On the Complexity of the Anisotropic Kepler Problem and the Planar Isosceles Three 
Body Problem
Hava T. Siegelmann and Jeremy Schiff
We show how to associate a computation to certain
 2 degree of freedom hamiltonian systems, and use this to discuss
 the level of complexity of certain problems in the dynamics of
 these systems. A type of Turing machine over the reals can
 be identified, embedded in these systems.
Publication information: This paper was submitted to Complex Systems.
We got an encouraging referee report (the referee identified himself as 
Cris Moore) 
and a conditional acceptance provided we dealt with the points the referee
raised. Unfortunately Hava left Bar-Ilan and we never got around to it.