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Hedgehog


A hedgehog is an envelope parameterized by its Gauss map (Martinez-Maure 1996). Viewed another way, a hedgehog is a Minkowski difference of a convex body (Martinez-Maure 2003, 2004).

In two dimensions, the parametric equations for a hedgehog are

x=p(theta)costheta-p^'(theta)sintheta
(1)
y=p(theta)sintheta+p^'(theta)costheta
(2)

(correcting a sign error in Martinez-Maure 1996). A plane convex hedgehog has at least four polygon vertices where the curvature has a stationary value. A plane convex hedgehog of constant width has at least six vertices (Martinez-Maure 1996).

For definitions of a hedgehog in n dimensions, see Martinez-Maure (2001).


See also

Envelope, Hedgehog Metric

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References

Langevin, R.; Levitt, G.; and Rosenberg, H. "Hérissons et Multihérissons (Enveloppes paramétrées par leur application de Gauss." Warsaw: Singularities, 245-253, 1985. Banach Center Pub. 20, PWN Warsaw, 1988.Martinez-Maure, Y. "A Note on the Tennis Ball Theorem." Amer. Math. Monthly 103, 338-340, 1996.Martinez-Maure, Y. "Hedgehogs and Zonoids." Adv. Math. 158, 1-17, 2001.Martinez-Maure, Y. "Theorie des hérissons et polytopes." Comptes Rendus de l'Académie des Sciences de Paris, Sér. I 336, 241-244, 2003.Martinez-Maure, Y. "A Brunn-Minkowski Theory for Minimal Surfaces." Ill. J. Math. 48, 589-607, 2004.

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Hedgehog

Cite this as:

Weisstein, Eric W. "Hedgehog." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Hedgehog.html

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