How to show a mapping is a diffeomorphism

In summary, the conversation discusses proper etiquette for asking textbook-style questions in online forums and offers tips for getting effective help. The main points include posting in the appropriate section, defining terms and showing effort in solving the problem, and refraining from editing posts after receiving replies.
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whattttt
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0
mapping
 
Last edited:
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  • #2
Hint: What is |f(x,y)|?
 
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Uh, that was a strange way to edit your post. Does it mean that you have solved the problem now?

A few tips for the next time: When you need help with textbook-style questions, you should usually put them in the "calculus and beyond" section of the homework forum. The exception is if the topic is too advanced, e.g. if it's a difficult problem from a course for graduate students of mathematics. The basics of topology and differential geometry is not too advanced in my opinion. Many of the homework helpers will be able to assist you with that. You are also expected to define your terms, and to show us your own attempt to solve the problem, up to the point where you got stuck. If you have no idea where to begin, then it's OK to say that, and we'll give you a hint about where to begin. Also, don't change your post after you have received replies to it. Minor changes are OK, if you acknowledge that by adding an explanatory text, like "I fixed a typo in this equation after X's reply below".
 

1. What is a diffeomorphism?

A diffeomorphism is a type of function between two different manifolds (or spaces) that is both smooth and invertible. In simpler terms, it is a function that maps one space onto another in a smooth and reversible way.

2. What are the requirements for a mapping to be considered a diffeomorphism?

For a mapping to be considered a diffeomorphism, it must satisfy two main requirements: it must be a smooth function, meaning it has continuous derivatives of all orders, and it must be invertible, meaning there exists an inverse function that maps the second space back to the first.

3. How can I show that a mapping is a diffeomorphism?

To show that a mapping is a diffeomorphism, you must first prove that it is a smooth function by demonstrating that it has continuous derivatives of all orders. Then, you must show that it is invertible by finding the inverse function and proving that it also has continuous derivatives of all orders. You can also use the inverse function theorem, which states that a differentiable function with a non-zero Jacobian (determinant of the derivative) at a point is invertible at that point.

4. Can a diffeomorphism exist between two spaces of different dimensions?

No, a diffeomorphism can only exist between spaces of the same dimension. This is because the inverse function must also have the same dimension as the original function, and if the two spaces have different dimensions, it is not possible for the inverse function to exist.

5. Are all diffeomorphisms bijective?

Yes, all diffeomorphisms are bijective, meaning they are both injective (one-to-one) and surjective (onto). This is because they are invertible, so every point in the second space has a corresponding point in the first space, and vice versa.

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