MAYBE MAYBE TRS: { sqr(s(X)) -> s(add(sqr(X), dbl(X))), sqr(0()) -> 0(), terms(N) -> cons(recip(sqr(N)), n__terms(s(N))), terms(X) -> n__terms(X), add(s(X), Y) -> s(add(X, Y)), add(0(), X) -> X, dbl(s(X)) -> s(s(dbl(X))), dbl(0()) -> 0(), first(X1, X2) -> n__first(X1, X2), first(s(X), cons(Y, Z)) -> cons(Y, n__first(X, activate(Z))), first(0(), X) -> nil(), activate(X) -> X, activate(n__terms(X)) -> terms(X), activate(n__first(X1, X2)) -> first(X1, X2), half(s(s(X))) -> s(half(X)), half(s(0())) -> 0(), half(0()) -> 0(), half(dbl(X)) -> X } DUP: We consider a duplicating system. Trs: { sqr(s(X)) -> s(add(sqr(X), dbl(X))), sqr(0()) -> 0(), terms(N) -> cons(recip(sqr(N)), n__terms(s(N))), terms(X) -> n__terms(X), add(s(X), Y) -> s(add(X, Y)), add(0(), X) -> X, dbl(s(X)) -> s(s(dbl(X))), dbl(0()) -> 0(), first(X1, X2) -> n__first(X1, X2), first(s(X), cons(Y, Z)) -> cons(Y, n__first(X, activate(Z))), first(0(), X) -> nil(), activate(X) -> X, activate(n__terms(X)) -> terms(X), activate(n__first(X1, X2)) -> first(X1, X2), half(s(s(X))) -> s(half(X)), half(s(0())) -> 0(), half(0()) -> 0(), half(dbl(X)) -> X } Fail