24 citations · 24 across the 13 of their papers we have counts for
7 papers · 1 filter
Metric functionals and weak convergence
Armando W. Gutiérrez, Olavi Nevanlinna
We introduce a notion of weak convergence in arbitrary metric spaces. Metric functionals are key in our analysis: weak convergence of sequences in a given metric space is tested ag…
Subinvariant metric functionals for nonexpansive mappings
Armando W. Gutiérrez, Olavi Nevanlinna
We investigate the existence of subinvariant metric functionals for commuting families of nonexpansive mappings in noncompact subsets of Banach spaces. Our findings underscore the…
Simplifying operators by polynomials
Olavi Nevanlinna
We collect and organise known results and add some new ones of the following nature: if A is a bounded operator in a Hilbert or Banach space, does there exist a nonconstant polynom…
An iteration scheme for monotone operators in Hilbert spaces
Olavi Nevanlinna
We give an iteration scheme for finding zeros of maximal monotone operators in Hilbert spaces. We assume that the operator is defined in the whole space. The iterates converge stro…
Sylvester equations and polynomial separation of spectra
Olavi Nevanlinna
Sylvester equations have unique solutions for all when the spectra of and are disjoint. Here and are bounded operators in Banach spaces. We discuss th…
A functional calculus and the complex conjugate of a matrix
Olavi Nevanlinna
Based on Stokes' theorem we derive a non-holomorphic functional calculus for matrices, assuming sufficient smoothness near eigenvalues, corresponding to the size of related Jordan…