Showing that a multivariable function is Borel measurable. [closed]

Multi tool use
Multi tool use












1












$begingroup$


I want to show that the following function is Borel measurable. Consider:
$$f: mathbb{R}^2 rightarrow mathbb{R}:left{
begin{array}{ll}
sinleft(frac{1}{x-y}right) & x> y \
x^2 + y^2 & xleq y. \
end{array}
right. $$



So I think one can prove it by looking if the function is continuous (so measurable) or proving it by the defintition of a Borel measurable function. By proving it from the defenition, one can use that ${x:f(x)>a}$ is a Borel set. But I don't know how to proceed with this defenition.










share|cite|improve this question









$endgroup$



closed as off-topic by Nosrati, Paul Frost, Cesareo, José Carlos Santos, amWhy Jan 6 at 20:54


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." – Nosrati, Paul Frost, Cesareo, José Carlos Santos, amWhy

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





















    1












    $begingroup$


    I want to show that the following function is Borel measurable. Consider:
    $$f: mathbb{R}^2 rightarrow mathbb{R}:left{
    begin{array}{ll}
    sinleft(frac{1}{x-y}right) & x> y \
    x^2 + y^2 & xleq y. \
    end{array}
    right. $$



    So I think one can prove it by looking if the function is continuous (so measurable) or proving it by the defintition of a Borel measurable function. By proving it from the defenition, one can use that ${x:f(x)>a}$ is a Borel set. But I don't know how to proceed with this defenition.










    share|cite|improve this question









    $endgroup$



    closed as off-topic by Nosrati, Paul Frost, Cesareo, José Carlos Santos, amWhy Jan 6 at 20:54


    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." – Nosrati, Paul Frost, Cesareo, José Carlos Santos, amWhy

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



















      1












      1








      1





      $begingroup$


      I want to show that the following function is Borel measurable. Consider:
      $$f: mathbb{R}^2 rightarrow mathbb{R}:left{
      begin{array}{ll}
      sinleft(frac{1}{x-y}right) & x> y \
      x^2 + y^2 & xleq y. \
      end{array}
      right. $$



      So I think one can prove it by looking if the function is continuous (so measurable) or proving it by the defintition of a Borel measurable function. By proving it from the defenition, one can use that ${x:f(x)>a}$ is a Borel set. But I don't know how to proceed with this defenition.










      share|cite|improve this question









      $endgroup$




      I want to show that the following function is Borel measurable. Consider:
      $$f: mathbb{R}^2 rightarrow mathbb{R}:left{
      begin{array}{ll}
      sinleft(frac{1}{x-y}right) & x> y \
      x^2 + y^2 & xleq y. \
      end{array}
      right. $$



      So I think one can prove it by looking if the function is continuous (so measurable) or proving it by the defintition of a Borel measurable function. By proving it from the defenition, one can use that ${x:f(x)>a}$ is a Borel set. But I don't know how to proceed with this defenition.







      functional-analysis measure-theory borel-sets






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Jan 5 at 19:05









      Belgium_PhysicsBelgium_Physics

      325110




      325110




      closed as off-topic by Nosrati, Paul Frost, Cesareo, José Carlos Santos, amWhy Jan 6 at 20:54


      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." – Nosrati, Paul Frost, Cesareo, José Carlos Santos, amWhy

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







      closed as off-topic by Nosrati, Paul Frost, Cesareo, José Carlos Santos, amWhy Jan 6 at 20:54


      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." – Nosrati, Paul Frost, Cesareo, José Carlos Santos, amWhy

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






















          0






          active

          oldest

          votes

















          0






          active

          oldest

          votes








          0






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes

          uH OL6fL fFGkgTPtstRDpKU q,eYgDiWneiScQT0aLj0HspOfeSQd OXfo9sfjysS6YZDDgk BqgtfFEoQ u7KjQiA4M9
          7Rn eCtrmSjf ut,vnQuuB738UA6X3AeHnjzCCTVmwj2LTIV,W0bXqZP

          Popular posts from this blog

          Human spaceflight

          Can not write log (Is /dev/pts mounted?) - openpty in Ubuntu-on-Windows?

          Antiochus X Eusebes