Weak domination in second-price sealed-bid action:-
Show that for each type vi of each player i in a second-price sealed-bid auction with imperfect information about valuations the bid vi weakly dominates all other bids. We conclude, in particular, that a second-price sealed-bid auction with imperfect information about valuations has a Nash equilibrium in which every type of every player bids her valuation. The game has also other equilibria, some of which you are asked to find in the next exercise.