MAYBE

Problem:
 a__2nd(cons(X,cons(Y,Z))) -> mark(Y)
 a__from(X) -> cons(mark(X),from(s(X)))
 mark(2nd(X)) -> a__2nd(mark(X))
 mark(from(X)) -> a__from(mark(X))
 mark(cons(X1,X2)) -> cons(mark(X1),X2)
 mark(s(X)) -> s(mark(X))
 a__2nd(X) -> 2nd(X)
 a__from(X) -> from(X)

Proof:
 DP Processor:
  DPs:
   a__2nd#(cons(X,cons(Y,Z))) -> mark#(Y)
   a__from#(X) -> mark#(X)
   mark#(2nd(X)) -> mark#(X)
   mark#(2nd(X)) -> a__2nd#(mark(X))
   mark#(from(X)) -> mark#(X)
   mark#(from(X)) -> a__from#(mark(X))
   mark#(cons(X1,X2)) -> mark#(X1)
   mark#(s(X)) -> mark#(X)
  TRS:
   a__2nd(cons(X,cons(Y,Z))) -> mark(Y)
   a__from(X) -> cons(mark(X),from(s(X)))
   mark(2nd(X)) -> a__2nd(mark(X))
   mark(from(X)) -> a__from(mark(X))
   mark(cons(X1,X2)) -> cons(mark(X1),X2)
   mark(s(X)) -> s(mark(X))
   a__2nd(X) -> 2nd(X)
   a__from(X) -> from(X)
  CDG Processor:
   DPs:
    a__2nd#(cons(X,cons(Y,Z))) -> mark#(Y)
    a__from#(X) -> mark#(X)
    mark#(2nd(X)) -> mark#(X)
    mark#(2nd(X)) -> a__2nd#(mark(X))
    mark#(from(X)) -> mark#(X)
    mark#(from(X)) -> a__from#(mark(X))
    mark#(cons(X1,X2)) -> mark#(X1)
    mark#(s(X)) -> mark#(X)
   TRS:
    a__2nd(cons(X,cons(Y,Z))) -> mark(Y)
    a__from(X) -> cons(mark(X),from(s(X)))
    mark(2nd(X)) -> a__2nd(mark(X))
    mark(from(X)) -> a__from(mark(X))
    mark(cons(X1,X2)) -> cons(mark(X1),X2)
    mark(s(X)) -> s(mark(X))
    a__2nd(X) -> 2nd(X)
    a__from(X) -> from(X)
   graph:
    a__from#(X) -> mark#(X) -> mark#(2nd(X)) -> mark#(X)
    a__from#(X) -> mark#(X) -> mark#(2nd(X)) -> a__2nd#(mark(X))
    a__from#(X) -> mark#(X) -> mark#(from(X)) -> mark#(X)
    a__from#(X) -> mark#(X) -> mark#(from(X)) -> a__from#(mark(X))
    a__from#(X) -> mark#(X) -> mark#(cons(X1,X2)) -> mark#(X1)
    a__from#(X) -> mark#(X) -> mark#(s(X)) -> mark#(X)
    mark#(2nd(X)) -> mark#(X) -> mark#(2nd(X)) -> mark#(X)
    mark#(2nd(X)) -> mark#(X) -> mark#(2nd(X)) -> a__2nd#(mark(X))
    mark#(2nd(X)) -> mark#(X) -> mark#(from(X)) -> mark#(X)
    mark#(2nd(X)) -> mark#(X) -> mark#(from(X)) -> a__from#(mark(X))
    mark#(2nd(X)) -> mark#(X) -> mark#(cons(X1,X2)) -> mark#(X1)
    mark#(2nd(X)) -> mark#(X) -> mark#(s(X)) -> mark#(X)
    mark#(2nd(X)) -> a__2nd#(mark(X)) ->
    a__2nd#(cons(X,cons(Y,Z))) -> mark#(Y)
    mark#(from(X)) -> a__from#(mark(X)) -> a__from#(X) -> mark#(X)
    mark#(from(X)) -> mark#(X) -> mark#(2nd(X)) -> mark#(X)
    mark#(from(X)) -> mark#(X) -> mark#(2nd(X)) -> a__2nd#(mark(X))
    mark#(from(X)) -> mark#(X) -> mark#(from(X)) -> mark#(X)
    mark#(from(X)) -> mark#(X) -> mark#(from(X)) -> a__from#(mark(X))
    mark#(from(X)) -> mark#(X) -> mark#(cons(X1,X2)) -> mark#(X1)
    mark#(from(X)) -> mark#(X) -> mark#(s(X)) -> mark#(X)
    mark#(s(X)) -> mark#(X) -> mark#(2nd(X)) -> mark#(X)
    mark#(s(X)) -> mark#(X) -> mark#(2nd(X)) -> a__2nd#(mark(X))
    mark#(s(X)) -> mark#(X) -> mark#(from(X)) -> mark#(X)
    mark#(s(X)) -> mark#(X) -> mark#(from(X)) -> a__from#(mark(X))
    mark#(s(X)) -> mark#(X) -> mark#(cons(X1,X2)) -> mark#(X1)
    mark#(s(X)) -> mark#(X) -> mark#(s(X)) -> mark#(X)
    mark#(cons(X1,X2)) -> mark#(X1) -> mark#(2nd(X)) -> mark#(X)
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(2nd(X)) -> a__2nd#(mark(X))
    mark#(cons(X1,X2)) -> mark#(X1) -> mark#(from(X)) -> mark#(X)
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(from(X)) -> a__from#(mark(X))
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(cons(X1,X2)) -> mark#(X1)
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(s(X)) -> mark#(X)
    a__2nd#(cons(X,cons(Y,Z))) -> mark#(Y) ->
    mark#(2nd(X)) -> mark#(X)
    a__2nd#(cons(X,cons(Y,Z))) -> mark#(Y) ->
    mark#(2nd(X)) -> a__2nd#(mark(X))
    a__2nd#(cons(X,cons(Y,Z))) -> mark#(Y) ->
    mark#(from(X)) -> mark#(X)
    a__2nd#(cons(X,cons(Y,Z))) -> mark#(Y) ->
    mark#(from(X)) -> a__from#(mark(X))
    a__2nd#(cons(X,cons(Y,Z))) -> mark#(Y) ->
    mark#(cons(X1,X2)) -> mark#(X1)
    a__2nd#(cons(X,cons(Y,Z))) -> mark#(Y) -> mark#(s(X)) -> mark#(X)
   SCC Processor:
    #sccs: 1
    #rules: 8
    #arcs: 38/64
    DPs:
     a__from#(X) -> mark#(X)
     mark#(s(X)) -> mark#(X)
     mark#(cons(X1,X2)) -> mark#(X1)
     mark#(from(X)) -> a__from#(mark(X))
     mark#(from(X)) -> mark#(X)
     mark#(2nd(X)) -> a__2nd#(mark(X))
     a__2nd#(cons(X,cons(Y,Z))) -> mark#(Y)
     mark#(2nd(X)) -> mark#(X)
    TRS:
     a__2nd(cons(X,cons(Y,Z))) -> mark(Y)
     a__from(X) -> cons(mark(X),from(s(X)))
     mark(2nd(X)) -> a__2nd(mark(X))
     mark(from(X)) -> a__from(mark(X))
     mark(cons(X1,X2)) -> cons(mark(X1),X2)
     mark(s(X)) -> s(mark(X))
     a__2nd(X) -> 2nd(X)
     a__from(X) -> from(X)
    Open