The complexity of approximating a trembling hand perfect equilibrium of   a multi-player game in strategic form
  We consider the task of computing an approximation of a trembling hand perfect equilibrium for an n-player game in strategic form, n >= 3. We show that this task is complete for the complexity class FIXP_a. In particular, the task is polynomial time equivalent to the task of computing an approximation of a Nash equilibrium in strategic form games with three (or more) players. 
Kousha Etessami, Kristoffer Arnsfelt Hansen, Peter Bro Miltersen, and   Troels Bjerre Sorensen
cs.GT cs.CC