What the grouping severed

Topic categories form a graph, not a tree: the strongest relationships in this corpus cut across any grouping. These pairs clear the relatedness bar (at least 25 shared papers and 2.0× the co-occurrence chance predicts) yet sit in different areas, so browsing the hierarchy alone will not reveal them. They are listed here rather than quietly dropped.

The full pair table, with thresholds, is published at /machine/affinity.json.