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The set $D_v= xin mathbbR^N: D_vf(x) text exists $ is measurable.


Compute integral of a Lebesgue measurable setOuter measure proof, assuming measurable set existsShow the existence of a Borel measurable function $phi: mathbbR to mathbbR$is the set measurable?Showing that a set is measurableLet $f : E rightarrow mathbbR$. Show that if $|f|$ is measurable on $E$ and the set $f > 0$ is measurable, then $f$ is measurable on $E$.Give an example of a non-Lebesgue measurable function $f:mathbb R to mathbb R $ such that $|f|$ is a measurable function and …Measurable function constant on uncountable setIs the set $A=xin E$ measurable?Let $f$ be defined on a measurable set $E subset mathbb R^n$. If $a<f<+infty$ and $f=-infty$ are measurable, then $f$ is measurable













0












$begingroup$


Let $f:mathbbR^nto mathbbR$ be Lipsticz function. The directional derivative in the direction of $mathbfv$ is given by $$ D_mathbfvf(mathbfx)=lim_tto 0dfracf(mathbfx+tmathbfv)-f(mathbfx)t. $$ Define a set $$ D_mathbfv= mathbfxin mathbbR^n:D_mathbfvf(mathbfx)text exists .$$ Show that $D_mathbfv$ is measurable.



Please help me in proving that.










share|cite|improve this question









$endgroup$











  • $begingroup$
    What have you tried? What do you know? Do you know that $limsup_tto 0 g_t(x)$ of measurable functions for each $t$ is measurable?
    $endgroup$
    – Shashi
    yesterday











  • $begingroup$
    Yes that I know. But how does this help could you please give me some more hint. Then probably I can proceed.
    $endgroup$
    – XYZABC
    yesterday






  • 1




    $begingroup$
    Then the set you are looking for is $x : limsup_tto 0 g_t(x)-liminf_tto 0g_t(x)=0 $ for a suitable chosen $g_t(x)$... Do you get it?
    $endgroup$
    – Shashi
    yesterday










  • $begingroup$
    Okay, I got it. Thanks.
    $endgroup$
    – XYZABC
    yesterday















0












$begingroup$


Let $f:mathbbR^nto mathbbR$ be Lipsticz function. The directional derivative in the direction of $mathbfv$ is given by $$ D_mathbfvf(mathbfx)=lim_tto 0dfracf(mathbfx+tmathbfv)-f(mathbfx)t. $$ Define a set $$ D_mathbfv= mathbfxin mathbbR^n:D_mathbfvf(mathbfx)text exists .$$ Show that $D_mathbfv$ is measurable.



Please help me in proving that.










share|cite|improve this question









$endgroup$











  • $begingroup$
    What have you tried? What do you know? Do you know that $limsup_tto 0 g_t(x)$ of measurable functions for each $t$ is measurable?
    $endgroup$
    – Shashi
    yesterday











  • $begingroup$
    Yes that I know. But how does this help could you please give me some more hint. Then probably I can proceed.
    $endgroup$
    – XYZABC
    yesterday






  • 1




    $begingroup$
    Then the set you are looking for is $x : limsup_tto 0 g_t(x)-liminf_tto 0g_t(x)=0 $ for a suitable chosen $g_t(x)$... Do you get it?
    $endgroup$
    – Shashi
    yesterday










  • $begingroup$
    Okay, I got it. Thanks.
    $endgroup$
    – XYZABC
    yesterday













0












0








0





$begingroup$


Let $f:mathbbR^nto mathbbR$ be Lipsticz function. The directional derivative in the direction of $mathbfv$ is given by $$ D_mathbfvf(mathbfx)=lim_tto 0dfracf(mathbfx+tmathbfv)-f(mathbfx)t. $$ Define a set $$ D_mathbfv= mathbfxin mathbbR^n:D_mathbfvf(mathbfx)text exists .$$ Show that $D_mathbfv$ is measurable.



Please help me in proving that.










share|cite|improve this question









$endgroup$




Let $f:mathbbR^nto mathbbR$ be Lipsticz function. The directional derivative in the direction of $mathbfv$ is given by $$ D_mathbfvf(mathbfx)=lim_tto 0dfracf(mathbfx+tmathbfv)-f(mathbfx)t. $$ Define a set $$ D_mathbfv= mathbfxin mathbbR^n:D_mathbfvf(mathbfx)text exists .$$ Show that $D_mathbfv$ is measurable.



Please help me in proving that.







measure-theory






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked yesterday









XYZABCXYZABC

344110




344110











  • $begingroup$
    What have you tried? What do you know? Do you know that $limsup_tto 0 g_t(x)$ of measurable functions for each $t$ is measurable?
    $endgroup$
    – Shashi
    yesterday











  • $begingroup$
    Yes that I know. But how does this help could you please give me some more hint. Then probably I can proceed.
    $endgroup$
    – XYZABC
    yesterday






  • 1




    $begingroup$
    Then the set you are looking for is $x : limsup_tto 0 g_t(x)-liminf_tto 0g_t(x)=0 $ for a suitable chosen $g_t(x)$... Do you get it?
    $endgroup$
    – Shashi
    yesterday










  • $begingroup$
    Okay, I got it. Thanks.
    $endgroup$
    – XYZABC
    yesterday
















  • $begingroup$
    What have you tried? What do you know? Do you know that $limsup_tto 0 g_t(x)$ of measurable functions for each $t$ is measurable?
    $endgroup$
    – Shashi
    yesterday











  • $begingroup$
    Yes that I know. But how does this help could you please give me some more hint. Then probably I can proceed.
    $endgroup$
    – XYZABC
    yesterday






  • 1




    $begingroup$
    Then the set you are looking for is $x : limsup_tto 0 g_t(x)-liminf_tto 0g_t(x)=0 $ for a suitable chosen $g_t(x)$... Do you get it?
    $endgroup$
    – Shashi
    yesterday










  • $begingroup$
    Okay, I got it. Thanks.
    $endgroup$
    – XYZABC
    yesterday















$begingroup$
What have you tried? What do you know? Do you know that $limsup_tto 0 g_t(x)$ of measurable functions for each $t$ is measurable?
$endgroup$
– Shashi
yesterday





$begingroup$
What have you tried? What do you know? Do you know that $limsup_tto 0 g_t(x)$ of measurable functions for each $t$ is measurable?
$endgroup$
– Shashi
yesterday













$begingroup$
Yes that I know. But how does this help could you please give me some more hint. Then probably I can proceed.
$endgroup$
– XYZABC
yesterday




$begingroup$
Yes that I know. But how does this help could you please give me some more hint. Then probably I can proceed.
$endgroup$
– XYZABC
yesterday




1




1




$begingroup$
Then the set you are looking for is $x : limsup_tto 0 g_t(x)-liminf_tto 0g_t(x)=0 $ for a suitable chosen $g_t(x)$... Do you get it?
$endgroup$
– Shashi
yesterday




$begingroup$
Then the set you are looking for is $x : limsup_tto 0 g_t(x)-liminf_tto 0g_t(x)=0 $ for a suitable chosen $g_t(x)$... Do you get it?
$endgroup$
– Shashi
yesterday












$begingroup$
Okay, I got it. Thanks.
$endgroup$
– XYZABC
yesterday




$begingroup$
Okay, I got it. Thanks.
$endgroup$
– XYZABC
yesterday










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