4 citations · 4 across the 6 of their papers we have counts for
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Dilation Theory for Scaled -Numerical Ranges
Matias Kaunisto, Ryan O'Loughlin, Jani Virtanen
We generalise Berger's dilation theorem from numerical ranges to scaled -numerical ranges. Specifically, we prove that if the scaled -numerical range is co…
The Complete Crouzeix Conjecture in Dimension Three and the Clouâtre-Ostermann-Ransford conjecture
Per Åhag, Rafał Czyż, Jani Virtanen
We settle the complete Crouzeix conjecture for matrices of order at most three and prove the Q-algebra case of the completely bounded Clouâtre--Ostermann--Ransford (COR) conjecture…
On the abstract approach to spectral constants: a proof of the Clouâtre--Ostermann--Ransford conjecture
Catalin Badea, Ryan O'Loughlin, Jani Virtanen
Clouâtre, Ostermann, and Ransford formulated an abstract version of Crouzeix's conjecture involving a bounded unital homomorphism from a uniform algebra into matrices and a unital…
A Counterexample to the Gau--Wang--Wu Conjecture on Partial Isometries
Ryan O'Loughlin, Jani Virtanen
We disprove the conjecture of Gau, Wang and Wu that the numerical range of a finite-dimensional partial isometry, when circular, must be centred at the origin. More precisely, we p…
Maximal Plurisubharmonic Functions and Fujii-Seo Determinants in Hilbert spaces
Per Åhag, Rafał Czyż, Antti Perälä +1
A maximal plurisubharmonic function on an infinite-dimensional Hilbert space can have an injective, noncompact Levi operator at every point. This raises the question of what replac…