ISSN:
1572-9044
Keywords:
Hilbert space
;
commuting unitary operators
;
Riesz basis
;
wandering subspaces
;
multiresolution approximation
;
duality principle
;
box splines
;
41A15
;
42C15
;
47B37
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mathematics
Notes:
Abstract Let (U=U 1, ...,U d ) be an orderedd-tuple of distinct, pairwise commuting, unitary operators on a complex Hilbert space ℋ, and letX:={x 1, ...,x r } ⊂ ℋ such that $$U^{\mathbb{Z}^d } X: = \{ U_1^{n_1 } \ldots U_d^{n_d } x_j :(n_1 , \ldots ,n_d ) \in \mathbb{Z}^d ,j = 1, \ldots ,r\} $$ is a Riesz basis of the closed linear spanV 0 of $$U^{\mathbb{Z}^d } X$$ . Suppose there is unitary operatorD on ℋ such thatV 0 ⊂D V 0 =:V 1 andU n D=DU An for alln ∈ ℤ d , whereA is ad ×d matrix with integer entries and Δ := det(A) ≠ 0. Then there is a subset Λ inV 1, withr(Δ − 1) vectors, such that $$U^{\mathbb{Z}^d } (\Gamma )$$ is a Riesz basis ofW 0, the orthogonal complement ofV 0 inV 1. The resulting multiscale and decomposition relations can be expressed in a Fourier representation by one single equation, in terms of which the duality principle follows easily. These results are a consequence of an extension, to a set of commuting unitary operators, of Robertson's Theorems on wandering subspace for a single unitary operator [24]. Conditions are given in order that $$U^{\mathbb{Z}^d } (\Gamma )$$ is a Riesz basis ofW 0. They are used in the construction of a class of linear spline wavelets on a four-direction mesh.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02070823
Permalink
