The rotation number for non-autonomous linear Hamiltonian systems I:
basic properties

with Roberta Fabbri and  Russell Johnson,
Z. Angew. Math. Phys. 54 (2003), 484-502.

The paper concerns the rotation number for a random family of linear non-autonomous
Hamiltonian systems. Several definitions corresponding to its analytic and geometrical
approaches are presented, and some of its main properties are studied, as its continuity
and its relation with the presence of exponential dichotomy