NO
Rewrite Rules:
   [ zero(0) -> true,
     zero(s(?x)) -> false,
     if(true,?y,?z) -> ?y,
     if(false,?y,?z) -> ?z,
     f(0) -> 0,
     f(?x) -> if(zero(?x),s(0),0) ]
Apply Direct Methods...
Inner CPs:
   [  ]
Outer CPs:
   [ 0 = if(zero(0),s(0),0) ]
Overlay, check Innermost Termination...
Innermost Terminating (hence Terminating), not WCR
Knuth & Bendix
Direct Methods: not CR

Final result: not CR
new/gncr.trs: Success(not CR)
(0 msec.)