TRS: { a__U11(tt(), N) -> mark(N), a__U21(tt(), M, N) -> s(a__plus(mark(N), mark(M))), a__and(tt(), X) -> mark(X), a__isNat(0()) -> tt(), a__isNat(plus(V1, V2)) -> a__and(a__isNat(V1), isNat(V2)), a__isNat(s(V1)) -> a__isNat(V1), a__plus(N, 0()) -> a__U11(a__isNat(N), N), a__plus(N, s(M)) -> a__U21(a__and(a__isNat(M), isNat(N)), M, N), mark(U11(X1, X2)) -> a__U11(mark(X1), X2), mark(U21(X1, X2, X3)) -> a__U21(mark(X1), X2, X3), mark(plus(X1, X2)) -> a__plus(mark(X1), mark(X2)), mark(and(X1, X2)) -> a__and(mark(X1), X2), mark(isNat(X)) -> a__isNat(X), mark(tt()) -> tt(), mark(s(X)) -> s(mark(X)), mark(0()) -> 0(), a__U11(X1, X2) -> U11(X1, X2), a__U21(X1, X2, X3) -> U21(X1, X2, X3), a__plus(X1, X2) -> plus(X1, X2), a__and(X1, X2) -> and(X1, X2), a__isNat(X) -> isNat(X)} Fail