MAYBE

Problem:
 ack(0(),y) -> s(y)
 ack(s(x),0()) -> ack(x,s(0()))
 ack(s(x),s(y)) -> ack(x,ack(s(x),y))

Proof:
 DP Processor:
  DPs:
   ack#(s(x),0()) -> ack#(x,s(0()))
   ack#(s(x),s(y)) -> ack#(s(x),y)
   ack#(s(x),s(y)) -> ack#(x,ack(s(x),y))
  TRS:
   ack(0(),y) -> s(y)
   ack(s(x),0()) -> ack(x,s(0()))
   ack(s(x),s(y)) -> ack(x,ack(s(x),y))
  EDG Processor:
   DPs:
    ack#(s(x),0()) -> ack#(x,s(0()))
    ack#(s(x),s(y)) -> ack#(s(x),y)
    ack#(s(x),s(y)) -> ack#(x,ack(s(x),y))
   TRS:
    ack(0(),y) -> s(y)
    ack(s(x),0()) -> ack(x,s(0()))
    ack(s(x),s(y)) -> ack(x,ack(s(x),y))
   graph:
    ack#(s(x),s(y)) -> ack#(s(x),y) ->
    ack#(s(x),0()) -> ack#(x,s(0()))
    ack#(s(x),s(y)) -> ack#(s(x),y) ->
    ack#(s(x),s(y)) -> ack#(s(x),y)
    ack#(s(x),s(y)) -> ack#(s(x),y) ->
    ack#(s(x),s(y)) -> ack#(x,ack(s(x),y))
    ack#(s(x),s(y)) -> ack#(x,ack(s(x),y)) ->
    ack#(s(x),s(y)) -> ack#(s(x),y)
    ack#(s(x),s(y)) -> ack#(x,ack(s(x),y)) ->
    ack#(s(x),s(y)) -> ack#(x,ack(s(x),y))
    ack#(s(x),0()) -> ack#(x,s(0())) ->
    ack#(s(x),s(y)) -> ack#(s(x),y)
    ack#(s(x),0()) -> ack#(x,s(0())) -> ack#(s(x),s(y)) -> ack#(x,ack(s(x),y))
   Restore Modifier:
    DPs:
     ack#(s(x),0()) -> ack#(x,s(0()))
     ack#(s(x),s(y)) -> ack#(s(x),y)
     ack#(s(x),s(y)) -> ack#(x,ack(s(x),y))
    TRS:
     ack(0(),y) -> s(y)
     ack(s(x),0()) -> ack(x,s(0()))
     ack(s(x),s(y)) -> ack(x,ack(s(x),y))
    SCC Processor:
     #sccs: 1
     #rules: 3
     #arcs: 7/9
     DPs:
      ack#(s(x),s(y)) -> ack#(s(x),y)
      ack#(s(x),s(y)) -> ack#(x,ack(s(x),y))
      ack#(s(x),0()) -> ack#(x,s(0()))
     TRS:
      ack(0(),y) -> s(y)
      ack(s(x),0()) -> ack(x,s(0()))
      ack(s(x),s(y)) -> ack(x,ack(s(x),y))
     Open