Concept information
Preferred term
hairy ball theorem
Definition(s)
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The hairy ball theorem of algebraic topology (sometimes called the hedgehog theorem in Europe) states that there is no nonvanishing continuous tangent vector field on even-dimensional n-spheres. For the ordinary sphere, or 2‑sphere, if f is a continuous function that assigns a vector in R3 to every point p on a sphere such that f(p) is always tangent to the sphere at p, then there is at least one pole, a point where the field vanishes (a p such that f(p) = 0).
(Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/wiki/Hairy_ball_theorem)
Broader concept(s)
In other languages
URI
http://data.loterre.fr/ark:/67375/PSR-BS9SSM52-J
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