ABSTRACT
Even the most innocuous of economic choices are in principle very complicated. For example consider a shopper in a grocery store looking at rows of breakfast cereal and deciding which one to buy. Should she buy the cereal she usually buys? Should she try a new cereal the store has just introduced? Should she buy the cereal on special offer? Will the cereal she usually buys be on special offer next week? Will it be cheaper in another store? Should she be tempted by the cereal with the chance to win a holiday in the Caribbean?
