MAYBE

'Pop* with parameter subtitution (timeout of 60.0 seconds)'
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Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  U11(tt(), N, XS) -> U12(tt(), activate(N), activate(XS))
     , U12(tt(), N, XS) -> snd(splitAt(activate(N), activate(XS)))
     , U21(tt(), X) -> U22(tt(), activate(X))
     , U22(tt(), X) -> activate(X)
     , U31(tt(), N) -> U32(tt(), activate(N))
     , U32(tt(), N) -> activate(N)
     , U41(tt(), N, XS) -> U42(tt(), activate(N), activate(XS))
     , U42(tt(), N, XS) -> head(afterNth(activate(N), activate(XS)))
     , U51(tt(), Y) -> U52(tt(), activate(Y))
     , U52(tt(), Y) -> activate(Y)
     , U61(tt(), N, X, XS) ->
       U62(tt(), activate(N), activate(X), activate(XS))
     , U62(tt(), N, X, XS) ->
       U63(tt(), activate(N), activate(X), activate(XS))
     , U63(tt(), N, X, XS) ->
       U64(splitAt(activate(N), activate(XS)), activate(X))
     , U64(pair(YS, ZS), X) -> pair(cons(activate(X), YS), ZS)
     , U71(tt(), XS) -> U72(tt(), activate(XS))
     , U72(tt(), XS) -> activate(XS)
     , U81(tt(), N, XS) -> U82(tt(), activate(N), activate(XS))
     , U82(tt(), N, XS) -> fst(splitAt(activate(N), activate(XS)))
     , afterNth(N, XS) -> U11(tt(), N, XS)
     , fst(pair(X, Y)) -> U21(tt(), X)
     , head(cons(N, XS)) -> U31(tt(), N)
     , natsFrom(N) -> cons(N, n__natsFrom(s(N)))
     , sel(N, XS) -> U41(tt(), N, XS)
     , snd(pair(X, Y)) -> U51(tt(), Y)
     , splitAt(0(), XS) -> pair(nil(), XS)
     , splitAt(s(N), cons(X, XS)) -> U61(tt(), N, X, activate(XS))
     , tail(cons(N, XS)) -> U71(tt(), activate(XS))
     , take(N, XS) -> U81(tt(), N, XS)
     , natsFrom(X) -> n__natsFrom(X)
     , activate(n__natsFrom(X)) -> natsFrom(X)
     , activate(X) -> X}

Proof Output:    
  The input cannot be shown compatible