Any set of commodities closely related in consumption and/or in production may be regarded as differentiated products. Close relation in consumption depends on consumers' tastes. Elementary scientific methodology tells that theories aspiring to empirical relevance must be consistent with the...

We investigate the origins of identity and the innate proclivity to draw a distinction between `insiders' and `outsiders'. We propose an evolutionary explanation: we argue that identity arises because it facilitates survival. In an evolutionary setting we endogenize preferences and demonstrate...

We analyze the success of filtering as a solution to the spam problem when used alone or concurrently with sender pricing, receiver pricing, or both. We find that filtering alone may exacerbate the spam problem in terms of both the total number of spam message sent and the expected number of...

This is a unique account of the role played by 58 figures and diagrams commonly used in economic theory. These cover a large part of mainstream economic analysis, both microeconomics and macroeconomics and also general equilibrium theory.

In their efforts to create and maintain a position in a market, firms make positioning investments of various sorts, in R&D, plant, advertising, and location, or more generally, in product development and maintenance. In an environment where the success of positioning investments is stochastic,...

We explore the link between affluence and well-being using a simple general equilibrium model with a pure Veblen good. Individuals derive utility from the pure Veblen good based solely on how much they consume relative to others. In equilibrium, consumption of the pure Veblen good is the same...