Diffeomorphism: surface x4 + y6 + z2 = 1

Click For Summary
SUMMARY

The surface defined by the equation x4 + y6 + z2 = 1 is being analyzed for its diffeomorphic properties to the sphere defined by (x2)2 + (y3)2 + z2 = 1. The initial mapping attempts, (x,y,z) → (x2, y3, z) and (x,y,z) → (sgn(x)x2, y3, z), reveal issues with invertibility and smoothness, particularly at x=0. Suggestions include graphing the surface and analyzing cross sections in planes parallel to the x-y plane, as well as considering radial mappings from the origin for further insights.

PREREQUISITES
  • Differential topology concepts, specifically diffeomorphism
  • Understanding of smooth mappings and their properties
  • Familiarity with graphing multivariable functions
  • Knowledge of Euler characteristic in topology
NEXT STEPS
  • Explore the properties of diffeomorphisms in differential topology
  • Learn about constructing smooth mappings and their inverses
  • Investigate the Euler characteristic and its implications for surfaces
  • Graph and analyze level curves of multivariable functions for better visualization
USEFUL FOR

Mathematicians, particularly those specializing in topology and differential geometry, as well as students and researchers interested in the properties of complex surfaces and their mappings.

blerg
Messages
64
Reaction score
0
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)
 
Physics news on Phys.org


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.,,,
 
Last edited:


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)
 
Last edited:

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 25 ·
Replies
25
Views
5K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K