YES
Time: 0.044

Problem:
 Equations:
  
 TRS:
  pAC(x,zero()) -> x
  pAC(pAC(pAC(pAC(a(),a()),b()),b()),b()) -> pAC(pAC(pAC(a(),a()),a()),b())
  pAC(pAC(pAC(pAC(a(),a()),a()),a()),b()) -> pAC(pAC(pAC(a(),a()),b()),b())

Proof:
 AC-KBO Processor:
  precedence:
   zero > pAC > b > a
   weight function:
    w0 = 1
    w(a) = 8
    w(b) = 4
    w(zero) = 1
    w(pAC) = 0
   problem:
    Equations:
     
    TRS:
     
   Qed