(VAR L N V V1 V2 )
(STRATEGY CONTEXTSENSITIVE
        (zeros ) 
        (cons 1) 
        (0 ) 
        (U11 1) 
        (tt ) 
        (U21 1) 
        (U31 1) 
        (U41 1) 
        (U42 1) 
        (isNatIList ) 
        (U51 1) 
        (U52 1) 
        (isNatList ) 
        (U61 1) 
        (U62 1) 
        (isNat ) 
        (s 1) 
        (length 1) 
        (nil ) 
)
(RULES 
        zeros -> cons(0, zeros)
        U11(tt) -> tt
        U21(tt) -> tt
        U31(tt) -> tt
        U41(tt, V2) -> U42(isNatIList(V2))
        U42(tt) -> tt
        U51(tt, V2) -> U52(isNatList(V2))
        U52(tt) -> tt
        U61(tt, L, N) -> U62(isNat(N), L)
        U62(tt, L) -> s(length(L))
        isNat(0) -> tt
        isNat(length(V1)) -> U11(isNatList(V1))
        isNat(s(V1)) -> U21(isNat(V1))
        isNatIList(V) -> U31(isNatList(V))
        isNatIList(zeros) -> tt
        isNatIList(cons(V1, V2)) -> U41(isNat(V1), V2)
        isNatList(nil) -> tt
        isNatList(cons(V1, V2)) -> U51(isNat(V1), V2)
        length(nil) -> 0
        length(cons(N, L)) -> U61(isNatList(L), L, N)
        
)