Differentiable structure on product of manifolds to yield inclusion maps as imbeddings












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I am working through Munkres' "Elementary Differential Topology" and trying to do every exercise, but this one question has me somewhat stuck. It is exercise c on page 11. The exercise is as follows:



"Let $M$ and $N$ have class $C^r$; let $M$ be non-bounded. Construct a $C^r$ differentiable structure on $Mtimes N$ such that the natural inclusions of $M$ and $N$ into $Mtimes N$ are imbeddings. Why do we require M to be non-bounded?"



My initial effort was to define the differentiable structure of $Mtimes N$, denoted $mathcal{D}_{Mtimes N}$, to be the crossings of the neighborhoods of $M$ and $N$ and then the concatenation of their homeomorphisms i.e. ${(Utimes V, (h,g)) | (U,h)in mathcal{D}_M, (V,g)in mathcal{D}_N}.$ This I believe gets you that the inclusion maps are imbeddings. But I do not understand where I need that M is non-bounded. Any help with this is greatly appreciated.










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0












$begingroup$


I am working through Munkres' "Elementary Differential Topology" and trying to do every exercise, but this one question has me somewhat stuck. It is exercise c on page 11. The exercise is as follows:



"Let $M$ and $N$ have class $C^r$; let $M$ be non-bounded. Construct a $C^r$ differentiable structure on $Mtimes N$ such that the natural inclusions of $M$ and $N$ into $Mtimes N$ are imbeddings. Why do we require M to be non-bounded?"



My initial effort was to define the differentiable structure of $Mtimes N$, denoted $mathcal{D}_{Mtimes N}$, to be the crossings of the neighborhoods of $M$ and $N$ and then the concatenation of their homeomorphisms i.e. ${(Utimes V, (h,g)) | (U,h)in mathcal{D}_M, (V,g)in mathcal{D}_N}.$ This I believe gets you that the inclusion maps are imbeddings. But I do not understand where I need that M is non-bounded. Any help with this is greatly appreciated.










share|cite|improve this question









$endgroup$












  • $begingroup$
    To avoid corners.
    $endgroup$
    – Lord Shark the Unknown
    Jan 10 at 21:14














0












0








0





$begingroup$


I am working through Munkres' "Elementary Differential Topology" and trying to do every exercise, but this one question has me somewhat stuck. It is exercise c on page 11. The exercise is as follows:



"Let $M$ and $N$ have class $C^r$; let $M$ be non-bounded. Construct a $C^r$ differentiable structure on $Mtimes N$ such that the natural inclusions of $M$ and $N$ into $Mtimes N$ are imbeddings. Why do we require M to be non-bounded?"



My initial effort was to define the differentiable structure of $Mtimes N$, denoted $mathcal{D}_{Mtimes N}$, to be the crossings of the neighborhoods of $M$ and $N$ and then the concatenation of their homeomorphisms i.e. ${(Utimes V, (h,g)) | (U,h)in mathcal{D}_M, (V,g)in mathcal{D}_N}.$ This I believe gets you that the inclusion maps are imbeddings. But I do not understand where I need that M is non-bounded. Any help with this is greatly appreciated.










share|cite|improve this question









$endgroup$




I am working through Munkres' "Elementary Differential Topology" and trying to do every exercise, but this one question has me somewhat stuck. It is exercise c on page 11. The exercise is as follows:



"Let $M$ and $N$ have class $C^r$; let $M$ be non-bounded. Construct a $C^r$ differentiable structure on $Mtimes N$ such that the natural inclusions of $M$ and $N$ into $Mtimes N$ are imbeddings. Why do we require M to be non-bounded?"



My initial effort was to define the differentiable structure of $Mtimes N$, denoted $mathcal{D}_{Mtimes N}$, to be the crossings of the neighborhoods of $M$ and $N$ and then the concatenation of their homeomorphisms i.e. ${(Utimes V, (h,g)) | (U,h)in mathcal{D}_M, (V,g)in mathcal{D}_N}.$ This I believe gets you that the inclusion maps are imbeddings. But I do not understand where I need that M is non-bounded. Any help with this is greatly appreciated.







differential-topology product-space






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asked Jan 10 at 20:58









mnewmanmnewman

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  • $begingroup$
    To avoid corners.
    $endgroup$
    – Lord Shark the Unknown
    Jan 10 at 21:14


















  • $begingroup$
    To avoid corners.
    $endgroup$
    – Lord Shark the Unknown
    Jan 10 at 21:14
















$begingroup$
To avoid corners.
$endgroup$
– Lord Shark the Unknown
Jan 10 at 21:14




$begingroup$
To avoid corners.
$endgroup$
– Lord Shark the Unknown
Jan 10 at 21:14










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