The model is an open one related to the partial equilibrium models of
much of micro-economics. In particular money and its acceptance in
trade is taken as a primitive concept. There is a literature on the
acceptance of money both in a static equilibrium context (see for
example [2]) and in a "bootstrap" or dynamic
context (see for example [3,4]). These
are extremely simple closed models of the economy where each
individual is both a buyer and seller. Eventually we would like to
construct a reasonable model where the acceptance of money, the
emergence of competitive price and the emergence of market structure
all arise from the system dynamics. This will call for an appropriate
combination of the features of the model presented here with the
closed models noted above. We do not pursue this further here.
Instead by taking the acceptance of money as given our observations
are confined to the emergence of markets and the nature of price. The
static economic theories of monopoly and mass homogeneous competitive
equilibrium provide natural upper and lower benchmarks to gauge market
behavior. The intermediate zone between 
and very many is
covered in the economic literature by various oligopoly models, of
which those of Cournot [5], Bertrand [6]
and Chamberlin [7] serve as exemplars. The
Chamberlin model unlike the earlier models stresses that all firms
trade in differentiated goods. They are all in part differentiated or
partially monopolistic. When one considers both information and
physical location this is a considerable step towards greater realism.
Other work on evolutionary or behavioral learning in price formation
are Refs. [8,9,10].