40 citations · 64 across the 23 of their papers we have counts for
4 papers · 1 filter
On the Operators with Numerical Range in an Ellipse
Jim Agler, Zinaida A. Lykova, N. J. Young
We give new necessary and sufficient conditions for the numerical range of an operator to be a subset of the closed elliptical set $K_δ\subs…
A Hilbert space approach to singularities of functions
Jim Agler, Zinaida Lykova, N. J. Young
We introduce the notion of a pseudomultiplier of a Hilbert space of functions on a set . Roughly, a pseudomultiplier of is a function which multiplies…
Exterior products of operators and superoptimal analytic approximation
Dimitrios Chiotis, Zinaida Lykova, Nicholas Young
We give a new algorithm for the construction of the unique superoptimal analytic approximant of a given continuous matrix-valued function on the unit circle, making use of exterior…
Projectivity of Banach and -algebras of continuous fields
David Cushing, Zinaida A. Lykova
We give necessary and sufficient conditions for the left projectivity and biprojectivity of Banach algebras defined by locally trivial continuous fields of Banach algebras. We iden…