Département d'Informatique

\begin{equation}
\bar{S}_n^{Inter} =
\frac{\overset {n} {\underset{a=1} {\sum}}
\overset {n} {\underset{b=a+1} {\sum}}
(\frac{\overset {L_a} {\underset{i=1} {\sum}}
\overset {L_b} {\underset{j=1} {\sum}} \; D(v_i^a,v_j^b)}
{L_a \times L_b})
}
{n(n-1)}
\end{equation}