How Does a Function on Manifolds Change When Transferred from M to N?

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    Functions Manifolds
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Discussion Overview

The discussion revolves around the behavior of a real-valued function defined on a manifold M when transferred to another manifold N that is diffeomorphic to M. Participants explore the implications of diffeomorphism and the relationship between the function and the new manifold.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant inquires about the transformation of a function f defined on manifold M when transitioning to manifold N.
  • Another participant suggests that a map from M to N would act on the function f, implying a transformation process.
  • A question is raised regarding the meaning of diffeomorphic, particularly in the context of a manifold without a Riemann structure, suggesting that such a manifold could be very flexible.
  • There is a query about the nature of diffeomorphic manifolds, specifically whether a manifold M can be considered diffeomorphic to itself or if it can take on various forms like a ball or a cigar.
  • A later reply discusses the role of a diffeomorphism g from M to N and how the composition of g^-1 and f relates to the mapping from N to R.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the implications of diffeomorphism and the transformation of functions, indicating that multiple competing views remain on the topic.

Contextual Notes

There are limitations regarding the definitions of diffeomorphism and the assumptions about the geometric properties of manifolds, which remain unresolved in the discussion.

Icosahedron
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Assume you have two manifolds M and N diffeomorphic to another. Also, there is a real-valued function f defined on M.

What happens with f when you go from M to N? How is f related to N?

thanks
 
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If you have a map from M to N does the map not also act on the function f and transform it appropriately?
 
What actually does diffeomorphic really mean?

Take a manifold M without Riemann structure defined on, i.e. without any geometric properties, so that makes it very malleable.

Is not every manifold diffeomorphic to M already M?
 
If my manifold M can be a ball, a cigar or what have you, what then is a to M diffeomorphic manifold N?
 
What happens with f when you go from M to N? How is f related to N?

Consider the diffeomorphism g:M-->N.
Then you have that the composition of g^-1 and f, maps from N to R. Is that what you are looking for?
 

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