1. A method comprising: generating buyer decision information by presenting a sequence of sale offer menus to a sequence of buyers and conducting actual sale transactions based on sale offers accepted by buyers; and at a selected time in the generating, updating a buyer valuation distribution belief and the current sale offer menu of the sequence of sale offer menus to optimize a buyer's utility comprising a buyer's utility function constrained by a robust learning constraint that is computed based on a local differential of an earlier buyers utility function with respect to the earlier buyer's valuation, the robust learning constraint bounding a rate of change of the later buyer's utility based on the local curvature of the earlier buyer's utility function at the earlier buyer's valuation; wherein the generating and the updating operations are performed by a digital processor.