Tight upper bound on the expectation of a concave function












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N is a random variable whose sample space is $[0,infty)$. I have an expression in terms of the expectation of this variable and I want to find a tight upper bound on the whole expression. The expression is as below:



$1-gamma E[frac{(N+1)}{(1+bcdot N+gamma cdot N+b+gamma)}]$ where $gamma >0$ and $b>0$



I don't know the distribution of N but assuming that I know the $E[N]$, can a tight bound be established on the above expression? If so, can you please refer me to theorems/inequalities that would help me find it?
I looked at Jensen's inequality but it provides a lower bound since the expression over which the expectation is being taken is concave.



(This expression is actually a bound on the probability mass for a subset of the sample space but I don't know the distribution.)



PS: I have asked this question on other platforms but haven't received any answers.










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    $begingroup$


    N is a random variable whose sample space is $[0,infty)$. I have an expression in terms of the expectation of this variable and I want to find a tight upper bound on the whole expression. The expression is as below:



    $1-gamma E[frac{(N+1)}{(1+bcdot N+gamma cdot N+b+gamma)}]$ where $gamma >0$ and $b>0$



    I don't know the distribution of N but assuming that I know the $E[N]$, can a tight bound be established on the above expression? If so, can you please refer me to theorems/inequalities that would help me find it?
    I looked at Jensen's inequality but it provides a lower bound since the expression over which the expectation is being taken is concave.



    (This expression is actually a bound on the probability mass for a subset of the sample space but I don't know the distribution.)



    PS: I have asked this question on other platforms but haven't received any answers.










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      N is a random variable whose sample space is $[0,infty)$. I have an expression in terms of the expectation of this variable and I want to find a tight upper bound on the whole expression. The expression is as below:



      $1-gamma E[frac{(N+1)}{(1+bcdot N+gamma cdot N+b+gamma)}]$ where $gamma >0$ and $b>0$



      I don't know the distribution of N but assuming that I know the $E[N]$, can a tight bound be established on the above expression? If so, can you please refer me to theorems/inequalities that would help me find it?
      I looked at Jensen's inequality but it provides a lower bound since the expression over which the expectation is being taken is concave.



      (This expression is actually a bound on the probability mass for a subset of the sample space but I don't know the distribution.)



      PS: I have asked this question on other platforms but haven't received any answers.










      share|cite|improve this question











      $endgroup$




      N is a random variable whose sample space is $[0,infty)$. I have an expression in terms of the expectation of this variable and I want to find a tight upper bound on the whole expression. The expression is as below:



      $1-gamma E[frac{(N+1)}{(1+bcdot N+gamma cdot N+b+gamma)}]$ where $gamma >0$ and $b>0$



      I don't know the distribution of N but assuming that I know the $E[N]$, can a tight bound be established on the above expression? If so, can you please refer me to theorems/inequalities that would help me find it?
      I looked at Jensen's inequality but it provides a lower bound since the expression over which the expectation is being taken is concave.



      (This expression is actually a bound on the probability mass for a subset of the sample space but I don't know the distribution.)



      PS: I have asked this question on other platforms but haven't received any answers.







      expected-value






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      edited Dec 6 '18 at 5:37









      Tianlalu

      3,08121038




      3,08121038










      asked Dec 6 '18 at 4:38









      gagansogaganso

      155211




      155211






















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