Market Games

The key to a market is its implementation and efficient outcomes are not guaranteed under strategic behaviour. The talk elaborates on this basic thesis.

Markets are of course, one of the oldest mechanism of exchanging
commodities and cultural artifacts. While their history is over 5000 years old, their mathematical theory is rather recent. The first such models were by Fisher, Condorcet and Walras. Later models have been by Arrow, Debreu and others. Markets are now the central philosophical cornerstone of much of the discourse on efficiency and development, and it is imperative that we should investigate their functioning.

We do this by evaluating markets as startegic interactions between agents and then examine their allocations from the efficiency veiwpoint. We begin with the classical supply-demand curve price discovery mechanism. We see that a simple variation is already very instructive for analysing online markets.

The meat of the talk is the analysis of Fisher markets, a simple model of buyers with money and utilities, and sellers with goods. The standard efficient-market hypothesis predicts that unique prices are discovered and the market clears. We study this market under strategic behaviour by buyers who may report fictitious utlities. We show, in fact, that buyers may actually benefit from such behaviour. We then formulate the Fisher market game and examine its Nash equilibria and show some not-so-surprising features.

Finally, we look at some stylized market games and point to some
directions of research.