}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>δ</mi> <mn>1</mn> </msub> <mo>,</mo> <mo>…</mo> <mo>,</mo> <msub> <mi>δ</mi> <mi>n</mi> </msub> </mrow> </math></EquationSource> </InlineEquation> are non-negative numbers and <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\left( \,\cdot \,\right) _{+}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mfenced close=")" open="("> <mspace width="0.166667em" /> <mo>·</mo> <mspace width="0.166667em" /> </mfenced> <mo>+</mo> </msub> </math></EquationSource> </InlineEquation> denotes the positive part. The main novelty here is that the above equation combines an orthotropic structure with a strongly degenerate behavior. The core result of this paper thus extends a classical boundedness theorem, originally proved for the parabolic <i>p</i>-Laplacian, to a widely degenerate anisotropic setting. As a byproduct, we also obtain the local boundedness of local weak solutions to the isotropic counterpart of the above equation.</p>

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Local boundedness for weak solutions to strongly degenerate orthotropic parabolic equations

  • Pasquale Ambrosio,
  • Simone Ciani

摘要

We prove the local boundedness of local weak solutions to the parabolic equation \( \partial _{t}u\,=\,\sum _{i=1}^{n}\partial _{x_{i}}\left[ (\vert u_{x_{i}}\vert -\delta _{i})_{+}^{p-1}\frac{u_{x_{i}}}{\vert u_{x_{i}}\vert }\right] \,\,\,\,\,\,\,\,\,\,\textrm{in}\,\,\,\Omega _{T}=\Omega \times (0,T]\,, \) t u = i = 1 n x i ( | u x i | - δ i ) + p - 1 u x i | u x i | in Ω T = Ω × ( 0 , T ] , where \(\Omega \) Ω is a bounded domain in \({\mathbb {R}}^{n}\) R n with \(n\ge 2\) n 2 , \(p\ge 2\) p 2 , \(\delta _{1},\ldots ,\delta _{n}\) δ 1 , , δ n are non-negative numbers and \(\left( \,\cdot \,\right) _{+}\) · + denotes the positive part. The main novelty here is that the above equation combines an orthotropic structure with a strongly degenerate behavior. The core result of this paper thus extends a classical boundedness theorem, originally proved for the parabolic p-Laplacian, to a widely degenerate anisotropic setting. As a byproduct, we also obtain the local boundedness of local weak solutions to the isotropic counterpart of the above equation.