Dynamic Random Choice

I study dynamic random utility with finite choice sets and exogenous total menu variation, which I refer to as stochastic utility (SU). First, I characterize SU when each choice set has three elements. Next, I prove several mathematical identities for joint, marginal, and conditional Block--Marschak sums, which I use to obtain two characterizations of SU when each choice set but the last has three elements. As a corollary under the same cardinality restrictions, I sharpen an axiom to obtain a characterization of SU with full support over preference tuples. I conclude by characterizing SU without cardinality restrictions. All of my results hold over an arbitrary finite discrete time horizon.