MAYBE MAYBE TRS: { app(X1, X2) -> n__app(X1, X2), app(nil(), YS) -> YS, app(cons(X, XS), YS) -> cons(X, n__app(activate(XS), YS)), nil() -> n__nil(), activate(X) -> X, activate(n__app(X1, X2)) -> app(X1, X2), activate(n__from(X)) -> from(X), activate(n__nil()) -> nil(), activate(n__zWadr(X1, X2)) -> zWadr(X1, X2), from(X) -> cons(X, n__from(s(X))), from(X) -> n__from(X), zWadr(XS, nil()) -> nil(), zWadr(X1, X2) -> n__zWadr(X1, X2), zWadr(nil(), YS) -> nil(), zWadr(cons(X, XS), cons(Y, YS)) -> cons(app(Y, cons(X, n__nil())), n__zWadr(activate(XS), activate(YS))), prefix(L) -> cons(nil(), n__zWadr(L, prefix(L))) } DUP: We consider a duplicating system. Trs: { app(X1, X2) -> n__app(X1, X2), app(nil(), YS) -> YS, app(cons(X, XS), YS) -> cons(X, n__app(activate(XS), YS)), nil() -> n__nil(), activate(X) -> X, activate(n__app(X1, X2)) -> app(X1, X2), activate(n__from(X)) -> from(X), activate(n__nil()) -> nil(), activate(n__zWadr(X1, X2)) -> zWadr(X1, X2), from(X) -> cons(X, n__from(s(X))), from(X) -> n__from(X), zWadr(XS, nil()) -> nil(), zWadr(X1, X2) -> n__zWadr(X1, X2), zWadr(nil(), YS) -> nil(), zWadr(cons(X, XS), cons(Y, YS)) -> cons(app(Y, cons(X, n__nil())), n__zWadr(activate(XS), activate(YS))), prefix(L) -> cons(nil(), n__zWadr(L, prefix(L))) } Fail