How to prove this result somewhat similar to Du Bois-Reymond's Lemma?











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Let $Omega subseteq mathbb{R}^n$ be an open bounded connected set with smooth boundary. Suppose also that for each index $i, j = 1, dots, n$, $f_{ij}$ is a smooth function.




If for every $vin C^1(overline{Omega})$ there holds
$$
int_{partialOmega} sum_{i,j=1}^n f_{ij}v nu^j = 0
$$

where $nu$ denotes the normal vector then can we conclude that $sum_{i,j=1}^n f_{ij}nu^i = 0$ on $partialOmega$?




I tried "flatening out the boundary" near a point and the applying Du Bois-Reymond's lemma. But what I get doesn't actually fulfill all the conditions to use Du Bois-Reymond's lemma.



If someone can think of another approach that's worth trying, I appreciate the input!










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  • Do you use Einstein's summing convention?
    – gerw
    yesterday










  • @gerw Yes! Sorry, I should have mentioned that.
    – MathUser_NotPrime
    yesterday

















up vote
0
down vote

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Let $Omega subseteq mathbb{R}^n$ be an open bounded connected set with smooth boundary. Suppose also that for each index $i, j = 1, dots, n$, $f_{ij}$ is a smooth function.




If for every $vin C^1(overline{Omega})$ there holds
$$
int_{partialOmega} sum_{i,j=1}^n f_{ij}v nu^j = 0
$$

where $nu$ denotes the normal vector then can we conclude that $sum_{i,j=1}^n f_{ij}nu^i = 0$ on $partialOmega$?




I tried "flatening out the boundary" near a point and the applying Du Bois-Reymond's lemma. But what I get doesn't actually fulfill all the conditions to use Du Bois-Reymond's lemma.



If someone can think of another approach that's worth trying, I appreciate the input!










share|cite|improve this question
























  • Do you use Einstein's summing convention?
    – gerw
    yesterday










  • @gerw Yes! Sorry, I should have mentioned that.
    – MathUser_NotPrime
    yesterday















up vote
0
down vote

favorite









up vote
0
down vote

favorite











Let $Omega subseteq mathbb{R}^n$ be an open bounded connected set with smooth boundary. Suppose also that for each index $i, j = 1, dots, n$, $f_{ij}$ is a smooth function.




If for every $vin C^1(overline{Omega})$ there holds
$$
int_{partialOmega} sum_{i,j=1}^n f_{ij}v nu^j = 0
$$

where $nu$ denotes the normal vector then can we conclude that $sum_{i,j=1}^n f_{ij}nu^i = 0$ on $partialOmega$?




I tried "flatening out the boundary" near a point and the applying Du Bois-Reymond's lemma. But what I get doesn't actually fulfill all the conditions to use Du Bois-Reymond's lemma.



If someone can think of another approach that's worth trying, I appreciate the input!










share|cite|improve this question















Let $Omega subseteq mathbb{R}^n$ be an open bounded connected set with smooth boundary. Suppose also that for each index $i, j = 1, dots, n$, $f_{ij}$ is a smooth function.




If for every $vin C^1(overline{Omega})$ there holds
$$
int_{partialOmega} sum_{i,j=1}^n f_{ij}v nu^j = 0
$$

where $nu$ denotes the normal vector then can we conclude that $sum_{i,j=1}^n f_{ij}nu^i = 0$ on $partialOmega$?




I tried "flatening out the boundary" near a point and the applying Du Bois-Reymond's lemma. But what I get doesn't actually fulfill all the conditions to use Du Bois-Reymond's lemma.



If someone can think of another approach that's worth trying, I appreciate the input!







real-analysis functional-analysis lebesgue-integral weak-convergence






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MathUser_NotPrime

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  • Do you use Einstein's summing convention?
    – gerw
    yesterday










  • @gerw Yes! Sorry, I should have mentioned that.
    – MathUser_NotPrime
    yesterday




















  • Do you use Einstein's summing convention?
    – gerw
    yesterday










  • @gerw Yes! Sorry, I should have mentioned that.
    – MathUser_NotPrime
    yesterday


















Do you use Einstein's summing convention?
– gerw
yesterday




Do you use Einstein's summing convention?
– gerw
yesterday












@gerw Yes! Sorry, I should have mentioned that.
– MathUser_NotPrime
yesterday






@gerw Yes! Sorry, I should have mentioned that.
– MathUser_NotPrime
yesterday

















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