Complexity of several constraint satisfaction problems using the   heuristic, classical, algorithm, WalkSAT
  We determine the complexity of several constraint satisfaction problems using the heuristic algorithm, WalkSAT. At large sizes N, the complexity increases exponentially with N in all cases. Perhaps surprisingly, out of all the models studied, the hardest for WalkSAT is the one for which there is a polynomial time algorithm. 
Marco Guidetti, A. P. Young
quant-ph cond-mat.stat-mech cs.CC