Chapter 4 Non Walrasian equilibria money and macroeconomics Non Walrasian equilibria also called equilibria with rationing are a wide class of equilibrium concepts that generalize the traditional notion of Walrasian equilibrium by allowing markets not to clear and emphasizing quantity rationing. In Walrasian equilibrium total demand equals total supply for each good. This consistency of the actions of all agents is achieved by price movements in the manner in which all private agents receive a price signal and assume that they will be able to exchange whatever they want at that price system. A Walrasian equilibrium price system is a set of prices for which total demand and total supply are equal in all markets. Transactions are equal to the demands and supplies at this price system. Money can be interpreted as commodity money. But the recent evolution of money tends to privilege the interpretation of money as fiat money that is a costlessly produced legal medium of exchange. This chapter discusses simple macroeconomic applications of the microeconomic concepts and presents a micromacro model of imperfect competition and unemployment.