The web of Resonances: the background represents the web of resonances of the quasi-integrable Hamiltonian:

, where  are action variables, are their conjugated

angles, and  is small. The set of lines in the picture represents the projection of the resonances of

the system on the plane of the actions , while the uniform background color represent the set of invariant

tori. The numerical method to obtain such a kind of pictures is described in the paper by Froeschle' C., Guzzo M. and

Lega E. :``Graphical Evolution of the Arnold Web: From Order to Chaos'' published in Science, Volume 289, n. 5487, 2000.