Diffeomorphism: surface x4 + y6 + z2 = 1

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Homework Help Overview

The discussion revolves around understanding the surface defined by the equation x4 + y6 + z2 = 1 and its potential diffeomorphism to a sphere. Participants are exploring the properties of this surface and the challenges in constructing a diffeomorphism.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants are attempting to establish a diffeomorphism by proposing mappings such as (x,y,z) → (x2, y3, z) and discussing the implications of these mappings, including issues of invertibility and smoothness. Questions arise regarding the necessity of a diffeomorphism versus a homeomorphism, as well as the nature of the surface's cross sections.

Discussion Status

The discussion is active with various approaches being explored. Some participants are questioning the need for a diffeomorphism, while others are considering alternative mappings and their properties. There is no explicit consensus, but productive ideas about graphing and radial mapping are being shared.

Contextual Notes

Participants are navigating constraints related to the smoothness of mappings and the characteristics of the surface, including its Euler characteristic. There is mention of specific points of concern, such as the behavior at x=0 and the nature of cross sections.

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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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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?
 


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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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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