MAYBE
* Step 1: Failure MAYBE
  + Considered Problem:
      - Strict TRS:
          activate(X) -> X
          activate(n__add(X1,X2)) -> add(activate(X1),activate(X2))
          activate(n__from(X)) -> from(activate(X))
          activate(n__fst(X1,X2)) -> fst(activate(X1),activate(X2))
          activate(n__len(X)) -> len(activate(X))
          activate(n__s(X)) -> s(X)
          add(X1,X2) -> n__add(X1,X2)
          add(0(),X) -> X
          add(s(X),Y) -> s(n__add(activate(X),Y))
          from(X) -> cons(X,n__from(n__s(X)))
          from(X) -> n__from(X)
          fst(X1,X2) -> n__fst(X1,X2)
          fst(0(),Z) -> nil()
          fst(s(X),cons(Y,Z)) -> cons(Y,n__fst(activate(X),activate(Z)))
          len(X) -> n__len(X)
          len(cons(X,Z)) -> s(n__len(activate(Z)))
          len(nil()) -> 0()
          s(X) -> n__s(X)
      - Signature:
          {activate/1,add/2,from/1,fst/2,len/1,s/1} / {0/0,cons/2,n__add/2,n__from/1,n__fst/2,n__len/1,n__s/1,nil/0}
      - Obligation:
          innermost runtime complexity wrt. defined symbols {activate,add,from,fst,len,s} and constructors {0,cons
          ,n__add,n__from,n__fst,n__len,n__s,nil}
  + Applied Processor:
      NaturalPI {shape = Mixed 3, restrict = NoRestrict, uargs = UArgs, urules = URules, selector = Nothing}
  + Details:
      Incompatible
MAYBE