10 papers
Idempotent linear relations
Maria Laura Arias, Maximiliano Contino, Alejandra Maestripieri +1
A linear relation acting on a Hilbert space is idempotent if A triplet of subspaces is needed to characterize a given idempotent: $(\mathrm{ran} \, E, \mathrm{ran}(I-E…
A matrix formula for Schur complements of nonnegative selfadjoint linear relations
Maximiliano Contino, Alejandra Maestripieri, Stefania Marcantognini
If a nonnegative selfadjoint linear relation in a Hilbert space and a closed subspace are assumed to satisfy that the domain of is invariant under the orthogo…
Total least squares problems on infinite dimensional spaces
Maximiliano Contino, Guillermina Fongi, Alejandra Maestripieri +1
In this work we study weighted total least squares problems on infinite dimensional spaces. We show that in most cases this problem does not admit a solution (except in the trivial…
Products of positive operators
Maximiliano Contino, Michael A. Dritschel, Alejandra Maestripieri +1
On finite dimensional spaces, it is apparent that an operator is the product of two positive operators if and only if it is similar to a positive operator. Here, the class ${\mathc…
Semiclosed projections and applications
Maximiliano Contino, Alejandra Maestripieri, Stefania Marcantognini
We characterize the semiclosed projections and apply them to compute the Schur complement of a selfadjoint operator with respect to a closed subspace. These projections occur natur…
Global solutions of approximation problems in Hilbert spaces
Maximiliano Contino, Maria Eugenia Di Iorio y Lucero, Guillermina Fongi
We study three well-known minimization problems in Hilbert spaces: the weighted least squares problem and the related problems of abstract splines and smoothing. In each case we an…