(ignored inputs)COMMENT Exercise 6.5{a} of \cite{BN98}
Rewrite Rules:
   [ f(g(f(?x))) -> ?x,
     f(g(?x)) -> g(f(?x)) ]
Apply Direct Methods...
Inner CPs:
   [ f(g(g(f(?x_1)))) = g(?x_1),
     f(g(?x)) = g(f(?x)) ]
Outer CPs:
   [ ?x = g(f(f(?x))) ]
not Overlay, check Termination...
Terminating, not WCR
Knuth&Bendix
Direct Methods: not CR

Final result: not CR
/local-scratch/hzankl/2012/cops2012/10.trs: Success(not CR)
(4 msec.)