YES
Time: 0.017

Problem:
 Equations:
  
 TRS:
  fAC(fAC(i(x),i(y1)),y2) -> fAC(i(fAC(x,y1)),y2)
  fAC(one(),x) -> x
  phi(one(),x) -> x
  fAC(i(x),x) -> one()
  i(one()) -> one()
  i(i(x)) -> x
  phi(x,phi(y1,y2)) -> phi(fAC(x,y1),y2)
  fAC(i(fAC(x,y1)),y1) -> i(x)
  i(fAC(i(y1),x)) -> fAC(i(x),y1)
  fAC(i(x),i(y1)) -> i(fAC(x,y1))

Proof:
 AC-KBO Processor:
  precedence:
   fAC > phi ~ one ~ i
   weight function:
    w0 = 3
    w(one) = 13
    w(i) = 7
    w(phi) = 1
    w(fAC) = 0
   problem:
    Equations:
     
    TRS:
     
   Qed