Hadamard theorem about embedding











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The following theorem is commonly attributed to Hadamard.




Assume $Sigma$ is a smooth locally convex immersed surface in the Euclidean space. Then $Sigma$ is embedded and bounds a convex set.




Many authors refer to Hadamard's Sur certaines propriétés des trajectoires en Dynamique (1897)
(for example, J.J.Stoker in his Über die Gestalt der positiv... (1936)).



Likely the statement is there, but the paper is long, it is in French and often the statements are not clearly marked; I was searching for it for several days. I asked a friend and she said that it was there 20 years ago, but she could not find it; she also said that it was not easy to extract it from what is written ( = one has to think). [For sure the word immersion is not there.]



I hope someone here knows this paper and can help me.










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  • 1




    To remain in the spirit of this site, a present-day referee would probably tell Hadamard : "unclear what you're claiming" !
    – Sylvain JULIEN
    yesterday















up vote
12
down vote

favorite
2












The following theorem is commonly attributed to Hadamard.




Assume $Sigma$ is a smooth locally convex immersed surface in the Euclidean space. Then $Sigma$ is embedded and bounds a convex set.




Many authors refer to Hadamard's Sur certaines propriétés des trajectoires en Dynamique (1897)
(for example, J.J.Stoker in his Über die Gestalt der positiv... (1936)).



Likely the statement is there, but the paper is long, it is in French and often the statements are not clearly marked; I was searching for it for several days. I asked a friend and she said that it was there 20 years ago, but she could not find it; she also said that it was not easy to extract it from what is written ( = one has to think). [For sure the word immersion is not there.]



I hope someone here knows this paper and can help me.










share|cite|improve this question




















  • 1




    To remain in the spirit of this site, a present-day referee would probably tell Hadamard : "unclear what you're claiming" !
    – Sylvain JULIEN
    yesterday













up vote
12
down vote

favorite
2









up vote
12
down vote

favorite
2






2





The following theorem is commonly attributed to Hadamard.




Assume $Sigma$ is a smooth locally convex immersed surface in the Euclidean space. Then $Sigma$ is embedded and bounds a convex set.




Many authors refer to Hadamard's Sur certaines propriétés des trajectoires en Dynamique (1897)
(for example, J.J.Stoker in his Über die Gestalt der positiv... (1936)).



Likely the statement is there, but the paper is long, it is in French and often the statements are not clearly marked; I was searching for it for several days. I asked a friend and she said that it was there 20 years ago, but she could not find it; she also said that it was not easy to extract it from what is written ( = one has to think). [For sure the word immersion is not there.]



I hope someone here knows this paper and can help me.










share|cite|improve this question















The following theorem is commonly attributed to Hadamard.




Assume $Sigma$ is a smooth locally convex immersed surface in the Euclidean space. Then $Sigma$ is embedded and bounds a convex set.




Many authors refer to Hadamard's Sur certaines propriétés des trajectoires en Dynamique (1897)
(for example, J.J.Stoker in his Über die Gestalt der positiv... (1936)).



Likely the statement is there, but the paper is long, it is in French and often the statements are not clearly marked; I was searching for it for several days. I asked a friend and she said that it was there 20 years ago, but she could not find it; she also said that it was not easy to extract it from what is written ( = one has to think). [For sure the word immersion is not there.]



I hope someone here knows this paper and can help me.







reference-request dg.differential-geometry curves-and-surfaces surfaces






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edited 23 hours ago

























asked yesterday









Anton Petrunin

26.2k578196




26.2k578196








  • 1




    To remain in the spirit of this site, a present-day referee would probably tell Hadamard : "unclear what you're claiming" !
    – Sylvain JULIEN
    yesterday














  • 1




    To remain in the spirit of this site, a present-day referee would probably tell Hadamard : "unclear what you're claiming" !
    – Sylvain JULIEN
    yesterday








1




1




To remain in the spirit of this site, a present-day referee would probably tell Hadamard : "unclear what you're claiming" !
– Sylvain JULIEN
yesterday




To remain in the spirit of this site, a present-day referee would probably tell Hadamard : "unclear what you're claiming" !
– Sylvain JULIEN
yesterday










1 Answer
1






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oldest

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up vote
8
down vote



accepted










I think the relevant location is item 23, page 352, but what Hadamard aims to is stated as follows:




A smooth, co-orientable surface of $mathbb{R}^3$ with Gauss curvature bounded below by some $kappa >0$ is simply connected. (implicitly, the surface is compact without boundary)




("Or une surface à deux côtés et sans points singuliers, à courbure partout positive (la valeur zéro et les valeurs infiniment petites étant exclues) est toujours simplement connexe.")



The goal is to use the Gauss-Bonnet Formula to deduce that when curvature is positive, any two closed geodesics must meet (otherwise they would together bound a total curvature 0 region of the surface).



What is not clear from the text of item 23 is whether the surface assumed to be immersed or embedded. He basically says that the normal map is a global diffeomorphism, because positive curvature makes it a covering of the sphere. It seems the argument does provide the statement attributed to this paper, although it seems not explicitly stated.






share|cite|improve this answer





















  • The arguments in 23 do not seem to show that immersed sphere is embedded, even informally; am I wrong? [I see also pictures on page 379 which are relevant to a proof I know, but the words around these pictures seem to be irrelevant.]
    – Anton Petrunin
    yesterday












  • @AntonPetrunin you are probably right but I do not have much time checking in details. I would not be surprised, given the informality of the discussion, if the attribution of this statement would be somewhat of a stretch. In any case, I do not think it was the point Hadamard wanted to make (and he might assume the embedding in the first place).
    – Benoît Kloeckner
    15 hours ago











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1 Answer
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up vote
8
down vote



accepted










I think the relevant location is item 23, page 352, but what Hadamard aims to is stated as follows:




A smooth, co-orientable surface of $mathbb{R}^3$ with Gauss curvature bounded below by some $kappa >0$ is simply connected. (implicitly, the surface is compact without boundary)




("Or une surface à deux côtés et sans points singuliers, à courbure partout positive (la valeur zéro et les valeurs infiniment petites étant exclues) est toujours simplement connexe.")



The goal is to use the Gauss-Bonnet Formula to deduce that when curvature is positive, any two closed geodesics must meet (otherwise they would together bound a total curvature 0 region of the surface).



What is not clear from the text of item 23 is whether the surface assumed to be immersed or embedded. He basically says that the normal map is a global diffeomorphism, because positive curvature makes it a covering of the sphere. It seems the argument does provide the statement attributed to this paper, although it seems not explicitly stated.






share|cite|improve this answer





















  • The arguments in 23 do not seem to show that immersed sphere is embedded, even informally; am I wrong? [I see also pictures on page 379 which are relevant to a proof I know, but the words around these pictures seem to be irrelevant.]
    – Anton Petrunin
    yesterday












  • @AntonPetrunin you are probably right but I do not have much time checking in details. I would not be surprised, given the informality of the discussion, if the attribution of this statement would be somewhat of a stretch. In any case, I do not think it was the point Hadamard wanted to make (and he might assume the embedding in the first place).
    – Benoît Kloeckner
    15 hours ago















up vote
8
down vote



accepted










I think the relevant location is item 23, page 352, but what Hadamard aims to is stated as follows:




A smooth, co-orientable surface of $mathbb{R}^3$ with Gauss curvature bounded below by some $kappa >0$ is simply connected. (implicitly, the surface is compact without boundary)




("Or une surface à deux côtés et sans points singuliers, à courbure partout positive (la valeur zéro et les valeurs infiniment petites étant exclues) est toujours simplement connexe.")



The goal is to use the Gauss-Bonnet Formula to deduce that when curvature is positive, any two closed geodesics must meet (otherwise they would together bound a total curvature 0 region of the surface).



What is not clear from the text of item 23 is whether the surface assumed to be immersed or embedded. He basically says that the normal map is a global diffeomorphism, because positive curvature makes it a covering of the sphere. It seems the argument does provide the statement attributed to this paper, although it seems not explicitly stated.






share|cite|improve this answer





















  • The arguments in 23 do not seem to show that immersed sphere is embedded, even informally; am I wrong? [I see also pictures on page 379 which are relevant to a proof I know, but the words around these pictures seem to be irrelevant.]
    – Anton Petrunin
    yesterday












  • @AntonPetrunin you are probably right but I do not have much time checking in details. I would not be surprised, given the informality of the discussion, if the attribution of this statement would be somewhat of a stretch. In any case, I do not think it was the point Hadamard wanted to make (and he might assume the embedding in the first place).
    – Benoît Kloeckner
    15 hours ago













up vote
8
down vote



accepted







up vote
8
down vote



accepted






I think the relevant location is item 23, page 352, but what Hadamard aims to is stated as follows:




A smooth, co-orientable surface of $mathbb{R}^3$ with Gauss curvature bounded below by some $kappa >0$ is simply connected. (implicitly, the surface is compact without boundary)




("Or une surface à deux côtés et sans points singuliers, à courbure partout positive (la valeur zéro et les valeurs infiniment petites étant exclues) est toujours simplement connexe.")



The goal is to use the Gauss-Bonnet Formula to deduce that when curvature is positive, any two closed geodesics must meet (otherwise they would together bound a total curvature 0 region of the surface).



What is not clear from the text of item 23 is whether the surface assumed to be immersed or embedded. He basically says that the normal map is a global diffeomorphism, because positive curvature makes it a covering of the sphere. It seems the argument does provide the statement attributed to this paper, although it seems not explicitly stated.






share|cite|improve this answer












I think the relevant location is item 23, page 352, but what Hadamard aims to is stated as follows:




A smooth, co-orientable surface of $mathbb{R}^3$ with Gauss curvature bounded below by some $kappa >0$ is simply connected. (implicitly, the surface is compact without boundary)




("Or une surface à deux côtés et sans points singuliers, à courbure partout positive (la valeur zéro et les valeurs infiniment petites étant exclues) est toujours simplement connexe.")



The goal is to use the Gauss-Bonnet Formula to deduce that when curvature is positive, any two closed geodesics must meet (otherwise they would together bound a total curvature 0 region of the surface).



What is not clear from the text of item 23 is whether the surface assumed to be immersed or embedded. He basically says that the normal map is a global diffeomorphism, because positive curvature makes it a covering of the sphere. It seems the argument does provide the statement attributed to this paper, although it seems not explicitly stated.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered yesterday









Benoît Kloeckner

10.8k14382




10.8k14382












  • The arguments in 23 do not seem to show that immersed sphere is embedded, even informally; am I wrong? [I see also pictures on page 379 which are relevant to a proof I know, but the words around these pictures seem to be irrelevant.]
    – Anton Petrunin
    yesterday












  • @AntonPetrunin you are probably right but I do not have much time checking in details. I would not be surprised, given the informality of the discussion, if the attribution of this statement would be somewhat of a stretch. In any case, I do not think it was the point Hadamard wanted to make (and he might assume the embedding in the first place).
    – Benoît Kloeckner
    15 hours ago


















  • The arguments in 23 do not seem to show that immersed sphere is embedded, even informally; am I wrong? [I see also pictures on page 379 which are relevant to a proof I know, but the words around these pictures seem to be irrelevant.]
    – Anton Petrunin
    yesterday












  • @AntonPetrunin you are probably right but I do not have much time checking in details. I would not be surprised, given the informality of the discussion, if the attribution of this statement would be somewhat of a stretch. In any case, I do not think it was the point Hadamard wanted to make (and he might assume the embedding in the first place).
    – Benoît Kloeckner
    15 hours ago
















The arguments in 23 do not seem to show that immersed sphere is embedded, even informally; am I wrong? [I see also pictures on page 379 which are relevant to a proof I know, but the words around these pictures seem to be irrelevant.]
– Anton Petrunin
yesterday






The arguments in 23 do not seem to show that immersed sphere is embedded, even informally; am I wrong? [I see also pictures on page 379 which are relevant to a proof I know, but the words around these pictures seem to be irrelevant.]
– Anton Petrunin
yesterday














@AntonPetrunin you are probably right but I do not have much time checking in details. I would not be surprised, given the informality of the discussion, if the attribution of this statement would be somewhat of a stretch. In any case, I do not think it was the point Hadamard wanted to make (and he might assume the embedding in the first place).
– Benoît Kloeckner
15 hours ago




@AntonPetrunin you are probably right but I do not have much time checking in details. I would not be surprised, given the informality of the discussion, if the attribution of this statement would be somewhat of a stretch. In any case, I do not think it was the point Hadamard wanted to make (and he might assume the embedding in the first place).
– Benoît Kloeckner
15 hours ago


















 

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