One labelled backwards. A single, bidirectional link that points to all related pages. In XLink I just list them all as the anchors of a link. This is a critical reduction in redundancy. I need at least n arcs FROM the reified topic and n arcs TO the reified topic.
All directions are traversable.
That's simply not true. The UI implementation is traversal based. Again, I can't even implement this using the model you define. I can get from the topic element to the related elements, but I can't get from the related things to the topic. In the implementation it is bidirectional.