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