Codimension 1 Minimal Projections Onto The Lines In LP
Formulas for minimal projections, Minimal projection, Uniqueness of minimal projections
Journal of Approximation Theory
Let X denote a real Banach space and V a subspace of X; we say that projection Pmin:X→V is minimal if ‖Pmin‖≤‖P‖ for every projection P from X to V. Considered as a subspace of Lebesgue space Lp[−1,1] (p≥1), let Y≔[1,t] denote the subspace of lines. In this paper we consider several natural codimension 1 overspaces X⊃Y (within Lp) and characterize minimal projections Pmin:X→Y for p=2n. The characterization utilizes the (so called) Chalmers–Metcalf operator and as such makes heavy use of extremal pairs associated with projections. We include results that show minimal projections in this setting are unique and include a section where algorithms and numerical results for ‖Pmin‖ are given.
Department of Mathematics
Original Publication Date
DOI of published version
Lewicki, Grzegorz; Prophet, Michael; and Wah, "Codimension 1 Minimal Projections Onto The Lines In LP" (2022). Faculty Publications. 5287.