YES
(ignored inputs)COMMENT Cops #647 - #721: generated ground TRSs; evenly distributed in the UNR/UNC/NFP/CR hierarchy submitted by: Bertram Felgenhauer
Rewrite Rules:
   [ c -> b,
     a -> a,
     b -> b,
     f(f(a)) -> c ]
Apply Direct Methods...
Inner CPs:
   [ f(f(a)) = c ]
Outer CPs:
   [  ]
Linear
(inner) Parallel CPs:
   [ f(f(a)) = c {} ]
Toyama (Parallel CPs)
Direct Methods: CR

Combined result: CR
693.trs: Success(CR)
(0 msec.)