REVERSED WAVELET FUNCTIONS AND SUBSPACES
Abstract
Let the operators D and T be the dilation-by-2 and translation-by-1 on , which are both bilateral shifts of infinite multiplicity. If ψ(·) in
is a wavelet, then {DmTnψ(·)}(m,n)∈ℤ2 is an orthonormal basis for the Hilbert space
but the reversed set {TnDmψ(·)}(n,m)∈ℤ2 is not. In this paper we investigate the role of the reversed functions TnDmψ(·) in wavelet theory. As a consequence, we exhibit an orthogonal decomposition of
into T-reducing subspaces upon which part of the bilateral shift T consists of a countably infinite direct sum of bilateral shifts of multiplicity one, which mirrors a well-known decomposition of the bilateral shift D.