Eversion
A curve on the unit sphere 
is an eversion if it has no corners or cusps (but it may be self-intersecting). Theseproperties are guaranteed by requiring that the curve's velocity never vanishes. A mapping 
forms animmersion of the Circle into the Sphere Iff, for all 
,
Smale (1958) showed it is possible to turn a Sphere inside out (Sphere Eversion) using eversion.See also Sphere Eversion
References
Smale, S. ``A Classification of Immersions of the Two-Sphere.'' Trans. Amer. Math. Soc. 90, 281-290, 1958.
- Nonaveraging Sequence
- Noncentral Distribution
- Noncommutative Group
- Nonconformal Mapping
- Nonconstructive Proof
- Noncototient
- Noncylindrical Ruled Surface
- Nondecreasing Function
- Nondividing Set
- Nonessential Singularity
- Non-Euclidean Geometry
- Nonillion
- Nonincreasing Function
- Nonlinear Least Squares Fitting
- Nonnegative
- Nonnegative Integer
- Nonnegative Partial Sum
- Nonorientable Surface
- Nonpositive
- Nonsquarefree
- Nonstandard Analysis
- Nontotient
- Nonwandering
- Nonzero
- Nordstrand's Weird Surface