The Second Welfare Theorem. Let $(x^*,y^*)$ be a Pareto Optimal
allocation for a private ownership economy $\mathcal{E}$ with the properties that
- for all $n$, $X_n$ is convex,
- the sets $R(x^*_n)$ are convex,
- for some consumer $k$, $P(x^*_k)$ is convex and $\succeq_k$ is locally non-satiated at $x^*_k$,
- $Y$ is convex.
Then there is a $p^*$ such that $(x^*,y^*,p^*)$ is a quasi-equilibrium for $\mathcal{E}$.