Differential 1-form of line
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This problem is from V.I Arnold's book Mathematics of Classical Mechanics.
Q) Show that every differential 1-form on line is differential of some function
- Relevant equations
The differential of any function is
$$df_{x}(psi): TM_{x} rightarrow R$$
- The attempt at a solution
The tangent to line is line itself. The differential 1-form is $dy-dx=0$. Here I am struct. I don't know how to find out the differential. Can anyone help?
differential-geometry differential-forms
$endgroup$
add a comment |
$begingroup$
This problem is from V.I Arnold's book Mathematics of Classical Mechanics.
Q) Show that every differential 1-form on line is differential of some function
- Relevant equations
The differential of any function is
$$df_{x}(psi): TM_{x} rightarrow R$$
- The attempt at a solution
The tangent to line is line itself. The differential 1-form is $dy-dx=0$. Here I am struct. I don't know how to find out the differential. Can anyone help?
differential-geometry differential-forms
$endgroup$
$begingroup$
If you consider $omega(x)dx$ as the differential form, what can you say about $f(x):=int_0^x omega(t)dt$?
$endgroup$
– Gabriele Cassese
Feb 1 at 15:57
$begingroup$
$dy-dx$ is not a differential form on the line, it is a differential form on the plane
$endgroup$
– Gabriele Cassese
Feb 3 at 15:15
add a comment |
$begingroup$
This problem is from V.I Arnold's book Mathematics of Classical Mechanics.
Q) Show that every differential 1-form on line is differential of some function
- Relevant equations
The differential of any function is
$$df_{x}(psi): TM_{x} rightarrow R$$
- The attempt at a solution
The tangent to line is line itself. The differential 1-form is $dy-dx=0$. Here I am struct. I don't know how to find out the differential. Can anyone help?
differential-geometry differential-forms
$endgroup$
This problem is from V.I Arnold's book Mathematics of Classical Mechanics.
Q) Show that every differential 1-form on line is differential of some function
- Relevant equations
The differential of any function is
$$df_{x}(psi): TM_{x} rightarrow R$$
- The attempt at a solution
The tangent to line is line itself. The differential 1-form is $dy-dx=0$. Here I am struct. I don't know how to find out the differential. Can anyone help?
differential-geometry differential-forms
differential-geometry differential-forms
asked Feb 1 at 15:41


Abhi7731756Abhi7731756
94
94
$begingroup$
If you consider $omega(x)dx$ as the differential form, what can you say about $f(x):=int_0^x omega(t)dt$?
$endgroup$
– Gabriele Cassese
Feb 1 at 15:57
$begingroup$
$dy-dx$ is not a differential form on the line, it is a differential form on the plane
$endgroup$
– Gabriele Cassese
Feb 3 at 15:15
add a comment |
$begingroup$
If you consider $omega(x)dx$ as the differential form, what can you say about $f(x):=int_0^x omega(t)dt$?
$endgroup$
– Gabriele Cassese
Feb 1 at 15:57
$begingroup$
$dy-dx$ is not a differential form on the line, it is a differential form on the plane
$endgroup$
– Gabriele Cassese
Feb 3 at 15:15
$begingroup$
If you consider $omega(x)dx$ as the differential form, what can you say about $f(x):=int_0^x omega(t)dt$?
$endgroup$
– Gabriele Cassese
Feb 1 at 15:57
$begingroup$
If you consider $omega(x)dx$ as the differential form, what can you say about $f(x):=int_0^x omega(t)dt$?
$endgroup$
– Gabriele Cassese
Feb 1 at 15:57
$begingroup$
$dy-dx$ is not a differential form on the line, it is a differential form on the plane
$endgroup$
– Gabriele Cassese
Feb 3 at 15:15
$begingroup$
$dy-dx$ is not a differential form on the line, it is a differential form on the plane
$endgroup$
– Gabriele Cassese
Feb 3 at 15:15
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
$dy-dx$ is not a differential form on $mathbb{R}$, since $mathbb{R}$ has only one coordinate for every chart you choose.
It is instead a differential form on $mathbb{R}^2$, where is the differential of
$f(x,y)=y-x$.
About Arnold's exercise, I would insted prove it in this way:
Let $omega(x)dx $ be the general differential form on $mathbb{R}$, where $omega(x)$ is $C^{infty}[mathbb{R}]$. Then, let $f:=int_0^xomega(t)dt$. By definition of differential and by the fundamental theorem of calculus, we obtain that:
$df=partial_{x}( int_0^x omega(t)dt)dx=omega(x)dx$
QED
$endgroup$
$begingroup$
@Abhi7731756 Is there anything wrong or unclear with the answer?
$endgroup$
– Gabriele Cassese
Feb 4 at 20:43
add a comment |
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1 Answer
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1 Answer
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active
oldest
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active
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votes
active
oldest
votes
$begingroup$
$dy-dx$ is not a differential form on $mathbb{R}$, since $mathbb{R}$ has only one coordinate for every chart you choose.
It is instead a differential form on $mathbb{R}^2$, where is the differential of
$f(x,y)=y-x$.
About Arnold's exercise, I would insted prove it in this way:
Let $omega(x)dx $ be the general differential form on $mathbb{R}$, where $omega(x)$ is $C^{infty}[mathbb{R}]$. Then, let $f:=int_0^xomega(t)dt$. By definition of differential and by the fundamental theorem of calculus, we obtain that:
$df=partial_{x}( int_0^x omega(t)dt)dx=omega(x)dx$
QED
$endgroup$
$begingroup$
@Abhi7731756 Is there anything wrong or unclear with the answer?
$endgroup$
– Gabriele Cassese
Feb 4 at 20:43
add a comment |
$begingroup$
$dy-dx$ is not a differential form on $mathbb{R}$, since $mathbb{R}$ has only one coordinate for every chart you choose.
It is instead a differential form on $mathbb{R}^2$, where is the differential of
$f(x,y)=y-x$.
About Arnold's exercise, I would insted prove it in this way:
Let $omega(x)dx $ be the general differential form on $mathbb{R}$, where $omega(x)$ is $C^{infty}[mathbb{R}]$. Then, let $f:=int_0^xomega(t)dt$. By definition of differential and by the fundamental theorem of calculus, we obtain that:
$df=partial_{x}( int_0^x omega(t)dt)dx=omega(x)dx$
QED
$endgroup$
$begingroup$
@Abhi7731756 Is there anything wrong or unclear with the answer?
$endgroup$
– Gabriele Cassese
Feb 4 at 20:43
add a comment |
$begingroup$
$dy-dx$ is not a differential form on $mathbb{R}$, since $mathbb{R}$ has only one coordinate for every chart you choose.
It is instead a differential form on $mathbb{R}^2$, where is the differential of
$f(x,y)=y-x$.
About Arnold's exercise, I would insted prove it in this way:
Let $omega(x)dx $ be the general differential form on $mathbb{R}$, where $omega(x)$ is $C^{infty}[mathbb{R}]$. Then, let $f:=int_0^xomega(t)dt$. By definition of differential and by the fundamental theorem of calculus, we obtain that:
$df=partial_{x}( int_0^x omega(t)dt)dx=omega(x)dx$
QED
$endgroup$
$dy-dx$ is not a differential form on $mathbb{R}$, since $mathbb{R}$ has only one coordinate for every chart you choose.
It is instead a differential form on $mathbb{R}^2$, where is the differential of
$f(x,y)=y-x$.
About Arnold's exercise, I would insted prove it in this way:
Let $omega(x)dx $ be the general differential form on $mathbb{R}$, where $omega(x)$ is $C^{infty}[mathbb{R}]$. Then, let $f:=int_0^xomega(t)dt$. By definition of differential and by the fundamental theorem of calculus, we obtain that:
$df=partial_{x}( int_0^x omega(t)dt)dx=omega(x)dx$
QED
edited Feb 3 at 15:34
answered Feb 3 at 14:47
Gabriele CasseseGabriele Cassese
1,211316
1,211316
$begingroup$
@Abhi7731756 Is there anything wrong or unclear with the answer?
$endgroup$
– Gabriele Cassese
Feb 4 at 20:43
add a comment |
$begingroup$
@Abhi7731756 Is there anything wrong or unclear with the answer?
$endgroup$
– Gabriele Cassese
Feb 4 at 20:43
$begingroup$
@Abhi7731756 Is there anything wrong or unclear with the answer?
$endgroup$
– Gabriele Cassese
Feb 4 at 20:43
$begingroup$
@Abhi7731756 Is there anything wrong or unclear with the answer?
$endgroup$
– Gabriele Cassese
Feb 4 at 20:43
add a comment |
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$begingroup$
If you consider $omega(x)dx$ as the differential form, what can you say about $f(x):=int_0^x omega(t)dt$?
$endgroup$
– Gabriele Cassese
Feb 1 at 15:57
$begingroup$
$dy-dx$ is not a differential form on the line, it is a differential form on the plane
$endgroup$
– Gabriele Cassese
Feb 3 at 15:15