MAYBE MAYBE TRS: { sqr(s(X)) -> s(add(sqr(X), dbl(X))), sqr(0()) -> 0(), terms(N) -> cons(recip(sqr(N)), terms(s(N))), add(s(X), Y) -> s(add(X, Y)), add(0(), X) -> X, dbl(s(X)) -> s(s(dbl(X))), dbl(0()) -> 0(), first(s(X), cons(Y, Z)) -> cons(Y, first(X, Z)), first(0(), X) -> nil() } 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)), terms(s(N))), add(s(X), Y) -> s(add(X, Y)), add(0(), X) -> X, dbl(s(X)) -> s(s(dbl(X))), dbl(0()) -> 0(), first(s(X), cons(Y, Z)) -> cons(Y, first(X, Z)), first(0(), X) -> nil() } Fail