We define and characterize a frame-like stable decomposition for subspaces in a separable Hilbert space. We call in pseudoframes for subspaces (PFFS). Properties of PFFS are discussed. A necessary and sufficient condition for the construction is provided. An analytical formula for the construction of PFFS is also derived. An example is studied both as a motivation of the theoretical study of such pseudoframes and as an actual construction. Potential applications of PFFS are discussed.
"Pseudoframes for subspaces with applications", Proc. SPIE 3458, Wavelet Applications in Signal and Imaging Processing VI, (19 October 1998); doi: 10.1117/12.328126; https://doi.org/10.1117/12.328126