Ranking indirect connections in literature-based discovery: The role of medical subject headings

search.) If there are no articles within the AC intersection, an intriguing question arises as to whether there might exist implicit or indirect connections between A and C based, for example, on an intermediate literature (B) for which both an AB relationship and a BC relationship have already been separately reported, but perhaps not considered together. It is usually pointless or at least inefficient to pursue indirect connections before conducting a broadly based literature search for direct connections and analyzing the relevant findings. Any direct connections that exist may eliminate or greatly change the problem and significance of indirect connections.