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Noboru Ogawa

Publications and source records attributed to Noboru Ogawa.

4 recordsLinked to original sources

On the neighborhood of a torus leaf and dynamics of holomorphic foliations

Let $X$ be a complex surface and $Y$ be an elliptic curve embedded in $X$. Assume that there exists a non-singular holomorphic foliation $\mathcal{F}$ with $Y$ as a compact leaf, defined on a neighborhood of $Y$ in $X$. We investigate the relation between Ueda's classification of the complex analytic structure of a neighborhood of $Y$ and complex dynamics of the holonomy of $\mathcal{F}$ along $Y$. More precisely, we show that the pair $(Y,X)$ is of type ($\gamma$) in his classification when there exists a closed curve in $Y$ along which the holonomy of $\mathcal{F}$ is irrationally indifferent and non-linearizable. We also investigate the metric semi-positivity of the line bundle determined by the divisor $Y$. Our approach is based on the theory of hedgehogs, due to P\'{e}rez-Marco.

math.CV

Local criteria for non embeddability of Levi-flat manifolds

We give local criteria for smooth non-embeddablity of Levi-flat manifolds. For this purpose, we pose an analogue of Ueda theory on the neighborhood structure of hypersurfaces in complex manifolds with topologically trivial normal bundles.

math.CV

The totally nonnegative part of the finite Toda lattice via a reducible rational curve

A totally nonnegative matrix is a real-valued matrix whose minors are all nonnegative. In this paper, we concern with the totally nonnegative structure of the finite Toda lattice, a classical integrable system, which is expressed as a differential equation of square matrices. The Toda flow naturally translates into a (multiplicative) linear flow on the (generalized) Jacobi variety associated with some reducible rational curve $X$. This correspondence provides an algebro-geometric characterization of the totally positive part of the Toda equation. We prove that the totally nonnegative part of the finite Toda lattice is isomorphic to a connected component of $\mathrm{Jac}(X)_{\mathbb{R}}$, the real part of the generalized Jacobi variety $\mathrm{Jac}(X)$, as semi-algebraic varieties.

math.DS