%0 Journal Article
%T A note on focus-focus singularities
%A Nguyen Tien Zung
%J Mathematics
%D 2001
%I arXiv
%X We give a topological and geometrical description of focus-focus singularities of integrable Hamiltonian systems. In particular, we explain why the monodromy around these singularities is non-trivial, a result obtained before by J.J. Duistermaat and others for some concrete systems.
%U http://arxiv.org/abs/math/0110147v1