Confusion about the definition of an n-differentiable manifold in Bredon's book “Topology and Geometry”












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In Definition 2.1 on page 68 and 69 Glen E. Bredon defines a $n$-differentiable manifold as a second countable Hausdorff space $M^n$ and a collection of charts such that:




  1. a chart is a homeomorphism $phi:Uto U'subsetmathbb{R}^n$ where $U$ is open in $M^n$ and $U'$ is open in $mathbb{R}^n$;


  2. each point $xin M$ is in the domain of some chart;


  3. for charts $phi:Uto U'subset mathbb{R}^n$ and $psi:Vto V'subsetmathbb{R}^n$ we have that the “change of coordinates” $phipsi^{-1}:psi(Ucap V)tophi(Ucap V)$ is $C^infty$; and

  4. the collection of charts is maximal with properties 1, 2, and 3.


I'm confused about property 2 where he talks about a point $xin M$ being element of an open subset of $M^n$.



In definition 2.4 on the next two pages he talks about an functionally structured Hausdorff space $(F,M^n)$ where he also talks about points $xin M$ being elements of open subsets of $M^n$.



My guess is that he writes $M^n$ to imply that he talks about an $n$-differentiable manifold or is he talking about an embedding of $M$ in $M^n$?










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    The notation $M^n$ is usually used to indicate that $M$ is of dimension $n$, indeed
    – Max
    Jun 12 at 9:57


















1














In Definition 2.1 on page 68 and 69 Glen E. Bredon defines a $n$-differentiable manifold as a second countable Hausdorff space $M^n$ and a collection of charts such that:




  1. a chart is a homeomorphism $phi:Uto U'subsetmathbb{R}^n$ where $U$ is open in $M^n$ and $U'$ is open in $mathbb{R}^n$;


  2. each point $xin M$ is in the domain of some chart;


  3. for charts $phi:Uto U'subset mathbb{R}^n$ and $psi:Vto V'subsetmathbb{R}^n$ we have that the “change of coordinates” $phipsi^{-1}:psi(Ucap V)tophi(Ucap V)$ is $C^infty$; and

  4. the collection of charts is maximal with properties 1, 2, and 3.


I'm confused about property 2 where he talks about a point $xin M$ being element of an open subset of $M^n$.



In definition 2.4 on the next two pages he talks about an functionally structured Hausdorff space $(F,M^n)$ where he also talks about points $xin M$ being elements of open subsets of $M^n$.



My guess is that he writes $M^n$ to imply that he talks about an $n$-differentiable manifold or is he talking about an embedding of $M$ in $M^n$?










share|cite|improve this question


















  • 1




    The notation $M^n$ is usually used to indicate that $M$ is of dimension $n$, indeed
    – Max
    Jun 12 at 9:57
















1












1








1







In Definition 2.1 on page 68 and 69 Glen E. Bredon defines a $n$-differentiable manifold as a second countable Hausdorff space $M^n$ and a collection of charts such that:




  1. a chart is a homeomorphism $phi:Uto U'subsetmathbb{R}^n$ where $U$ is open in $M^n$ and $U'$ is open in $mathbb{R}^n$;


  2. each point $xin M$ is in the domain of some chart;


  3. for charts $phi:Uto U'subset mathbb{R}^n$ and $psi:Vto V'subsetmathbb{R}^n$ we have that the “change of coordinates” $phipsi^{-1}:psi(Ucap V)tophi(Ucap V)$ is $C^infty$; and

  4. the collection of charts is maximal with properties 1, 2, and 3.


I'm confused about property 2 where he talks about a point $xin M$ being element of an open subset of $M^n$.



In definition 2.4 on the next two pages he talks about an functionally structured Hausdorff space $(F,M^n)$ where he also talks about points $xin M$ being elements of open subsets of $M^n$.



My guess is that he writes $M^n$ to imply that he talks about an $n$-differentiable manifold or is he talking about an embedding of $M$ in $M^n$?










share|cite|improve this question













In Definition 2.1 on page 68 and 69 Glen E. Bredon defines a $n$-differentiable manifold as a second countable Hausdorff space $M^n$ and a collection of charts such that:




  1. a chart is a homeomorphism $phi:Uto U'subsetmathbb{R}^n$ where $U$ is open in $M^n$ and $U'$ is open in $mathbb{R}^n$;


  2. each point $xin M$ is in the domain of some chart;


  3. for charts $phi:Uto U'subset mathbb{R}^n$ and $psi:Vto V'subsetmathbb{R}^n$ we have that the “change of coordinates” $phipsi^{-1}:psi(Ucap V)tophi(Ucap V)$ is $C^infty$; and

  4. the collection of charts is maximal with properties 1, 2, and 3.


I'm confused about property 2 where he talks about a point $xin M$ being element of an open subset of $M^n$.



In definition 2.4 on the next two pages he talks about an functionally structured Hausdorff space $(F,M^n)$ where he also talks about points $xin M$ being elements of open subsets of $M^n$.



My guess is that he writes $M^n$ to imply that he talks about an $n$-differentiable manifold or is he talking about an embedding of $M$ in $M^n$?







differential-topology smooth-manifolds






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asked Jun 12 at 9:43









messias

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  • 1




    The notation $M^n$ is usually used to indicate that $M$ is of dimension $n$, indeed
    – Max
    Jun 12 at 9:57
















  • 1




    The notation $M^n$ is usually used to indicate that $M$ is of dimension $n$, indeed
    – Max
    Jun 12 at 9:57










1




1




The notation $M^n$ is usually used to indicate that $M$ is of dimension $n$, indeed
– Max
Jun 12 at 9:57






The notation $M^n$ is usually used to indicate that $M$ is of dimension $n$, indeed
– Max
Jun 12 at 9:57












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From the comment above by @Max.





You are right, the notation $M^n$ is used to indicate that $M$ is an $n$-dimensional differentiable manifold. It is not used in the sense of the Cartesian product $M times dots times M$.






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    From the comment above by @Max.





    You are right, the notation $M^n$ is used to indicate that $M$ is an $n$-dimensional differentiable manifold. It is not used in the sense of the Cartesian product $M times dots times M$.






    share|cite|improve this answer




























      0














      From the comment above by @Max.





      You are right, the notation $M^n$ is used to indicate that $M$ is an $n$-dimensional differentiable manifold. It is not used in the sense of the Cartesian product $M times dots times M$.






      share|cite|improve this answer


























        0












        0








        0






        From the comment above by @Max.





        You are right, the notation $M^n$ is used to indicate that $M$ is an $n$-dimensional differentiable manifold. It is not used in the sense of the Cartesian product $M times dots times M$.






        share|cite|improve this answer














        From the comment above by @Max.





        You are right, the notation $M^n$ is used to indicate that $M$ is an $n$-dimensional differentiable manifold. It is not used in the sense of the Cartesian product $M times dots times M$.







        share|cite|improve this answer














        share|cite|improve this answer



        share|cite|improve this answer








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