Hans Koch
On the Renormalization of Hamiltonian Flows, and Critical Invariant Tori
(54K, plain TeX)

ABSTRACT.  We analyze a renormalization group transformation R for 
partially analytic Hamiltonians, with emphasis on what seems to be 
needed for the construction of non-integrable fixed points. Under 
certain assumptions, which are supported by numerical data in the 
golden mean case, we prove that such a fixed point has a critical 
invariant torus. The proof is constructive and can be used for 
numerical computations. We also relate R to a renormalization group 
transformation for commuting maps.