Problem:
 +(0(),x) -> x
 +(-(x),x) -> 0()
 +(+(x,y),z) -> +(x,+(y,z))
 +(x,y) -> +(y,x)
 -(0()) -> 0()
 -(-(x)) -> x
 -(+(x,y)) -> +(-(x),-(y))

Proof:
 Church Rosser Transformation Processor (ac):
  f4_AC(0(),x) -> x
  f4_AC(-(x),x) -> 0()
  -(0()) -> 0()
  -(-(x)) -> x
  -(f4_AC(x,y)) -> f4_AC(-(x),-(y))
  AC critical peaks: joinable
  AC-KBO Processor:
   precedence:
    - > 0 > f4_AC
    weight function:
     w0 = 4
     w(f4_AC) = 5
     w(0) = 4
     w(-) = 0
    problem:
     
    Qed