The paper uses standard concepts of equilibrium and efficiency to analyze certain properties of the telephone system. The property of access/no access plays a central role in the analysis, and it is suggested that many so-called "systems" in modern life have similar access/no access properties.

Many marketing problems are usually analysed in verbal terms only. For instance, different alternatives as regards the marketing routes, or channels, through which goods and services or their titles flow, are mostly considered in terms of "advantages" and "disadvantages". Recently, however,...