The Welfare Theorems

From Quasi- to Competitive Equilibrium

Theorem. Suppose that $(x^*,y^*,p^*)$ is a quasi-equilibrium for the private ownership economy $\mathcal{E}$. Suppose that for all consumers $n$ and for all $x_n\in X_n$, the set $\succ_n(x_n)$ is open. If each $w^*_n=p^*x^*_n\geq0$, then $(x^*,y^*,p^*,w^*)$ is a competitive equilibrium with transfers.

Proof. This is an immediate consequence of the definition of a quasi-equilibrium and the cheaper point Lemma.

The cheaper point assumption is automatically satisfied for interior optima, each $x^*_n\gg0$. what about boundary optima?