YES
Time: 0.067

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(g(g(x)),x) -> fAC(g(x),g(x))
  fAC(fAC(x,x),g(x)) -> fAC(x,h(x))

Proof:
 Matrix Interpretation Processor:
  dimension: 1
  interpretation:
   [h](x0) = x0,
   
   [g](x0) = 4x0 + 1,
   
   [fAC](x0, x1) = x0 + x1 + 2
  orientation:
   fAC(g(g(x)),x) = 17x + 7 >= 8x + 4 = fAC(g(x),g(x))
   
   fAC(fAC(x,x),g(x)) = 6x + 5 >= 2x + 2 = fAC(x,h(x))
  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