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Jihun Yum

Publications and source records attributed to Jihun Yum.

9 recordsLinked to original sources

Statistical Bergman geometry

This paper explores the Bergman geometry of bounded domains $Ω$ in $\mathbb{C}^n$ through the lens of information geometry by introducing a mapping $Φ: Ω\rightarrow \mathcal{P}(Ω)$, where $\mathcal{P}(Ω)$ denotes a space of probability measures on $Ω$. A result by J. Burbea and C. Rao establishes that the pullback of the Fisher information metric, the fundamental Riemannian pseudo-metric in information geometry, via $Φ$ coincides with the Bergman metric of $Ω$. Building on this idea, we consider $Ω$ as a statistical model and present several interesting results within this framework. First, we derive a new statistical curvature formula for the Bergman metric by expressing it in terms of covariance. Second, given a proper holomorphic map $f: Ω_1 \rightarrow Ω_2$, we prove that if the induced measure push-forward $κ: \mathcal{P}(Ω_1) \rightarrow \mathcal{P}(Ω_2)$ preserves the Fisher information metrics, then $f$ must be a biholomorphism. Finally, we establish the consistency and the central limit theorem of the Fréchet sample mean for Calabi's diastasis function.

math.CV

Bergman local isometries are biholomorphisms

We prove that a proper holomorphic local isometry between bounded domains with respect to the Bergman metrics is necessarily a biholomorphism. The proof relies on a new method grounded in Information Geometry theories.

math.CV

Limit of Bergman kernels on a tower of coverings of compact Kähler manifolds

We prove the convergence of the Bergman kernels and the $L^2$-Hodge numbers on a tower of Galois coverings $\{X_j\}$ of a compact Kähler manifold $X$ converging to an infinite Galois (not necessarily universal) covering $\widetilde{X}$. We also show that, as an application, sections of canonical line bundle $K_{X_j}$ for sufficiently large $j$ give rise to an immersion into some projective space, if so do sections of $K_{\widetilde{X}}$.

math.CV

Diederich-Fornaess and Steinness indices for abstract CR manifolds

We propose the concept of Diederich--Fornæss and Steinness indices on compact pseudoconvex CR manifolds of hypersurface type in terms of the D'Angelo 1-form. When the CR manifold bounds a domain in a complex manifold, under certain additional non-degeneracy condition, those indices are shown to coincide with the original Diederich--Fornæss and Steinness indices of the domain, and CR invariance of the original indices follows.

math.CV

CR-invariance of the Steinness index

We characterize the Diederich-Fornaess index and the Steinness index in terms of a special 1-form, which we call D'Angelo 1-form. We then prove that the Diederich-Fornaess and Steinness indices are invariant under CR-diffeomorphisms by showing CR-invariance of D'Angelo 1-forms.

math.CV

On the Steinness index

We introduce the concept of Steinness index related to the Stein neighborhood basis. We then show several results: (1) The existence of Steinness index is equivalent to that of strong Stein neighborhood basis. (2) On the Diederich-Fornæss worm domains in particular, we present an explicit formula relating the Steinness index to the well-known Diederich-Fornæss index. (3) The Steinness index is 1 if a smoothly bounded pseudoconvex domain admits finitely many boundary points of infinite type.

math.CV

Invariance of Diederich-Fornaess index

We show that the Diederich-Fornaess index of a domain in a Stein manifold is invariant under CR-diffeomorphisms. For this purpose we also improve CR-extension theorem.

math.CV