(VAR N M X)
(RULES 
U11(tt) -> U12(isNat)
U12(tt) -> U13(isNat)
U13(tt) -> tt
U21(tt) -> U22(isNat)
U22(tt) -> tt
U31(tt) -> U32(isNat)
U32(tt) -> U33(isNat)
U33(tt) -> tt
U41(tt) -> N
U51(tt) -> s(plus(N,M))
U61(tt) -> 0
U71(tt) -> plus(x(N,M),N)
and(tt) -> X
isNat -> tt
isNat -> U11(and(isNatKind))
isNat -> U21(isNatKind)
isNat -> U31(and(isNatKind))
isNatKind -> tt
isNatKind -> and(isNatKind)
isNatKind -> isNatKind
isNatKind -> and(isNatKind)
plus(N,0) -> U41(and(isNat))
plus(N,s(M)) -> U51(and(and(isNat)))
x(N,0) -> U61(and(isNat))
x(N,s(M)) -> U71(and(and(isNat)))
)