Inner of metric completion












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I am reading a proof where we have the following:





  • $M$ a metric space


  • $N$ its metric completion


It is then stated: for $yin N$ let ($y_s$) be a Cauchy sequence converging to y with $y_sin M$.



I do not understand why can we choose $y_sin M$.



Do we have $yin Nsetminus M Rightarrow yinpartial M$ ?



Edit



It is my understanding a property of the completion is being the smallest complete space $N$ such that $Msubset N$, and so the intuition tells me the above should hold. But I did not manage proving it yet.










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$endgroup$

















    0












    $begingroup$


    I am reading a proof where we have the following:





    • $M$ a metric space


    • $N$ its metric completion


    It is then stated: for $yin N$ let ($y_s$) be a Cauchy sequence converging to y with $y_sin M$.



    I do not understand why can we choose $y_sin M$.



    Do we have $yin Nsetminus M Rightarrow yinpartial M$ ?



    Edit



    It is my understanding a property of the completion is being the smallest complete space $N$ such that $Msubset N$, and so the intuition tells me the above should hold. But I did not manage proving it yet.










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      I am reading a proof where we have the following:





      • $M$ a metric space


      • $N$ its metric completion


      It is then stated: for $yin N$ let ($y_s$) be a Cauchy sequence converging to y with $y_sin M$.



      I do not understand why can we choose $y_sin M$.



      Do we have $yin Nsetminus M Rightarrow yinpartial M$ ?



      Edit



      It is my understanding a property of the completion is being the smallest complete space $N$ such that $Msubset N$, and so the intuition tells me the above should hold. But I did not manage proving it yet.










      share|cite|improve this question











      $endgroup$




      I am reading a proof where we have the following:





      • $M$ a metric space


      • $N$ its metric completion


      It is then stated: for $yin N$ let ($y_s$) be a Cauchy sequence converging to y with $y_sin M$.



      I do not understand why can we choose $y_sin M$.



      Do we have $yin Nsetminus M Rightarrow yinpartial M$ ?



      Edit



      It is my understanding a property of the completion is being the smallest complete space $N$ such that $Msubset N$, and so the intuition tells me the above should hold. But I did not manage proving it yet.







      analysis






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      edited Jan 25 at 10:04







      nate

















      asked Jan 25 at 10:00









      natenate

      1186




      1186






















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          $begingroup$

          Yes, $M$ is dense in $N$ by the very definition of completion. Ref. https://en.wikipedia.org/wiki/Complete_metric_space






          share|cite|improve this answer









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            $begingroup$

            Yes, $M$ is dense in $N$ by the very definition of completion. Ref. https://en.wikipedia.org/wiki/Complete_metric_space






            share|cite|improve this answer









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              1












              $begingroup$

              Yes, $M$ is dense in $N$ by the very definition of completion. Ref. https://en.wikipedia.org/wiki/Complete_metric_space






              share|cite|improve this answer









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                $begingroup$

                Yes, $M$ is dense in $N$ by the very definition of completion. Ref. https://en.wikipedia.org/wiki/Complete_metric_space






                share|cite|improve this answer









                $endgroup$



                Yes, $M$ is dense in $N$ by the very definition of completion. Ref. https://en.wikipedia.org/wiki/Complete_metric_space







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Jan 25 at 10:01









                Kavi Rama MurthyKavi Rama Murthy

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