 Levels of Obligation (LO): \(\phi_{x,t}\) is a life sequence from t for x. Every \(\phi_{x,t}\) has a rank \(n (n \ge 1)\) relative to every other life-sequence from t for x, where n is a positive integer. If \(\phi_{x,t}\) is among the optimum life sequences from t for x, then the rank of \(\phi_{x,t} = 1\); if \(\phi_{x,t}\) is among the second best such sequences, then the rank of \(\phi_{x,t} = 2\); and so on. x ought\(_n\) at t to do \(A_i\) iff: