  The heart of both sets of ideas is the notion of clustering items by similarity. The algorithms for clustering into formal concepts are the same as the algorithms for preliminary groupings by similarity for the purpose of automatically generating hypotheses. As it turns out, and as Kuznetsov has shown, these algorithms are equivalent in their effect to algorithms for finding the maximal complete subgraphs of arbitrary graphs. This fact has proved extremely useful in recent years, since the latter algorithms are the core of what has come to be known as “Social Network Analysis.” And Social Network Analysis has become a major intellectual tool in the world’s battles against criminal organizations and terrorist networks. So all three sets of ideas have become matters of crucial practical importance and even urgency in contemporary affairs.