12 papers · 1 filter
Factorizations of linear relations by idempotents
M. Laura Arias, Maximiliano Contino, Stefania Marcantognini
We study the class of those linear relations that can be factorized as products of idempotent relations. We provide several characterizations of this class, extending known factori…
A note on a Halmos problem
Maximiliano Contino, Eva Gallardo-Gutierrez
We address the existence of non-trivial closed invariant subspaces of operators on Banach spaces whenever their square have or, more generally, whether there exists a pol…
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…