Elliptic PDEs on unbounded sets












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I recently tried to apply the classical methods of Sobolev Spaces and the Lax-Milgram-theorem to a PDE on an unbounded domain. This did not work, since the Rellich-Kondrachov-Theorem can not be used and there is no Poincaré-inequality.
Then I read online that it is possible to define weighted Sobolev Spaces - for example $H^{1}_{0}(Omega)$ equipped with the norm
$|u|:=(int_{Omega}frac{u^{2}}{(1+|x|)^{2}}+(nabla{u})^{2})^{frac{1}{2}}$

in order to establish the desired inequality of the form:
$int_{Omega}frac{u^{2}}{(1+|x|)^{2}}le C int_{Omega}(nabla u)^{2}$



I suspect one could use the Hardy-inequality in order to prove it, but I couldn´t find any references.
Does anyone have any literature suggestions on weighted spaces for PDEs on unbounded sets?
And is it possible to prove that any solution in such a space decays pointwise at infinity?










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    $begingroup$


    I recently tried to apply the classical methods of Sobolev Spaces and the Lax-Milgram-theorem to a PDE on an unbounded domain. This did not work, since the Rellich-Kondrachov-Theorem can not be used and there is no Poincaré-inequality.
    Then I read online that it is possible to define weighted Sobolev Spaces - for example $H^{1}_{0}(Omega)$ equipped with the norm
    $|u|:=(int_{Omega}frac{u^{2}}{(1+|x|)^{2}}+(nabla{u})^{2})^{frac{1}{2}}$

    in order to establish the desired inequality of the form:
    $int_{Omega}frac{u^{2}}{(1+|x|)^{2}}le C int_{Omega}(nabla u)^{2}$



    I suspect one could use the Hardy-inequality in order to prove it, but I couldn´t find any references.
    Does anyone have any literature suggestions on weighted spaces for PDEs on unbounded sets?
    And is it possible to prove that any solution in such a space decays pointwise at infinity?










    share|cite|improve this question









    $endgroup$















      0












      0








      0


      0



      $begingroup$


      I recently tried to apply the classical methods of Sobolev Spaces and the Lax-Milgram-theorem to a PDE on an unbounded domain. This did not work, since the Rellich-Kondrachov-Theorem can not be used and there is no Poincaré-inequality.
      Then I read online that it is possible to define weighted Sobolev Spaces - for example $H^{1}_{0}(Omega)$ equipped with the norm
      $|u|:=(int_{Omega}frac{u^{2}}{(1+|x|)^{2}}+(nabla{u})^{2})^{frac{1}{2}}$

      in order to establish the desired inequality of the form:
      $int_{Omega}frac{u^{2}}{(1+|x|)^{2}}le C int_{Omega}(nabla u)^{2}$



      I suspect one could use the Hardy-inequality in order to prove it, but I couldn´t find any references.
      Does anyone have any literature suggestions on weighted spaces for PDEs on unbounded sets?
      And is it possible to prove that any solution in such a space decays pointwise at infinity?










      share|cite|improve this question









      $endgroup$




      I recently tried to apply the classical methods of Sobolev Spaces and the Lax-Milgram-theorem to a PDE on an unbounded domain. This did not work, since the Rellich-Kondrachov-Theorem can not be used and there is no Poincaré-inequality.
      Then I read online that it is possible to define weighted Sobolev Spaces - for example $H^{1}_{0}(Omega)$ equipped with the norm
      $|u|:=(int_{Omega}frac{u^{2}}{(1+|x|)^{2}}+(nabla{u})^{2})^{frac{1}{2}}$

      in order to establish the desired inequality of the form:
      $int_{Omega}frac{u^{2}}{(1+|x|)^{2}}le C int_{Omega}(nabla u)^{2}$



      I suspect one could use the Hardy-inequality in order to prove it, but I couldn´t find any references.
      Does anyone have any literature suggestions on weighted spaces for PDEs on unbounded sets?
      And is it possible to prove that any solution in such a space decays pointwise at infinity?







      sobolev-spaces






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      asked Dec 17 '18 at 20:35









      Falc14Falc14

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