MAYBE
* Step 1: Failure MAYBE
  + Considered Problem:
      - Strict TRS:
          0() -> n__0()
          U11(tt()) -> tt()
          U21(tt()) -> tt()
          U31(tt()) -> tt()
          U41(tt(),V2) -> U42(isNatIList(activate(V2)))
          U42(tt()) -> tt()
          U51(tt(),V2) -> U52(isNatList(activate(V2)))
          U52(tt()) -> tt()
          U61(tt(),L,N) -> U62(isNat(activate(N)),activate(L))
          U62(tt(),L) -> s(length(activate(L)))
          activate(X) -> X
          activate(n__0()) -> 0()
          activate(n__cons(X1,X2)) -> cons(activate(X1),X2)
          activate(n__length(X)) -> length(activate(X))
          activate(n__nil()) -> nil()
          activate(n__s(X)) -> s(activate(X))
          activate(n__zeros()) -> zeros()
          cons(X1,X2) -> n__cons(X1,X2)
          isNat(n__0()) -> tt()
          isNat(n__length(V1)) -> U11(isNatList(activate(V1)))
          isNat(n__s(V1)) -> U21(isNat(activate(V1)))
          isNatIList(V) -> U31(isNatList(activate(V)))
          isNatIList(n__cons(V1,V2)) -> U41(isNat(activate(V1)),activate(V2))
          isNatIList(n__zeros()) -> tt()
          isNatList(n__cons(V1,V2)) -> U51(isNat(activate(V1)),activate(V2))
          isNatList(n__nil()) -> tt()
          length(X) -> n__length(X)
          length(cons(N,L)) -> U61(isNatList(activate(L)),activate(L),N)
          length(nil()) -> 0()
          nil() -> n__nil()
          s(X) -> n__s(X)
          zeros() -> cons(0(),n__zeros())
          zeros() -> n__zeros()
      - Signature:
          {0/0,U11/1,U21/1,U31/1,U41/2,U42/1,U51/2,U52/1,U61/3,U62/2,activate/1,cons/2,isNat/1,isNatIList/1
          ,isNatList/1,length/1,nil/0,s/1,zeros/0} / {n__0/0,n__cons/2,n__length/1,n__nil/0,n__s/1,n__zeros/0,tt/0}
      - Obligation:
          innermost runtime complexity wrt. defined symbols {0,U11,U21,U31,U41,U42,U51,U52,U61,U62,activate,cons,isNat
          ,isNatIList,isNatList,length,nil,s,zeros} and constructors {n__0,n__cons,n__length,n__nil,n__s,n__zeros,tt}
  + Applied Processor:
      NaturalPI {shape = Mixed 3, restrict = NoRestrict, uargs = UArgs, urules = URules, selector = Nothing}
  + Details:
      Incompatible
MAYBE