MAYBE

Problem:
 fst(0(),Z) -> nil()
 fst(s(X),cons(Y,Z)) -> cons(Y,fst(X,Z))
 from(X) -> cons(X,from(s(X)))
 add(0(),X) -> X
 add(s(X),Y) -> s(add(X,Y))
 len(nil()) -> 0()
 len(cons(X,Z)) -> s(len(Z))

Proof:
 DP Processor:
  DPs:
   fst#(s(X),cons(Y,Z)) -> fst#(X,Z)
   from#(X) -> from#(s(X))
   add#(s(X),Y) -> add#(X,Y)
   len#(cons(X,Z)) -> len#(Z)
  TRS:
   fst(0(),Z) -> nil()
   fst(s(X),cons(Y,Z)) -> cons(Y,fst(X,Z))
   from(X) -> cons(X,from(s(X)))
   add(0(),X) -> X
   add(s(X),Y) -> s(add(X,Y))
   len(nil()) -> 0()
   len(cons(X,Z)) -> s(len(Z))
  Usable Rule Processor:
   DPs:
    fst#(s(X),cons(Y,Z)) -> fst#(X,Z)
    from#(X) -> from#(s(X))
    add#(s(X),Y) -> add#(X,Y)
    len#(cons(X,Z)) -> len#(Z)
   TRS:
    
   CDG Processor:
    DPs:
     fst#(s(X),cons(Y,Z)) -> fst#(X,Z)
     from#(X) -> from#(s(X))
     add#(s(X),Y) -> add#(X,Y)
     len#(cons(X,Z)) -> len#(Z)
    TRS:
     
    graph:
     from#(X) -> from#(s(X)) -> from#(X) -> from#(s(X))
    Restore Modifier:
     DPs:
      fst#(s(X),cons(Y,Z)) -> fst#(X,Z)
      from#(X) -> from#(s(X))
      add#(s(X),Y) -> add#(X,Y)
      len#(cons(X,Z)) -> len#(Z)
     TRS:
      fst(0(),Z) -> nil()
      fst(s(X),cons(Y,Z)) -> cons(Y,fst(X,Z))
      from(X) -> cons(X,from(s(X)))
      add(0(),X) -> X
      add(s(X),Y) -> s(add(X,Y))
      len(nil()) -> 0()
      len(cons(X,Z)) -> s(len(Z))
     SCC Processor:
      #sccs: 1
      #rules: 1
      #arcs: 1/16
      DPs:
       from#(X) -> from#(s(X))
      TRS:
       fst(0(),Z) -> nil()
       fst(s(X),cons(Y,Z)) -> cons(Y,fst(X,Z))
       from(X) -> cons(X,from(s(X)))
       add(0(),X) -> X
       add(s(X),Y) -> s(add(X,Y))
       len(nil()) -> 0()
       len(cons(X,Z)) -> s(len(Z))
      Open