YES
input TRS:
   [ a -> a,
     f(f(?x,b),?y) -> f(?y,b),
     f(b,?y) -> f(?y,b),
     f(?x,a) -> b ]
TRS:
   [ a -> a,
     f(f(?x,b),?y) -> f(?y,b),
     f(b,?y) -> f(?y,b),
     f(?x,a) -> b ]
confluent TRS:
   [ a -> a,
     f(f(?x,b),?y) -> f(?y,b),
     f(b,?y) -> f(?y,b),
     f(?x,a) -> b,
     f(a,b) -> b ]
UNC Completion (Strongly Closed)
problems/ex6.trs: Success(UNC)
(0 msec.)