3) Similarly, in order to prove this property, we only need to , {u}) , i.e., for any t ≥ 0, the probability that t is located in T(u, {v}) equals the probability that t is located in 4) If S ⊂ T, in order to prove this property, we only need to prove T(u, S) ⊂ T(u, T ) and notice the fact that the infimum of a larger set is smaller.