Implications with the Lebesgue integral

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Let $(X,mathcalB,mu)$ a probability space and $f:X to mathbbR$ a non negative and integrable function. My question is, for $a>0$,



if $int_Xfdmugeq a$, then there exist a Borel set, $Bin mathcalB$, with $mu(B)>0$ such that $f(x)geq a$, for all $xin B$ ?



Please, help me! Thanks.







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    up vote
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    favorite












    Let $(X,mathcalB,mu)$ a probability space and $f:X to mathbbR$ a non negative and integrable function. My question is, for $a>0$,



    if $int_Xfdmugeq a$, then there exist a Borel set, $Bin mathcalB$, with $mu(B)>0$ such that $f(x)geq a$, for all $xin B$ ?



    Please, help me! Thanks.







    share|cite|improve this question























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      Let $(X,mathcalB,mu)$ a probability space and $f:X to mathbbR$ a non negative and integrable function. My question is, for $a>0$,



      if $int_Xfdmugeq a$, then there exist a Borel set, $Bin mathcalB$, with $mu(B)>0$ such that $f(x)geq a$, for all $xin B$ ?



      Please, help me! Thanks.







      share|cite|improve this question













      Let $(X,mathcalB,mu)$ a probability space and $f:X to mathbbR$ a non negative and integrable function. My question is, for $a>0$,



      if $int_Xfdmugeq a$, then there exist a Borel set, $Bin mathcalB$, with $mu(B)>0$ such that $f(x)geq a$, for all $xin B$ ?



      Please, help me! Thanks.









      share|cite|improve this question












      share|cite|improve this question




      share|cite|improve this question








      edited Jul 21 at 0:06
























      asked Jul 21 at 0:00









      Alex C.

      32




      32




















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          Yes. Take $B=x:f(x) geq a$. If $mu (B)=0$ the $f<a $ almost everywhere which implies $int f , dmu <a$.






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            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            1
            down vote



            accepted










            Yes. Take $B=x:f(x) geq a$. If $mu (B)=0$ the $f<a $ almost everywhere which implies $int f , dmu <a$.






            share|cite|improve this answer

























              up vote
              1
              down vote



              accepted










              Yes. Take $B=x:f(x) geq a$. If $mu (B)=0$ the $f<a $ almost everywhere which implies $int f , dmu <a$.






              share|cite|improve this answer























                up vote
                1
                down vote



                accepted







                up vote
                1
                down vote



                accepted






                Yes. Take $B=x:f(x) geq a$. If $mu (B)=0$ the $f<a $ almost everywhere which implies $int f , dmu <a$.






                share|cite|improve this answer













                Yes. Take $B=x:f(x) geq a$. If $mu (B)=0$ the $f<a $ almost everywhere which implies $int f , dmu <a$.







                share|cite|improve this answer













                share|cite|improve this answer



                share|cite|improve this answer











                answered Jul 21 at 0:15









                Kavi Rama Murthy

                20.6k2830




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