A closed set in the plane that is pluripolar in $mathbb{C}^{2}$












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Let $ E $ be a compact set in $mathbb{R}^{2}$. We know that if $E$ is polar, then it is a set of isolated points. Now, suppose $E$ is pluripolar when regarded as $Esubsetmathbb{R}^{2}subset mathbb{C}^{2}$, i.e., there is a plurisubharmonic function on an open neighborhood of $E$ in $mathbb{C}^{2}$ that is not identically $-infty$, but on $E$ it is equal to $-infty$. Can we still say that $E$ is a set of isolated points?










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    1












    $begingroup$


    Let $ E $ be a compact set in $mathbb{R}^{2}$. We know that if $E$ is polar, then it is a set of isolated points. Now, suppose $E$ is pluripolar when regarded as $Esubsetmathbb{R}^{2}subset mathbb{C}^{2}$, i.e., there is a plurisubharmonic function on an open neighborhood of $E$ in $mathbb{C}^{2}$ that is not identically $-infty$, but on $E$ it is equal to $-infty$. Can we still say that $E$ is a set of isolated points?










    share|cite|improve this question











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      1












      1








      1





      $begingroup$


      Let $ E $ be a compact set in $mathbb{R}^{2}$. We know that if $E$ is polar, then it is a set of isolated points. Now, suppose $E$ is pluripolar when regarded as $Esubsetmathbb{R}^{2}subset mathbb{C}^{2}$, i.e., there is a plurisubharmonic function on an open neighborhood of $E$ in $mathbb{C}^{2}$ that is not identically $-infty$, but on $E$ it is equal to $-infty$. Can we still say that $E$ is a set of isolated points?










      share|cite|improve this question











      $endgroup$




      Let $ E $ be a compact set in $mathbb{R}^{2}$. We know that if $E$ is polar, then it is a set of isolated points. Now, suppose $E$ is pluripolar when regarded as $Esubsetmathbb{R}^{2}subset mathbb{C}^{2}$, i.e., there is a plurisubharmonic function on an open neighborhood of $E$ in $mathbb{C}^{2}$ that is not identically $-infty$, but on $E$ it is equal to $-infty$. Can we still say that $E$ is a set of isolated points?







      complex-analysis






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      edited Jan 22 at 20:31









      Alon Amit

      10.6k3768




      10.6k3768










      asked Jan 20 at 1:14









      M. RahmatM. Rahmat

      291212




      291212






















          1 Answer
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          $begingroup$

          Zero sets of non-constant holomorphic functions $f$ are pluripolar (because $log |f|$ is plurisubharmonic), so the example $f(z,w) = w$ shows that the (complex one-dimensional) $z$-plane is a pluripolar set in $mathbb{C}^2$ (viewed as the complex two-dimensional $(z,w)$-space.)






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          • $begingroup$
            Sorry! I didn't get it. But the $z-$plane does not turn $log|f|$ into $-infty$...
            $endgroup$
            – M. Rahmat
            Jan 24 at 2:35






          • 1




            $begingroup$
            @M.Rahmat: $log |f|$ is $-infty$ exactly at the zeros of $f$, which in this case is given by the equation $w=0$, i.e., the $z$-plane.
            $endgroup$
            – Lukas Geyer
            Jan 24 at 4:03










          • $begingroup$
            Now i got it! Thanks
            $endgroup$
            – M. Rahmat
            Jan 24 at 19:45











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          1 Answer
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          1 Answer
          1






          active

          oldest

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          active

          oldest

          votes






          active

          oldest

          votes









          1





          +50







          $begingroup$

          Zero sets of non-constant holomorphic functions $f$ are pluripolar (because $log |f|$ is plurisubharmonic), so the example $f(z,w) = w$ shows that the (complex one-dimensional) $z$-plane is a pluripolar set in $mathbb{C}^2$ (viewed as the complex two-dimensional $(z,w)$-space.)






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Sorry! I didn't get it. But the $z-$plane does not turn $log|f|$ into $-infty$...
            $endgroup$
            – M. Rahmat
            Jan 24 at 2:35






          • 1




            $begingroup$
            @M.Rahmat: $log |f|$ is $-infty$ exactly at the zeros of $f$, which in this case is given by the equation $w=0$, i.e., the $z$-plane.
            $endgroup$
            – Lukas Geyer
            Jan 24 at 4:03










          • $begingroup$
            Now i got it! Thanks
            $endgroup$
            – M. Rahmat
            Jan 24 at 19:45
















          1





          +50







          $begingroup$

          Zero sets of non-constant holomorphic functions $f$ are pluripolar (because $log |f|$ is plurisubharmonic), so the example $f(z,w) = w$ shows that the (complex one-dimensional) $z$-plane is a pluripolar set in $mathbb{C}^2$ (viewed as the complex two-dimensional $(z,w)$-space.)






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Sorry! I didn't get it. But the $z-$plane does not turn $log|f|$ into $-infty$...
            $endgroup$
            – M. Rahmat
            Jan 24 at 2:35






          • 1




            $begingroup$
            @M.Rahmat: $log |f|$ is $-infty$ exactly at the zeros of $f$, which in this case is given by the equation $w=0$, i.e., the $z$-plane.
            $endgroup$
            – Lukas Geyer
            Jan 24 at 4:03










          • $begingroup$
            Now i got it! Thanks
            $endgroup$
            – M. Rahmat
            Jan 24 at 19:45














          1





          +50







          1





          +50



          1




          +50



          $begingroup$

          Zero sets of non-constant holomorphic functions $f$ are pluripolar (because $log |f|$ is plurisubharmonic), so the example $f(z,w) = w$ shows that the (complex one-dimensional) $z$-plane is a pluripolar set in $mathbb{C}^2$ (viewed as the complex two-dimensional $(z,w)$-space.)






          share|cite|improve this answer









          $endgroup$



          Zero sets of non-constant holomorphic functions $f$ are pluripolar (because $log |f|$ is plurisubharmonic), so the example $f(z,w) = w$ shows that the (complex one-dimensional) $z$-plane is a pluripolar set in $mathbb{C}^2$ (viewed as the complex two-dimensional $(z,w)$-space.)







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jan 22 at 21:53









          Lukas GeyerLukas Geyer

          13.8k1555




          13.8k1555












          • $begingroup$
            Sorry! I didn't get it. But the $z-$plane does not turn $log|f|$ into $-infty$...
            $endgroup$
            – M. Rahmat
            Jan 24 at 2:35






          • 1




            $begingroup$
            @M.Rahmat: $log |f|$ is $-infty$ exactly at the zeros of $f$, which in this case is given by the equation $w=0$, i.e., the $z$-plane.
            $endgroup$
            – Lukas Geyer
            Jan 24 at 4:03










          • $begingroup$
            Now i got it! Thanks
            $endgroup$
            – M. Rahmat
            Jan 24 at 19:45


















          • $begingroup$
            Sorry! I didn't get it. But the $z-$plane does not turn $log|f|$ into $-infty$...
            $endgroup$
            – M. Rahmat
            Jan 24 at 2:35






          • 1




            $begingroup$
            @M.Rahmat: $log |f|$ is $-infty$ exactly at the zeros of $f$, which in this case is given by the equation $w=0$, i.e., the $z$-plane.
            $endgroup$
            – Lukas Geyer
            Jan 24 at 4:03










          • $begingroup$
            Now i got it! Thanks
            $endgroup$
            – M. Rahmat
            Jan 24 at 19:45
















          $begingroup$
          Sorry! I didn't get it. But the $z-$plane does not turn $log|f|$ into $-infty$...
          $endgroup$
          – M. Rahmat
          Jan 24 at 2:35




          $begingroup$
          Sorry! I didn't get it. But the $z-$plane does not turn $log|f|$ into $-infty$...
          $endgroup$
          – M. Rahmat
          Jan 24 at 2:35




          1




          1




          $begingroup$
          @M.Rahmat: $log |f|$ is $-infty$ exactly at the zeros of $f$, which in this case is given by the equation $w=0$, i.e., the $z$-plane.
          $endgroup$
          – Lukas Geyer
          Jan 24 at 4:03




          $begingroup$
          @M.Rahmat: $log |f|$ is $-infty$ exactly at the zeros of $f$, which in this case is given by the equation $w=0$, i.e., the $z$-plane.
          $endgroup$
          – Lukas Geyer
          Jan 24 at 4:03












          $begingroup$
          Now i got it! Thanks
          $endgroup$
          – M. Rahmat
          Jan 24 at 19:45




          $begingroup$
          Now i got it! Thanks
          $endgroup$
          – M. Rahmat
          Jan 24 at 19:45


















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