Definition (Team-optimal solution)

For a given stochastic team problem with a fixed information structure $\{ J;\Gamma^{i},i\in\mathcal{N}\}$, a policy $N-$tuple $$\underline{\gamma}^{*}=(\gamma^{1*},\dots,\gamma^{N*})\in\mathbf{\Gamma}$$is a team-optimal solution if $$J(\underline{\gamma}^{*})=\inf_{\underline{\gamma}\in\Gamma}J(\underline{\gamma})=:J^{*}$$provided that the strategy exists. The cost level achieved by this strategy, $J^{*}$, is the minimum (or optimal) team cost.