ABSTRACT
In contemporary societies, multi-person games are often governed by formal rules designed to ensure that the outcomes are fair and democratic. Within this broad category is an important class of games that serve the purpose of aggregating individual preferences into collective choices. For example, committees often have to choose a single course of action from among several proposals favoured by different members. A method of resolving differences of opinion into a specific choice from a set of alternatives or candidates is called a social choice function (or a social choice rule), and those that have a claim to being fair and democratic are generally voting procedures of one kind or another. Voting procedures are used by electorates for choosing political representatives, by legislatures for choosing laws, by colleges of cardinals for choosing popes, and by juries, boards of directors in industry, groups of shareholders, trade unions, and many other kinds of committees and decision-making bodies.
