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โœฆ   LIBER   โœฆ

Singularities of p-energy minimizing maps

โœ Scribed by Robert Hardt; Fanghua Lin; Changyou Wang


Book ID
101243857
Publisher
John Wiley and Sons
Year
1997
Tongue
English
Weight
350 KB
Volume
50
Category
Article
ISSN
0010-3640

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โœฆ Synopsis


Suppose โ„ฆ is a Lipschitz domain in R n , n โ‰ฅ 2, g : โˆ‚โ„ฆ โ†’ S n-1 is a Lipschitz map of degree d, and, for each p โˆˆ [n -1, n), u p : โ„ฆ โ†’ S n-1 is a p-energy minimizing map with u p | โˆ‚โ„ฆ = g. Then, for d = 0, u p necessarily has singularities, and

Here we discuss the behavior of u p and its singularities as p โ†‘ n and prove the following: THEOREM A For all p sufficiently close to n, depending on โ„ฆ and g, the set sing u p of singularities (i.e., discontinuities) of u p contains precisely |d| points, all interior to โ„ฆ. Also, for each a โˆˆ sing u p , deg[u p | โˆ‚B r (a)] = (-1) sgn d for all sufficiently small positive r.

THEOREM B Any sequence of p's approaching n contains a subsequence p i so that the sets sing u p i converge to a set A of |d| points in โ„ฆ, and the maps u p i converge strongly in C 1,ฮฑ on compact subsets of โ„ฆ \ A for some positive ฮฑ < 1. The limit map u n belongs to C 1,ฮฑ (โ„ฆ \ A, S n-1 ) โˆฉ C 0,ฮฑ (โ„ฆ \ A) and is n-harmonic. THEOREM C For n โ‰ฅ 3, there are positive numbers N = N (โ„ฆ, g) and ฮด = ฮด(โ„ฆ, g) so that, for all p โˆˆ [n -1, n), any p-energy minimizer u p with u p | โˆ‚โ„ฆ = g has at most N singularities, and these are separated from each other and from โˆ‚โ„ฆ by a distance at least ฮด. (For n = 2 one must keep p bounded away from 1 [11, theorem D].) THEOREM D There is an asymptotic formula โ„ฆ |โˆ‡u p | p dx = |d| (n -1) p 2 ฯ‰ n np + W g (a p 1 , . . . , a p |d| ) + o(np) as p โ†‘ n ,


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