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Baseball card market

A market many kids participate in is the ‘baseball card market’. This is the market in which children (agents) have baseball cards and are willing to trade said cards with each other. In the market I’m defining there is no real money, kids only trade cards for other cards. Because of this the currency is the cards themselves.


The market design in this market has several interesting properties. Each agent can own many baseball cards. In previous examples we have seen in class each agent only gets one recourse but in this each agent can have several. Another aspect of this market is that trades in the market don’t have to be one to one. For example, someone can trade 5 cards for one particularly valuable card. This market of course allows each agent to have preferences over all possible cards. When one considers that trades aren’t one to one its important to not only give agent preferences over all cards but to have agent preferences over all sets of cards.


Because preferences are over sets of cards it creates a really convoluted market. There would still be parento-efficient matchings but every other aspect of the market is significantly more complex then what we have seen so far. Serial dictatorships won’t work because of course everyone’s first preference is to have all the cards. In fact I can’t really think of a mechanism that fairly allocates cards and is strategy proof.


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