What makes a Lie Group a Differentiable Manifold?












1














I've recently been trying to glance at the definition of a Lie group, but I'm not clear as to why a Lie group is defined the way it is, and why this becomes a smooth manifold. For example, if we have a Lie group $G$, why do we have the requirement that $G times G to G$, $(x,y) mapsto xy^{-1}$ is a smooth continuous mapping between the product manifold and the manifold $G$.



What is it that makes $G$ a topological manifold in the first place? How does it inherit differentiable structure?










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  • 13




    It's part of the definition!
    – Zhen Lin
    Jul 16 '14 at 21:22










  • You have a set. On that set, you have a group structure, and a differentiable structure. If the two structures play together nicely, it is a Lie group.
    – Daniel Fischer
    Jul 16 '14 at 21:23










  • This isn't a theorem, it's one of the Lie group axioms.
    – Adam Hughes
    Jul 16 '14 at 21:24










  • @DanielFischer But is it Hausdorff and Locally Homeomorphic to Euclidean space? If so, why?
    – Anthony Peter
    Jul 16 '14 at 21:25






  • 3




    @AnthonyPeter: I'd recommend doing some reading about topological groups in general.
    – Kyle
    Jul 16 '14 at 21:27
















1














I've recently been trying to glance at the definition of a Lie group, but I'm not clear as to why a Lie group is defined the way it is, and why this becomes a smooth manifold. For example, if we have a Lie group $G$, why do we have the requirement that $G times G to G$, $(x,y) mapsto xy^{-1}$ is a smooth continuous mapping between the product manifold and the manifold $G$.



What is it that makes $G$ a topological manifold in the first place? How does it inherit differentiable structure?










share|cite|improve this question


















  • 13




    It's part of the definition!
    – Zhen Lin
    Jul 16 '14 at 21:22










  • You have a set. On that set, you have a group structure, and a differentiable structure. If the two structures play together nicely, it is a Lie group.
    – Daniel Fischer
    Jul 16 '14 at 21:23










  • This isn't a theorem, it's one of the Lie group axioms.
    – Adam Hughes
    Jul 16 '14 at 21:24










  • @DanielFischer But is it Hausdorff and Locally Homeomorphic to Euclidean space? If so, why?
    – Anthony Peter
    Jul 16 '14 at 21:25






  • 3




    @AnthonyPeter: I'd recommend doing some reading about topological groups in general.
    – Kyle
    Jul 16 '14 at 21:27














1












1








1







I've recently been trying to glance at the definition of a Lie group, but I'm not clear as to why a Lie group is defined the way it is, and why this becomes a smooth manifold. For example, if we have a Lie group $G$, why do we have the requirement that $G times G to G$, $(x,y) mapsto xy^{-1}$ is a smooth continuous mapping between the product manifold and the manifold $G$.



What is it that makes $G$ a topological manifold in the first place? How does it inherit differentiable structure?










share|cite|improve this question













I've recently been trying to glance at the definition of a Lie group, but I'm not clear as to why a Lie group is defined the way it is, and why this becomes a smooth manifold. For example, if we have a Lie group $G$, why do we have the requirement that $G times G to G$, $(x,y) mapsto xy^{-1}$ is a smooth continuous mapping between the product manifold and the manifold $G$.



What is it that makes $G$ a topological manifold in the first place? How does it inherit differentiable structure?







differential-geometry differential-topology lie-groups lie-algebras






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asked Jul 16 '14 at 21:19









Anthony Peter

3,23211451




3,23211451








  • 13




    It's part of the definition!
    – Zhen Lin
    Jul 16 '14 at 21:22










  • You have a set. On that set, you have a group structure, and a differentiable structure. If the two structures play together nicely, it is a Lie group.
    – Daniel Fischer
    Jul 16 '14 at 21:23










  • This isn't a theorem, it's one of the Lie group axioms.
    – Adam Hughes
    Jul 16 '14 at 21:24










  • @DanielFischer But is it Hausdorff and Locally Homeomorphic to Euclidean space? If so, why?
    – Anthony Peter
    Jul 16 '14 at 21:25






  • 3




    @AnthonyPeter: I'd recommend doing some reading about topological groups in general.
    – Kyle
    Jul 16 '14 at 21:27














  • 13




    It's part of the definition!
    – Zhen Lin
    Jul 16 '14 at 21:22










  • You have a set. On that set, you have a group structure, and a differentiable structure. If the two structures play together nicely, it is a Lie group.
    – Daniel Fischer
    Jul 16 '14 at 21:23










  • This isn't a theorem, it's one of the Lie group axioms.
    – Adam Hughes
    Jul 16 '14 at 21:24










  • @DanielFischer But is it Hausdorff and Locally Homeomorphic to Euclidean space? If so, why?
    – Anthony Peter
    Jul 16 '14 at 21:25






  • 3




    @AnthonyPeter: I'd recommend doing some reading about topological groups in general.
    – Kyle
    Jul 16 '14 at 21:27








13




13




It's part of the definition!
– Zhen Lin
Jul 16 '14 at 21:22




It's part of the definition!
– Zhen Lin
Jul 16 '14 at 21:22












You have a set. On that set, you have a group structure, and a differentiable structure. If the two structures play together nicely, it is a Lie group.
– Daniel Fischer
Jul 16 '14 at 21:23




You have a set. On that set, you have a group structure, and a differentiable structure. If the two structures play together nicely, it is a Lie group.
– Daniel Fischer
Jul 16 '14 at 21:23












This isn't a theorem, it's one of the Lie group axioms.
– Adam Hughes
Jul 16 '14 at 21:24




This isn't a theorem, it's one of the Lie group axioms.
– Adam Hughes
Jul 16 '14 at 21:24












@DanielFischer But is it Hausdorff and Locally Homeomorphic to Euclidean space? If so, why?
– Anthony Peter
Jul 16 '14 at 21:25




@DanielFischer But is it Hausdorff and Locally Homeomorphic to Euclidean space? If so, why?
– Anthony Peter
Jul 16 '14 at 21:25




3




3




@AnthonyPeter: I'd recommend doing some reading about topological groups in general.
– Kyle
Jul 16 '14 at 21:27




@AnthonyPeter: I'd recommend doing some reading about topological groups in general.
– Kyle
Jul 16 '14 at 21:27










2 Answers
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When you ask that $G times G to G$ is a smooth map, it means "with respect to the smooth structure you put on $G$ and the product differentiable structure on $G times G$", so that asking this map to be smooth makes sense since it becomes a map between smooth manifolds and you can ask yourself this question. So somewhere you already assumed there was a smooth structure on $G$ and this property you ask of multiplication is extra.



Hope that helps,






share|cite|improve this answer





























    1














    As you know that lie group is a structure where G×G→G, it that you can get any element in the same structure with other elements and an operation, now it is a manifold so it's chart is in a same structure which is a diffeomorphism of the elements, so the has to be smooth...






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      2 Answers
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      2 Answers
      2






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      active

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      3














      When you ask that $G times G to G$ is a smooth map, it means "with respect to the smooth structure you put on $G$ and the product differentiable structure on $G times G$", so that asking this map to be smooth makes sense since it becomes a map between smooth manifolds and you can ask yourself this question. So somewhere you already assumed there was a smooth structure on $G$ and this property you ask of multiplication is extra.



      Hope that helps,






      share|cite|improve this answer


























        3














        When you ask that $G times G to G$ is a smooth map, it means "with respect to the smooth structure you put on $G$ and the product differentiable structure on $G times G$", so that asking this map to be smooth makes sense since it becomes a map between smooth manifolds and you can ask yourself this question. So somewhere you already assumed there was a smooth structure on $G$ and this property you ask of multiplication is extra.



        Hope that helps,






        share|cite|improve this answer
























          3












          3








          3






          When you ask that $G times G to G$ is a smooth map, it means "with respect to the smooth structure you put on $G$ and the product differentiable structure on $G times G$", so that asking this map to be smooth makes sense since it becomes a map between smooth manifolds and you can ask yourself this question. So somewhere you already assumed there was a smooth structure on $G$ and this property you ask of multiplication is extra.



          Hope that helps,






          share|cite|improve this answer












          When you ask that $G times G to G$ is a smooth map, it means "with respect to the smooth structure you put on $G$ and the product differentiable structure on $G times G$", so that asking this map to be smooth makes sense since it becomes a map between smooth manifolds and you can ask yourself this question. So somewhere you already assumed there was a smooth structure on $G$ and this property you ask of multiplication is extra.



          Hope that helps,







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jul 16 '14 at 21:25









          Patrick Da Silva

          32k353106




          32k353106























              1














              As you know that lie group is a structure where G×G→G, it that you can get any element in the same structure with other elements and an operation, now it is a manifold so it's chart is in a same structure which is a diffeomorphism of the elements, so the has to be smooth...






              share|cite|improve this answer


























                1














                As you know that lie group is a structure where G×G→G, it that you can get any element in the same structure with other elements and an operation, now it is a manifold so it's chart is in a same structure which is a diffeomorphism of the elements, so the has to be smooth...






                share|cite|improve this answer
























                  1












                  1








                  1






                  As you know that lie group is a structure where G×G→G, it that you can get any element in the same structure with other elements and an operation, now it is a manifold so it's chart is in a same structure which is a diffeomorphism of the elements, so the has to be smooth...






                  share|cite|improve this answer












                  As you know that lie group is a structure where G×G→G, it that you can get any element in the same structure with other elements and an operation, now it is a manifold so it's chart is in a same structure which is a diffeomorphism of the elements, so the has to be smooth...







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Nov 23 at 12:32









                  explorer

                  2916




                  2916






























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