Generalized Tanaka prolongation and convergence of formal equivalence between embeddings

Fuente: arXiv
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Autori principali: Hong, Jaehyun, Hwang, Jun-Muk
Natura: Preprint
Pubblicazione: 2024
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author Hong, Jaehyun
Hwang, Jun-Muk
author_facet Hong, Jaehyun
Hwang, Jun-Muk
contents The works of Commichau--Grauert and Hirschowitz showed that a formal equivalence between embeddings of a compact complex manifold is convergent, if the embeddings have sufficiently positive normal bundles in a suitable sense. We show that the convergence still holds under the weaker assumption of semi-positive normal bundles if some geometric conditions are satisfied. Our result can be applied to many examples of general minimal rational curves, including general lines on a smooth hypersurface of degree less than $n$ in the $(n+1)$-dimensional projective space. As a key ingredient of our arguments, we formulate and prove a generalized version of Tanaka's prolongation procedure for geometric structures subordinate to vector distributions, a result of independent interest. When applied to the universal family of the deformations of the compact submanifolds satisfying our geometric conditions, the generalized Tanaka prolongation gives a natural absolute parallelism on a suitable fiber space. A formal equivalence of embeddings must preserve these absolute parallelisms, which implies its convergence.
format Preprint
id arxiv_https___arxiv_org_abs_2408_15537
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Generalized Tanaka prolongation and convergence of formal equivalence between embeddings
Hong, Jaehyun
Hwang, Jun-Muk
Differential Geometry
Complex Variables
32K07, 58A30, 32C22
The works of Commichau--Grauert and Hirschowitz showed that a formal equivalence between embeddings of a compact complex manifold is convergent, if the embeddings have sufficiently positive normal bundles in a suitable sense. We show that the convergence still holds under the weaker assumption of semi-positive normal bundles if some geometric conditions are satisfied. Our result can be applied to many examples of general minimal rational curves, including general lines on a smooth hypersurface of degree less than $n$ in the $(n+1)$-dimensional projective space. As a key ingredient of our arguments, we formulate and prove a generalized version of Tanaka's prolongation procedure for geometric structures subordinate to vector distributions, a result of independent interest. When applied to the universal family of the deformations of the compact submanifolds satisfying our geometric conditions, the generalized Tanaka prolongation gives a natural absolute parallelism on a suitable fiber space. A formal equivalence of embeddings must preserve these absolute parallelisms, which implies its convergence.
title Generalized Tanaka prolongation and convergence of formal equivalence between embeddings
topic Differential Geometry
Complex Variables
32K07, 58A30, 32C22
url https://arxiv.org/abs/2408.15537