YES
Time: 0.009

Problem:
 Equations:
  fAC(fAC(x1,x2),x3) -> fAC(x1,fAC(x2,x3))
  fAC(x1,x2) -> fAC(x2,x1)
  fAC(x1,fAC(x2,x3)) -> fAC(fAC(x1,x2),x3)
  fAC(x2,x1) -> fAC(x1,x2)
 TRS:
  fAC(x,one()) -> x
  fAC(i(x),x) -> one()

Proof:
 AC-KBO Processor:
  precedence:
   fAC > i ~ one
   weight function:
    [i](x0) = x0 + 6,
    
    [one] = 8,
    
    [fAC](x0, x1) = x0 + x1 + 2
   problem:
    Equations:
     fAC(fAC(x1,x2),x3) -> fAC(x1,fAC(x2,x3))
     fAC(x1,x2) -> fAC(x2,x1)
     fAC(x1,fAC(x2,x3)) -> fAC(fAC(x1,x2),x3)
     fAC(x2,x1) -> fAC(x1,x2)
    TRS:
     
   Qed