NO
(ignored inputs)COMMENT doi:10.1007/3-540-45744-5_49 [153] Example 20 submitted by: Raul Gutierrez and Salvador Lucas
Input:
   [ f(a,b,?x) -> f(?x,?x,?x),
     a -> c ]

Make it flat:
   [ f(a,b,?x) -> f(?x,?x,?x),
     a -> c ]
Time: 0.000 [s]

Make it Complete (R^):
   [ f(c,b,?x) = f(a,b,?x),
     f(c,b,?x) = f(?x,?x,?x),
     f(a,b,?x) = f(?x,?x,?x),
     a = c ]
Time: 0.000 [s]

CPNF:
   [ b … b,
     a … c ]
Time: 0.000 [s]

Now checking all the pairs in CW...

Time to check pairs: 0.000 [s]

The TRS doesn't have Uniqueness of Normal Forms.
Counter Example: 
     f(c,b,?x)
<->* f(?x,?x,?x)

proof:
     f(c,b,?x)
->R^ f(a,b,?x)
->R^ f(?x,?x,?x)

     f(?x,?x,?x)
Total Time: 0.001 [s]

problems/802.trs: Success(not UNC)
real 0.02
user 0.01
sys 0.01