  This is a note on Beauville's problem (solved by Greb, Lehn and Rollenske in
the non-algebraic case and by Hwang and Weiss in general) whether a lagrangian
torus on an irreducible holomorphic symplectic manifold is a fiber of a
lagrangian fibration. We provide a different, very short solution in the
non-algebraic case and make some observations suggesting a different approach
in the algebraic case.
