Fig. 1.

A pseudostable tuple T_i in (a) and a multiple pseudostable tuple M_i in (b). Both sets D₁ and D₂ are stable and some blue paths of length 3 exist between both. The sets $\mathfrak{P}\left(T_i\right)$ and $\mathfrak{P}\left(M_i\right)$ consist of all blue nodes which are neither in D₁ nor in D₂