For a tolled highway where consecutive sections allow vehicles enter and exit unrestrictedly, we propose a simple toll pricing method. We show that the method is the unique method that satisfies the properties of Transit-proofness (No Merging or Splitting) and Cost Recovery. The...

We analyze optimal trading mechanisms in an exchange economy where each trader owns some units of a good to be traded and may be either a seller or a buyer, depending on the realization of the privately observed valuations. The concept of virtual valuation is extended to ex ante unidentified...