A complex-analytic characterization of Lagrangian immersions in $\mathbb C^n$ with transverse double points

Fuente: arXiv
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Hauptverfasser: Gupta, Purvi, Sahu, Rudranil
Format: Preprint
Veröffentlicht: 2025
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author Gupta, Purvi
Sahu, Rudranil
author_facet Gupta, Purvi
Sahu, Rudranil
contents Given a compact smooth totally real immersed $n$-submanifold $M\subset\mathbb C^n$ with only finitely many transverse double points, it is known that if $M$ is Lagrangian with respect to some K{ä}hler form on $\mathbb C^n$, then it is rationally convex in $\mathbb C^n$ (Gayet, 2000), but the converse is not true (Mitrea, 2020). We show that $M$ is Lagrangian with respect to some K{ä}hler form on $\mathbb C^n$ if and only if $M$ is rationally convex {\em and} at each double point, the pair of transverse tangent planes to $M$ satisfies the following diagonalizability condition: there is a complex linear transformation on $\mathbb C^n$ that maps the pair to $\left(\mathbb R^n,(D+i)\mathbb R^n\right)$ for some real diagonal $n\times n$ matrix $D$.
format Preprint
id arxiv_https___arxiv_org_abs_2511_15306
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A complex-analytic characterization of Lagrangian immersions in $\mathbb C^n$ with transverse double points
Gupta, Purvi
Sahu, Rudranil
Complex Variables
Symplectic Geometry
32E20, 53D12
Given a compact smooth totally real immersed $n$-submanifold $M\subset\mathbb C^n$ with only finitely many transverse double points, it is known that if $M$ is Lagrangian with respect to some K{ä}hler form on $\mathbb C^n$, then it is rationally convex in $\mathbb C^n$ (Gayet, 2000), but the converse is not true (Mitrea, 2020). We show that $M$ is Lagrangian with respect to some K{ä}hler form on $\mathbb C^n$ if and only if $M$ is rationally convex {\em and} at each double point, the pair of transverse tangent planes to $M$ satisfies the following diagonalizability condition: there is a complex linear transformation on $\mathbb C^n$ that maps the pair to $\left(\mathbb R^n,(D+i)\mathbb R^n\right)$ for some real diagonal $n\times n$ matrix $D$.
title A complex-analytic characterization of Lagrangian immersions in $\mathbb C^n$ with transverse double points
topic Complex Variables
Symplectic Geometry
32E20, 53D12
url https://arxiv.org/abs/2511.15306