while(already_processed < front) {
// Here, nodes before already_processed can be ignored, nodes
// before front were set to 0 predecessors during the previous
- // iteration. We will add the
+ // iteration. During this new iteration, we have to visit the
+ // successors of these ones only, since they are the only ones
+ // potentially having now predecessors anymore.
new_front = front;
while(already_processed < front) {
v = *(already_processed++);