Before revision:  However, these methods do not apply to the generalized problems. We showed that such problems are still tractable , and can be solved efficiently as conic programs.
After revision:  However, these methods do not apply to the generalized problem. We show that the generalized problem is still tractable under the multinomial logit (MNL), the nested logit (NL) and the Markov chain (MC) choice model. Such problems can still be transformed into convex programs , and can be solved efficiently as conic programs.