Showing that a multivariable function is Borel measurable. [on hold]












1














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.










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put on hold as off-topic by Nosrati, Paul Frost, Cesareo, José Carlos Santos, amWhy yesterday


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














    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













    put on hold as off-topic by Nosrati, Paul Frost, Cesareo, José Carlos Santos, amWhy yesterday


    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







      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













      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






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      asked 2 days ago









      Belgium_PhysicsBelgium_Physics

      1528




      1528




      put on hold as off-topic by Nosrati, Paul Frost, Cesareo, José Carlos Santos, amWhy yesterday


      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.




      put on hold as off-topic by Nosrati, Paul Frost, Cesareo, José Carlos Santos, amWhy yesterday


      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.






















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