YES
(ignored inputs)COMMENT doi:10.1007/s00200-004-0148-6 [40] Example 1
Input:
   [ f(f(a)) -> f(f(f(a))),
     f(f(a)) -> f(a) ]

Make it flat:
   [ f(!cl_0) -> f(a),
     f(!cl_0) -> f(!cr_1),
     !cr_1 -> f(!cr_0),
     !cr_0 -> f(a),
     f(a) -> !cl_0 ]
Time: 0.000 [s]

Make it Complete (R^):
   [ f(!cr_0) = f(a),
     f(!cl_0) = !cl_0,
     f(!cl_0) = !cr_0,
     f(a) = !cr_1,
     f(!cr_1) = !cl_0,
     !cr_0 = !cr_1,
     !cl_0 = !cr_1,
     !cl_0 = f(!cr_0),
     !cr_0 = f(!cr_0),
     f(!cr_1) = !cr_0,
     f(a) = f(!cr_1),
     f(!cl_0) = f(a),
     f(!cr_0) = f(!cr_1),
     f(!cr_1) = !cr_1,
     f(!cl_0) = f(!cr_1),
     f(!cl_0) = f(!cr_0),
     f(!cl_0) = !cr_1,
     !cr_1 = f(!cr_0),
     !cr_0 = !cl_0,
     !cr_0 = f(a),
     f(a) = !cl_0 ]
Time: 0.003 [s]

CPNF:
   [ a … a,
     !cl_0 … !cl_0 ]
Time: 0.000 [s]

Now checking all the pairs in CW...

Time to check pairs: 0.000 [s]

The TRS has Uniqueness of Normal Forms.
Total Time: 0.004 [s]

problems/223.trs: Success(UNC)
real 0.02
user 0.02
sys 0.00