2013/05/28 by Gustavo Corach, Corach, Gustavo, Guillermina Fongi +3
Mathematics · #47A07 #47A58 #Advanced Banach Space Theory #Approximation Theory and Sequence Spaces #FOS: Mathematics #Functional Analysis (math.FA) #Mathematical Analysis and Transform Methods #Operator Algebras (math.OA) #math.FA #math.OA #msc:47A07 #msc:47A58
paper · pdf · doi:10.48550/arxiv.1305.6357
arxiv created 2013/05/28 · openalex publication_date 2013/05/28 · arxiv updated 2013/05/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
In this paper we study A-projections, i.e. operators of a Hilbert space \HH which act as projections when a seminorm is considered in \HH. A-projections were introduced by Mitra and Rao \cite[MitRao74] for finite dimensional spaces. We relate this concept to the theory of compatibility between positive operators and closed subspaces of \HH. We also study the relationship between weighted least squares problems and compatibility.