MAYBE MAYBE TRS: { cons(mark(X1), X2) -> mark(cons(X1, X2)), cons(ok(X1), ok(X2)) -> ok(cons(X1, X2)), active(cons(X1, X2)) -> cons(active(X1), X2), active(zeros()) -> mark(cons(0(), zeros())), active(and(X1, X2)) -> and(active(X1), X2), active(and(tt(), X)) -> mark(X), active(length(X)) -> length(active(X)), active(length(cons(N, L))) -> mark(s(length(L))), active(length(nil())) -> mark(0()), active(s(X)) -> s(active(X)), and(mark(X1), X2) -> mark(and(X1, X2)), and(ok(X1), ok(X2)) -> ok(and(X1, X2)), length(mark(X)) -> mark(length(X)), length(ok(X)) -> ok(length(X)), s(mark(X)) -> mark(s(X)), s(ok(X)) -> ok(s(X)), proper(cons(X1, X2)) -> cons(proper(X1), proper(X2)), proper(0()) -> ok(0()), proper(zeros()) -> ok(zeros()), proper(and(X1, X2)) -> and(proper(X1), proper(X2)), proper(tt()) -> ok(tt()), proper(length(X)) -> length(proper(X)), proper(nil()) -> ok(nil()), proper(s(X)) -> s(proper(X)), top(mark(X)) -> top(proper(X)), top(ok(X)) -> top(active(X)) } DUP: We consider a non-duplicating system. Trs: { cons(mark(X1), X2) -> mark(cons(X1, X2)), cons(ok(X1), ok(X2)) -> ok(cons(X1, X2)), active(cons(X1, X2)) -> cons(active(X1), X2), active(zeros()) -> mark(cons(0(), zeros())), active(and(X1, X2)) -> and(active(X1), X2), active(and(tt(), X)) -> mark(X), active(length(X)) -> length(active(X)), active(length(cons(N, L))) -> mark(s(length(L))), active(length(nil())) -> mark(0()), active(s(X)) -> s(active(X)), and(mark(X1), X2) -> mark(and(X1, X2)), and(ok(X1), ok(X2)) -> ok(and(X1, X2)), length(mark(X)) -> mark(length(X)), length(ok(X)) -> ok(length(X)), s(mark(X)) -> mark(s(X)), s(ok(X)) -> ok(s(X)), proper(cons(X1, X2)) -> cons(proper(X1), proper(X2)), proper(0()) -> ok(0()), proper(zeros()) -> ok(zeros()), proper(and(X1, X2)) -> and(proper(X1), proper(X2)), proper(tt()) -> ok(tt()), proper(length(X)) -> length(proper(X)), proper(nil()) -> ok(nil()), proper(s(X)) -> s(proper(X)), top(mark(X)) -> top(proper(X)), top(ok(X)) -> top(active(X)) } Fail