When is $ overline {T(B)}$ compact? [closed]












1












$begingroup$


Let $V$ and $W$ be normed linear spaces and let $ T : V to W$ be a continuous linear operator. Let $B$ be the closed unit ball in $V$ . In which of the
following cases is $ overline {T(B)}$ compact?





  • $ V = C^1[0, 1],W = C[0, 1]$ and $T(f) = f$.


  • $V = W = l_2$ and $T(x) = (0,x_1,x_2,ldots)$, where $x = (x_n)in l_2$.


  • $V = W = l_2$ and $T(x) = (x_1, x_2,x_{10}, 0, 0,0,ldots)$, where $x = (x_n)in l_2$.


This is a question from a PhD entrance exam,I cant show any work.



I am sorry for that,Can you kindly give some hints










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closed as off-topic by Math_QED, Nosrati, RRL, amWhy, Kavi Rama Murthy Dec 28 '18 at 7:33


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Math_QED, Nosrati, RRL, amWhy, Kavi Rama Murthy

If this question can be reworded to fit the rules in the help center, please edit the question.





















    1












    $begingroup$


    Let $V$ and $W$ be normed linear spaces and let $ T : V to W$ be a continuous linear operator. Let $B$ be the closed unit ball in $V$ . In which of the
    following cases is $ overline {T(B)}$ compact?





    • $ V = C^1[0, 1],W = C[0, 1]$ and $T(f) = f$.


    • $V = W = l_2$ and $T(x) = (0,x_1,x_2,ldots)$, where $x = (x_n)in l_2$.


    • $V = W = l_2$ and $T(x) = (x_1, x_2,x_{10}, 0, 0,0,ldots)$, where $x = (x_n)in l_2$.


    This is a question from a PhD entrance exam,I cant show any work.



    I am sorry for that,Can you kindly give some hints










    share|cite|improve this question









    $endgroup$



    closed as off-topic by Math_QED, Nosrati, RRL, amWhy, Kavi Rama Murthy Dec 28 '18 at 7:33


    This question appears to be off-topic. The users who voted to close gave this specific reason:


    • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Math_QED, Nosrati, RRL, amWhy, Kavi Rama Murthy

    If this question can be reworded to fit the rules in the help center, please edit the question.



















      1












      1








      1





      $begingroup$


      Let $V$ and $W$ be normed linear spaces and let $ T : V to W$ be a continuous linear operator. Let $B$ be the closed unit ball in $V$ . In which of the
      following cases is $ overline {T(B)}$ compact?





      • $ V = C^1[0, 1],W = C[0, 1]$ and $T(f) = f$.


      • $V = W = l_2$ and $T(x) = (0,x_1,x_2,ldots)$, where $x = (x_n)in l_2$.


      • $V = W = l_2$ and $T(x) = (x_1, x_2,x_{10}, 0, 0,0,ldots)$, where $x = (x_n)in l_2$.


      This is a question from a PhD entrance exam,I cant show any work.



      I am sorry for that,Can you kindly give some hints










      share|cite|improve this question









      $endgroup$




      Let $V$ and $W$ be normed linear spaces and let $ T : V to W$ be a continuous linear operator. Let $B$ be the closed unit ball in $V$ . In which of the
      following cases is $ overline {T(B)}$ compact?





      • $ V = C^1[0, 1],W = C[0, 1]$ and $T(f) = f$.


      • $V = W = l_2$ and $T(x) = (0,x_1,x_2,ldots)$, where $x = (x_n)in l_2$.


      • $V = W = l_2$ and $T(x) = (x_1, x_2,x_{10}, 0, 0,0,ldots)$, where $x = (x_n)in l_2$.


      This is a question from a PhD entrance exam,I cant show any work.



      I am sorry for that,Can you kindly give some hints







      functional-analysis compactness






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Dec 24 '18 at 9:37









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      closed as off-topic by Math_QED, Nosrati, RRL, amWhy, Kavi Rama Murthy Dec 28 '18 at 7:33


      This question appears to be off-topic. The users who voted to close gave this specific reason:


      • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Math_QED, Nosrati, RRL, amWhy, Kavi Rama Murthy

      If this question can be reworded to fit the rules in the help center, please edit the question.







      closed as off-topic by Math_QED, Nosrati, RRL, amWhy, Kavi Rama Murthy Dec 28 '18 at 7:33


      This question appears to be off-topic. The users who voted to close gave this specific reason:


      • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Math_QED, Nosrati, RRL, amWhy, Kavi Rama Murthy

      If this question can be reworded to fit the rules in the help center, please edit the question.






















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