Utility possibilities frontier-Curve showing all efficient allocations of resources measured in terms of the utility levels of two individuals. Social welfare function-Weights applied to each individual's utility in determining what is socially desirable. The second theorem of Welfare economics-if individual preferences are convex,then every efficient allocation (every point on the contract)is a competitive equilibrium for some initial allocation of goods.  Utility possibilities frontier - Curve showing all efficient allocations of resources measured in terms of the utility levels of two individuals.  Social welfare function -Weights applied to each individual’s utility in determining what is socially desirable.  The second theorem of Welfare economics—if individual preferences are convex, then every efficient allocation (every point on the contract) is a competitive equilibrium for some initial allocation of goods