Continuity of integral of indicator function












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I am trying to prove the existence of an equilibrium by applying Brouwer's fixed point theorem. In order to invoke this, I of course need my function to be continuous. The only missing step is finding out whether or not this integral is continuous in c on the intervall [0,1]:



$$p_A = int_{0}^{frac{1}{2}} frac{c}{lambda x + (1-lambda)} mathbb{1} (c in [0, lambda x + (1-lambda)]) mathop{}mathrm{ d} F(x),$$



where $x$ follows an atomless, continuous distribution F(x) on [0,1], and $lambda in [0,1]$.



Can somebody help?










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    0












    $begingroup$


    I am trying to prove the existence of an equilibrium by applying Brouwer's fixed point theorem. In order to invoke this, I of course need my function to be continuous. The only missing step is finding out whether or not this integral is continuous in c on the intervall [0,1]:



    $$p_A = int_{0}^{frac{1}{2}} frac{c}{lambda x + (1-lambda)} mathbb{1} (c in [0, lambda x + (1-lambda)]) mathop{}mathrm{ d} F(x),$$



    where $x$ follows an atomless, continuous distribution F(x) on [0,1], and $lambda in [0,1]$.



    Can somebody help?










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      I am trying to prove the existence of an equilibrium by applying Brouwer's fixed point theorem. In order to invoke this, I of course need my function to be continuous. The only missing step is finding out whether or not this integral is continuous in c on the intervall [0,1]:



      $$p_A = int_{0}^{frac{1}{2}} frac{c}{lambda x + (1-lambda)} mathbb{1} (c in [0, lambda x + (1-lambda)]) mathop{}mathrm{ d} F(x),$$



      where $x$ follows an atomless, continuous distribution F(x) on [0,1], and $lambda in [0,1]$.



      Can somebody help?










      share|cite|improve this question









      $endgroup$




      I am trying to prove the existence of an equilibrium by applying Brouwer's fixed point theorem. In order to invoke this, I of course need my function to be continuous. The only missing step is finding out whether or not this integral is continuous in c on the intervall [0,1]:



      $$p_A = int_{0}^{frac{1}{2}} frac{c}{lambda x + (1-lambda)} mathbb{1} (c in [0, lambda x + (1-lambda)]) mathop{}mathrm{ d} F(x),$$



      where $x$ follows an atomless, continuous distribution F(x) on [0,1], and $lambda in [0,1]$.



      Can somebody help?







      real-analysis integration functions continuity fixed-point-theorems






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      asked Jan 11 at 22:54









      user509037user509037

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          By DCT it is enough to show that if $c_n to c$ then $frac {c_n} {lambda x+(1-lambda)} I_{0leq {c_n} leq lambda x+(1-lambda)} to frac c {lambda x+(1-lambda)} I_{0leq c leq lambda x+(1-lambda)} $ for almost all $x$. Note that this convergence holds if $0<c<lambda x+(1-lambda)$. Since $c=lambda x+(1-lambda)$ for at most one value of $x$ and $F$ is atomless we have completed the proof when $c>0$. The case $c=0$ is much simpler. [Finiteness of $p_A$ is required. If $lambda <1$ then $lambda x+(1-lambda)geq (1-lambda)$ which makes the finiteness obvious. If $lambda =1$ and $cneq 0$ note that $int_c^{1/2} frac 1 x dF(x) <infty$].






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            $begingroup$

            By DCT it is enough to show that if $c_n to c$ then $frac {c_n} {lambda x+(1-lambda)} I_{0leq {c_n} leq lambda x+(1-lambda)} to frac c {lambda x+(1-lambda)} I_{0leq c leq lambda x+(1-lambda)} $ for almost all $x$. Note that this convergence holds if $0<c<lambda x+(1-lambda)$. Since $c=lambda x+(1-lambda)$ for at most one value of $x$ and $F$ is atomless we have completed the proof when $c>0$. The case $c=0$ is much simpler. [Finiteness of $p_A$ is required. If $lambda <1$ then $lambda x+(1-lambda)geq (1-lambda)$ which makes the finiteness obvious. If $lambda =1$ and $cneq 0$ note that $int_c^{1/2} frac 1 x dF(x) <infty$].






            share|cite|improve this answer











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              1












              $begingroup$

              By DCT it is enough to show that if $c_n to c$ then $frac {c_n} {lambda x+(1-lambda)} I_{0leq {c_n} leq lambda x+(1-lambda)} to frac c {lambda x+(1-lambda)} I_{0leq c leq lambda x+(1-lambda)} $ for almost all $x$. Note that this convergence holds if $0<c<lambda x+(1-lambda)$. Since $c=lambda x+(1-lambda)$ for at most one value of $x$ and $F$ is atomless we have completed the proof when $c>0$. The case $c=0$ is much simpler. [Finiteness of $p_A$ is required. If $lambda <1$ then $lambda x+(1-lambda)geq (1-lambda)$ which makes the finiteness obvious. If $lambda =1$ and $cneq 0$ note that $int_c^{1/2} frac 1 x dF(x) <infty$].






              share|cite|improve this answer











              $endgroup$
















                1












                1








                1





                $begingroup$

                By DCT it is enough to show that if $c_n to c$ then $frac {c_n} {lambda x+(1-lambda)} I_{0leq {c_n} leq lambda x+(1-lambda)} to frac c {lambda x+(1-lambda)} I_{0leq c leq lambda x+(1-lambda)} $ for almost all $x$. Note that this convergence holds if $0<c<lambda x+(1-lambda)$. Since $c=lambda x+(1-lambda)$ for at most one value of $x$ and $F$ is atomless we have completed the proof when $c>0$. The case $c=0$ is much simpler. [Finiteness of $p_A$ is required. If $lambda <1$ then $lambda x+(1-lambda)geq (1-lambda)$ which makes the finiteness obvious. If $lambda =1$ and $cneq 0$ note that $int_c^{1/2} frac 1 x dF(x) <infty$].






                share|cite|improve this answer











                $endgroup$



                By DCT it is enough to show that if $c_n to c$ then $frac {c_n} {lambda x+(1-lambda)} I_{0leq {c_n} leq lambda x+(1-lambda)} to frac c {lambda x+(1-lambda)} I_{0leq c leq lambda x+(1-lambda)} $ for almost all $x$. Note that this convergence holds if $0<c<lambda x+(1-lambda)$. Since $c=lambda x+(1-lambda)$ for at most one value of $x$ and $F$ is atomless we have completed the proof when $c>0$. The case $c=0$ is much simpler. [Finiteness of $p_A$ is required. If $lambda <1$ then $lambda x+(1-lambda)geq (1-lambda)$ which makes the finiteness obvious. If $lambda =1$ and $cneq 0$ note that $int_c^{1/2} frac 1 x dF(x) <infty$].







                share|cite|improve this answer














                share|cite|improve this answer



                share|cite|improve this answer








                edited Jan 11 at 23:27

























                answered Jan 11 at 23:18









                Kavi Rama MurthyKavi Rama Murthy

                66.3k42867




                66.3k42867






























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