Does this conclude that $ int_E f_jg_j dx to int_E fgdx$?












1












$begingroup$


Suppose $f_j to f$ strongly in $L^2(E)$ and $g_j to g $ weakly in $L^2(E)$, where $E subset mathbb{R}^d$ is measurable. Show that $ int_Ef_jg_jdx to int_E fgdx$.



Answer:



I am quoting the following theorem:



$text{Product of weak-strong converging sequence}:$



Let $1 < p < infty$, $ u_n: Omega to mathbb{R}$ be a sequence in $L^p(Omega)$, and $u in L^p(Omega)$. Let $v_n: Omega to mathbb{R}$ be a sequence in $L^{p'}(Omega)$, $ frac{1}{p}+frac{1}{p'}=1$. Suppose,



$u_n$ converges to $u$ weakly in $L^p(Omega)$,



$v_n$ converges to $v$ strongly in $L^{p'}(Omega)$,



Then $u_n v_n to uv$ weakly in $L^{1}(Omega)$



This is the theorem.



By applying the above theorem, we get



$f_jg_j$ converges to $fg$ weakly in $L^{1}(Omega)$.



Does this conclude that $ int_E f_jg_j dx to int_E fgdx$?



Help me










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$endgroup$








  • 1




    $begingroup$
    Yes, since $1_E$ is in $(L^1(Omega))^*=L^infty(Omega)$.
    $endgroup$
    – Song
    Jan 21 at 19:31


















1












$begingroup$


Suppose $f_j to f$ strongly in $L^2(E)$ and $g_j to g $ weakly in $L^2(E)$, where $E subset mathbb{R}^d$ is measurable. Show that $ int_Ef_jg_jdx to int_E fgdx$.



Answer:



I am quoting the following theorem:



$text{Product of weak-strong converging sequence}:$



Let $1 < p < infty$, $ u_n: Omega to mathbb{R}$ be a sequence in $L^p(Omega)$, and $u in L^p(Omega)$. Let $v_n: Omega to mathbb{R}$ be a sequence in $L^{p'}(Omega)$, $ frac{1}{p}+frac{1}{p'}=1$. Suppose,



$u_n$ converges to $u$ weakly in $L^p(Omega)$,



$v_n$ converges to $v$ strongly in $L^{p'}(Omega)$,



Then $u_n v_n to uv$ weakly in $L^{1}(Omega)$



This is the theorem.



By applying the above theorem, we get



$f_jg_j$ converges to $fg$ weakly in $L^{1}(Omega)$.



Does this conclude that $ int_E f_jg_j dx to int_E fgdx$?



Help me










share|cite|improve this question









$endgroup$








  • 1




    $begingroup$
    Yes, since $1_E$ is in $(L^1(Omega))^*=L^infty(Omega)$.
    $endgroup$
    – Song
    Jan 21 at 19:31
















1












1








1


1



$begingroup$


Suppose $f_j to f$ strongly in $L^2(E)$ and $g_j to g $ weakly in $L^2(E)$, where $E subset mathbb{R}^d$ is measurable. Show that $ int_Ef_jg_jdx to int_E fgdx$.



Answer:



I am quoting the following theorem:



$text{Product of weak-strong converging sequence}:$



Let $1 < p < infty$, $ u_n: Omega to mathbb{R}$ be a sequence in $L^p(Omega)$, and $u in L^p(Omega)$. Let $v_n: Omega to mathbb{R}$ be a sequence in $L^{p'}(Omega)$, $ frac{1}{p}+frac{1}{p'}=1$. Suppose,



$u_n$ converges to $u$ weakly in $L^p(Omega)$,



$v_n$ converges to $v$ strongly in $L^{p'}(Omega)$,



Then $u_n v_n to uv$ weakly in $L^{1}(Omega)$



This is the theorem.



By applying the above theorem, we get



$f_jg_j$ converges to $fg$ weakly in $L^{1}(Omega)$.



Does this conclude that $ int_E f_jg_j dx to int_E fgdx$?



Help me










share|cite|improve this question









$endgroup$




Suppose $f_j to f$ strongly in $L^2(E)$ and $g_j to g $ weakly in $L^2(E)$, where $E subset mathbb{R}^d$ is measurable. Show that $ int_Ef_jg_jdx to int_E fgdx$.



Answer:



I am quoting the following theorem:



$text{Product of weak-strong converging sequence}:$



Let $1 < p < infty$, $ u_n: Omega to mathbb{R}$ be a sequence in $L^p(Omega)$, and $u in L^p(Omega)$. Let $v_n: Omega to mathbb{R}$ be a sequence in $L^{p'}(Omega)$, $ frac{1}{p}+frac{1}{p'}=1$. Suppose,



$u_n$ converges to $u$ weakly in $L^p(Omega)$,



$v_n$ converges to $v$ strongly in $L^{p'}(Omega)$,



Then $u_n v_n to uv$ weakly in $L^{1}(Omega)$



This is the theorem.



By applying the above theorem, we get



$f_jg_j$ converges to $fg$ weakly in $L^{1}(Omega)$.



Does this conclude that $ int_E f_jg_j dx to int_E fgdx$?



Help me







measure-theory weak-convergence strong-convergence






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asked Jan 21 at 19:15









M. A. SARKARM. A. SARKAR

2,3221719




2,3221719








  • 1




    $begingroup$
    Yes, since $1_E$ is in $(L^1(Omega))^*=L^infty(Omega)$.
    $endgroup$
    – Song
    Jan 21 at 19:31
















  • 1




    $begingroup$
    Yes, since $1_E$ is in $(L^1(Omega))^*=L^infty(Omega)$.
    $endgroup$
    – Song
    Jan 21 at 19:31










1




1




$begingroup$
Yes, since $1_E$ is in $(L^1(Omega))^*=L^infty(Omega)$.
$endgroup$
– Song
Jan 21 at 19:31






$begingroup$
Yes, since $1_E$ is in $(L^1(Omega))^*=L^infty(Omega)$.
$endgroup$
– Song
Jan 21 at 19:31












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Yes: weak convergence of a sequence $ left(h_nright)_{ngeqslant 1}$ in $mathbb L^1$ to a function $h$ means that for each linear continuous functional $Phicolonmathbb L^1tomathbb R$, the sequence $left(Phileft(h_nright)right)_{ngeqslant 1}$ converges to $Phileft(hright)$. This definition is applied to $Phicolon hmapsto int_E h(x)mathrm dx$, which is linear and continuous.






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    $begingroup$

    Yes: weak convergence of a sequence $ left(h_nright)_{ngeqslant 1}$ in $mathbb L^1$ to a function $h$ means that for each linear continuous functional $Phicolonmathbb L^1tomathbb R$, the sequence $left(Phileft(h_nright)right)_{ngeqslant 1}$ converges to $Phileft(hright)$. This definition is applied to $Phicolon hmapsto int_E h(x)mathrm dx$, which is linear and continuous.






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      Yes: weak convergence of a sequence $ left(h_nright)_{ngeqslant 1}$ in $mathbb L^1$ to a function $h$ means that for each linear continuous functional $Phicolonmathbb L^1tomathbb R$, the sequence $left(Phileft(h_nright)right)_{ngeqslant 1}$ converges to $Phileft(hright)$. This definition is applied to $Phicolon hmapsto int_E h(x)mathrm dx$, which is linear and continuous.






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        Yes: weak convergence of a sequence $ left(h_nright)_{ngeqslant 1}$ in $mathbb L^1$ to a function $h$ means that for each linear continuous functional $Phicolonmathbb L^1tomathbb R$, the sequence $left(Phileft(h_nright)right)_{ngeqslant 1}$ converges to $Phileft(hright)$. This definition is applied to $Phicolon hmapsto int_E h(x)mathrm dx$, which is linear and continuous.






        share|cite|improve this answer









        $endgroup$



        Yes: weak convergence of a sequence $ left(h_nright)_{ngeqslant 1}$ in $mathbb L^1$ to a function $h$ means that for each linear continuous functional $Phicolonmathbb L^1tomathbb R$, the sequence $left(Phileft(h_nright)right)_{ngeqslant 1}$ converges to $Phileft(hright)$. This definition is applied to $Phicolon hmapsto int_E h(x)mathrm dx$, which is linear and continuous.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 21 at 22:20









        Davide GiraudoDavide Giraudo

        127k17154268




        127k17154268






























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