Past exam of the mathematics course of the University of Cambridge 2013 iii Paper 39 4 c Solution Created 2026-10-03 Updated 2026-10-07
Let be the optimal expected value before seeing the next offer when rounds remain. With one round left the offer must be accepted, so . For , observing gives a choice between now and the continuation value . Independence of future uniform distributions makes that continuation value independent of past offers. Thus the uniform-offer stopping recursion isIt gives and . The Snell envelope rule therefore yields the explicit strategyOnly rounds actually reached are played. At a threshold the two actions have identical continuation expected value; either convention is optimal, and exact equality has probability zero. The optimal expected payout before the first offer is