Solution

ID: past-exam-of-the-classical-mechanics-course-of-part-b-of-the-physics-course-of-the-university-of-oxford/2016/4/d/solution

An autonomous Hamiltonian system with degrees of freedom is Liouville integrable if it has conserved functions , including the Hamiltonian, whose differentials are independent on a regular open set and which are in involution:
The equations can then be reduced locally to quadratures. The statement about action-angle coordinates on invariant tori additionally requires compact connected regular common level sets; integrable unbounded motion need not be periodic or lie on a torus.

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