On The Social Efficiency In Monopolistic Competitioin Models

We consider standard monopolistic competition models with aggregate consumer's preferences dened by two well-known classes of utility functions | the Kimball utility function and the variable elasticity of substitution utility function. It is known that market equilibruim is ecient only for the special case when utility function has a constant elasticity of substitution, but we nd that in both cases a special tax on rms' output may be introduced such that market equilibrium becomes ecient