activity
20212025
most citedA polynomial approximation result for free Herglotz-Agler functions

2 citations · 3 across the 6 of their papers we have counts for

collaborators

7 papers

math.CV2025

Indefinite structure of the Bergman kernel on the open unit disk

Kenta Kojin, Shuhei Kuwahara, Michio Seto

In this paper, we focus on an indefinite structure lying behind the Bergman kernel on the open unit disk. In particular, an invariant distance, birational maps and an indefinite ke…

math.FA2025

Isometric Gelfand transforms of complete Nevanlinna-Pick spaces

Kenta Kojin

We show that any complete Nevanlinna-Pick space whose multiplier algebra has isometric Gelfand transform (or commutative C*-envelope) is essentially the Hardy space on the open uni…

math.FA2024

An RKHS approach to the indefinite Schwarz-Pick inequality on the bidisk

Kenta Kojin

In this short note, we will give a generalization of the indefinite Schwarz-Pick inequality due to Seto [8]. Our approach is based on a connection between complex geometry and the…

math.FA2024

Complex structure that admits complete Nevanlinna-Pick spaces of Hardy type

Kenta Kojin

In this paper, we will characterize those sets, over which every irreducible complete Nevanlinna--Pick space enjoys that its multiplier and supremum norms coincide. Moreover, we wi…

math.FA2023★ 1 cited

Some relations between Schwarz-Pick inequality and von Neumann's inequality

Kenta Kojin

We study a Schwarz-Pick type inequality for the Schur-Agler class . In our operator theoretical approach, von Neumann's inequality for a class of generic tuples of $2\time…

math.FA2022★ 2 cited

A polynomial approximation result for free Herglotz-Agler functions

Kenta Kojin

In this paper, we prove a noncommutative (nc for short) analog of Schwarz lemma for the nc Schur-Agler class and prove that the regular nc Schur-Agler class and the regular free He…

math.FA2021

A refined nc Oka-Weil theorem

Kenta Kojin

This short note refines nc Oka-Weil theorem by using a characterization of free compact nc sets based on the notion of dilation hulls. A consequence of it is that any free holomorp…