$L^2$ extension of holomorphic functions and log canonical places

Fuente: arXiv
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Main Authors: Kim, Dano, Wang, Xu
Format: Preprint
Published: 2025
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author Kim, Dano
Wang, Xu
author_facet Kim, Dano
Wang, Xu
contents In an influential $L^2$ extension theorem due to Demailly, the finiteness of an $L^2$ norm called the Ohsawa norm determines whether a given holomorphic function can be extended. This result has been further generalized by Zhou and Zhu to the case when the quasi-plurisubharmonic defining function of the subvariety has non-analytic singularities. We show that, however, there exist many instances of such defining functions for which only the zero function has finite Ohsawa norm, so that the $L^2$ extension statement is void in such cases, even when it has a unique log canonical place. Such a defining function occurs already among some of the simplest non-analytic singularities, namely toric ones.
format Preprint
id arxiv_https___arxiv_org_abs_2505_00801
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle $L^2$ extension of holomorphic functions and log canonical places
Kim, Dano
Wang, Xu
Complex Variables
Algebraic Geometry
In an influential $L^2$ extension theorem due to Demailly, the finiteness of an $L^2$ norm called the Ohsawa norm determines whether a given holomorphic function can be extended. This result has been further generalized by Zhou and Zhu to the case when the quasi-plurisubharmonic defining function of the subvariety has non-analytic singularities. We show that, however, there exist many instances of such defining functions for which only the zero function has finite Ohsawa norm, so that the $L^2$ extension statement is void in such cases, even when it has a unique log canonical place. Such a defining function occurs already among some of the simplest non-analytic singularities, namely toric ones.
title $L^2$ extension of holomorphic functions and log canonical places
topic Complex Variables
Algebraic Geometry
url https://arxiv.org/abs/2505.00801