tree, because you can’t loop back on yourself. If you could loop back on yourself it would be known as a circuit This is interesting to think about in the context of your site, or an area of the link graph
to another node by searching for an edge-type combined with an input node. E.g.: ▪Your friends: friend:10003 ▪People who live in new york: lives-in:111 ▪People who like downtown abbey: like:222
or places that Google knows about—landmarks, celebrities, cities, sports teams, buildings, geographical features, movies, celestial objects, works of art and more—and instantly get information that’s relevant to your query. Amit Singhal, Google
changes in the way Google present results, not all of them are truly ‘Knowledge Graph’ but do indicate a general shift in the way they present results.