Diffeomorphism: surface x4 + y6 + z2 = 1

In summary, the conversation discusses the surface x4 + y6 + z2 = 1 and the attempt to find a diffeomorphism to the sphere. The individual is having trouble constructing the diffeomorphism and asks for suggestions. They mention trying different mappings and possible applications, such as finding the Euler characteristic. In the end, they discuss the shape of the surface and suggest mapping radially from the origin would likely work.
  • #1
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I'm trying to figure out what the surface x4 + y6 + z2 = 1 looks like.
I want to say that it is diffeomorphic to the sphere because (x2)2 + (y3)2 + (z)2 = 1
but i can't seems to actually construct the diffeomorphism (I am having problems with the x2 being invertible).
Please let me know if I'm on the right track (if I'm even right)
 
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  • #2


I tried (x,y,z)|-->(x2,y3,z) but then only positive x are mapped to (and twice)
So then I tried (x,y,z)|-->(sgn(x)x2,y3,z) which is bijective but isn't smooth (it doesn't have a second derivative when x=0)
Any suggestions?
 
  • #3


You could just graph it. What are its cross sections in planes parallel to the x-y plane?

Or, you could just use your mapping to understand the points away from the points where where x=0, and find some other means of understanding the subspace of points of small x.

What is the application? Is it really not enough to simply have a homoeomorphism?

P.S. my instinct is to map radially from the origin. Descartes rule of signs proves this is well defined for all points not lying in a coordinate plane.,,,
 
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  • #4


I was hoping to find the euler characteristic for it, so i suppose a homeomorphism would be sufficient. In this case my second construction would be suitable correct?
I graphed the level curves and they are rounded off squares which is much like i anticipated. (also it suggests your idea of mapping out radially would probably work)
 
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1. What is a diffeomorphism?

A diffeomorphism is a smooth and invertible mapping between two differentiable manifolds. In simpler terms, it is a transformation that preserves the smoothness of a surface and allows for a one-to-one correspondence between points on two surfaces.

2. How is a diffeomorphism different from a homeomorphism?

A diffeomorphism is a type of homeomorphism, which is a continuous and bijective mapping between two topological spaces. However, a diffeomorphism also requires that the inverse mapping is differentiable, meaning that it preserves the smoothness of the surfaces being mapped.

3. What is the significance of the surface x4 + y6 + z2 = 1 in diffeomorphism?

This surface is known as a quadric surface, and it is often used as an example in diffeomorphism because it has interesting geometric properties. It is a smooth surface that can be transformed into other quadric surfaces using diffeomorphisms, making it a useful tool for understanding the concept.

4. How is diffeomorphism used in mathematics and science?

Diffeomorphism is used in a variety of fields, including differential geometry, topology, and physics. It allows for the transformation of complex surfaces and spaces, making it useful for visualizing and solving problems in these areas.

5. Are there any practical applications of diffeomorphism?

Yes, diffeomorphism has many practical applications, particularly in computer graphics and animation. It is also used in medical imaging to map and analyze complex biological structures, such as the brain. Additionally, it has applications in optimization and control theory for solving engineering and economic problems.

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