Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2405.08265

On the subadditivity of generalized Kodaira dimensions

Bojie He·Xiangyu Zhou
View original source ↗Read source document ↗Export metadata ↓

Abstract

The goals of this paper are of two aspects. Firstly, we introduce the notion of generalized numerical Kodaira dimension with multiplier ideal sheaf and establish the subadditivity inequalities in terms of this notion, which can be used to give an analytic proof of O. Fujino's result on the subadditivity of the log Kodaira dimensions. Secondly, motivated by Zhou-Zhu's subadditivity of generalized Kodaira dimensions, we adopt another definition of generalized Kodaira dimension with multiplier ideal sheaf and show they are equal by using Okounkov bodies. As one application, we show that the superadditivity part in Zhou-Zhu's setting also holds true. As another application, we give an alternative proof of Zhou-Zhu's subadditivity formula, in the case when the singular metric $h_L$ has analytic singularities, by using generalized Iitaka fibrations.

Explore related subjects

math.CVmath.AG

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Bojie He, Xiangyu Zhou. 2024-05-14. On the subadditivity of generalized Kodaira dimensions. https://arxiv.org/abs/2405.08265

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

A Product Principle for Harmonic Schwarz Lemmas: Boxes, Polydiscs, and Metric Geometry

We establish an exact product principle for the Euclidean operator norm of differentials of harmonic maps. For a bounded domain \(G\subset\R^m\) and \(p\in G\), let \(M_G(p)\) denote the supremum of \(\|dF_0\|\) over harmonic maps \(F:\D\to G\) with \(F(0)=p\). For bounded domains \(G_j\subset\R^{m_j}\), we prove \[ M_{G_1\times\cdots\times G_N}(p_1,\ldots,p_N)^2 =\sum_{j=1}^N M_{G_j}(p_j)^2. \] The theorem separates the geometry of the individual factors from the Euclidean geometry of the product: the factor extremal constants combine by a sum-of-squares law, while equality is governed by a single compatibility condition, namely a common maximizing direction for the component differentials. Neither convexity nor attainment of the factor suprema is required. Combining the product principle with the sharp interval and disk factor problems yields exact operator-norm estimates and all equality cases for harmonic maps into boxes and polydiscs. In both families, for every extremal map, the real differential at the origin has one-dimensional image. The same factor constants also define coordinatewise metrics for which the harmonic contraction estimate is sharp when the source disk is equipped with its Poincaré metric of curvature \(-1\). For boxes, the resulting metric is complete and equals twice the restriction of the Kobayashi-Royden metric of the product of vertical strips. For polydiscs, the harmonic product metric is pointwise maximal among contracting metrics of the form \(\max_j a_j(p)|v_j|\), with \(a_j(p)>0\). It is strictly smaller than twice the Kobayashi-Royden metric on every nonzero tangent vector, and its induced path metric is incomplete.

math.CV↗
arXiv2026

Convolution Regularization Preserves the $L^2$-Estimate Property for $(1,n)$-Forms

In this paper, we prove that the \(L^2\)-estimate property for \((1,n)\)-forms is preserved under the standard convolution regularization. As applications, we show that any singular Hermitian metric satisfying the optimal or multiple coarse \(L^2\)-estimate property for \((n,1)\) or \((1,n)\)-forms is Griffiths semi-positive. This resolves a question posed by Deng--Ning--Wang and a question by Inayama.

math.CV↗