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local Nagano theorem (Theorem)
Theorem 1 (Local Nagano Theorem)   Let $ \Omega \subset {\mathbb{R}}^n$ be an open neighbourhood of a point $ x^0$. Further let $ \mathfrak{g}$ be a Lie subalgebra of the Lie algebra of real analytic real vector fields on $ \Omega$ which is also a $ C^\omega(\Omega;{\mathbb{R}})$-module. Then there exists a real analytic submanifold $ M \subset \Omega$ with $ x^0 \in M$, such that for all $ x \in M$ we have
$\displaystyle T_x(M) = \mathfrak{g}(x) .$    

Furthermore the germ of $ M$ at $ x$ is the unique germ of a submanifold with this property.

Here note that $ T_x(M)$ is the tangent space of $ M$ at $ x$, $ C^\omega(\Omega;{\mathbb{R}})$ are the real analytic real valued functions on $ \Omega$. Also real analytic real vector fields on $ \Omega$ are the real analytic sections of $ T(\Omega)$, the real tangent bundle of $ \Omega$.

Definition 1   The germ of the manifold $ M$ is called the local Nagano leaf of $ \mathfrak{g}$ at $ x_0$.
Definition 2   The union of all connected real analytic embedded submanifolds of $ \Omega$ whose germ at $ x_0$ coincides with the germ of $ M$ at $ x_0$ is called the global Nagano leaf.

The global Nagano leaf turns out to be a connected immersed real analytic submanifold which may however not be an embedded submanifold of $ \Omega$.

Bibliography

1
M. Salah Baouendi, Peter Ebenfelt, Linda Preiss Rothschild. Real Submanifolds in Complex Space and Their Mappings, Princeton University Press, Princeton, New Jersey, 1999.



"local Nagano theorem" is owned by jirka.
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Other names:  Nagano's theorem
Also defines:  local Nagano leaf, Nagano leaf, global Nagano leaf
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Cross-references: embedded submanifolds, connected, union, manifold, tangent bundle, sections, functions, tangent space, property, germ of a submanifold, germ, real analytic submanifold, vector fields, real, real analytic, Lie algebra, subalgebra, point, neighbourhood, open

This is version 3 of local Nagano theorem, born on 2004-11-10, modified 2005-03-07.
Object id is 6464, canonical name is LocalNaganoTheorem.
Accessed 3358 times total.

Classification:
AMS MSC53B25 (Differential geometry :: Local differential geometry :: Local submanifolds)
 17B99 (Nonassociative rings and algebras :: Lie algebras and Lie superalgebras :: Miscellaneous)

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