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On semi-global invariants for focus-focus singularities

San Vu Ngoc
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Abstract

This article gives a classification, up to symplectic equivalence, of singular Lagrangian foliations given by a completely integrable system of a 4-dimensional symplectic manifold, in a full neighbourhood of a singular leaf of focus-focus (=nodal) type.

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San Vu Ngoc. 2002-08-30. On semi-global invariants for focus-focus singularities. https://arxiv.org/abs/math/0208245

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