Corollary 2

— A family $(a_i)$ of points of $F$ is topologically independent for the topology $\sigma(F, G)$, if, and only if, for every index $i$, there exists an element $b_i \in G$ such that : $\langle a_i, b_i \rangle \neq 0$ and $\langle a_\kappa, b_i \rangle = 0$ for all $\kappa \neq i$.

This means, that for all $i$, there exists a closed hyperplane in $\sigma(F, G)$, which contains all the $a_\kappa$ with index $\kappa \neq i$ but does not contain $a_i$.