+ * If a constraint is not shared, the sum is replaced by a max.
+ * For example, a third non-shared constraint `cons3` and the associated elements `elem5` and `elem6` could write as:
+ *
+ * max( var1.weight * var1.value * elem5.value , var3.weight * var3.value * elem6.value ) <= cons3.bound
+ *
+ * This is usefull for the sharing of resources for various models.
+ * For instance, for the network model, each link is associated
+ * to a constraint and each communication to a variable.