-Isometries in Euclidean spaces
β Scribed by Igor A. Vestfrid
- Publisher
- Elsevier Science
- Year
- 2005
- Tongue
- English
- Weight
- 128 KB
- Volume
- 63
- Category
- Article
- ISSN
- 0362-546X
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β¦ Synopsis
Let 0 < r R and A be a subset of the n-dimensional Euclidean space E n , which is contained in B(x 0 , R) and contains points x 0 , x 0 + re 1 , . . . , x 0 + re n , where the vectors {e i } n i=1 are orthonormal. We show that if f : A β E n is an -isometry, then there is an affine isometry U such that f (x)-U(x)
(n) R/r for all x in A, where (n) = Cn. Moreover, if A is star-shaped with respect to x 0 and contains B(x 0 , r), then (n) = C log(n + 1). Both results are sharp.
π SIMILAR VOLUMES
We extend Maurey's theorem on the existence of a fixed point for an isometry of a nonempty closed bounded convex subset of a superreflexive space to obtain the existence of common fixed points for countable families of commuting isometries.
Even lattices similar to their duals are discussed in connection with modular forms for Fricke groups. In particular, lattices of level 2 with large Hermite number are considered, and an analogy between the seven levels \(l\) such that \(1+l\) divides 24 is stressed. "t 1995 Academic Press, Inc.