Computable Economic Analysis

This paper discusses an economic equilibrium theory with computabil-ity constraints on both the magnitudes (prices, quantities, etc.) and the operations (to perceive, evaluate, choose, communicate, etc) that agents can use. Prices and quantities are computable numbers (Turing (1936)), and preference relations, utility functions, demand functions are computable (in the sense of Moschovakis (1964)). We present sharper versions of several traditional assertions on utility representation , existence of consumer demand functions, the fundamental welfare theorems, characterizations of market excess demands. We also give a \computable coun-terexample" to the existence of a competitive equilibrium. These results can be interpreted as possibility and impossibility results in computability-bounded ratio-nality, and in computational economics.