Sexism links to both philosophy and Ethiopia. It is treating links as an undirected graph (despite the visual indication showing a directional vector), which seems entirely fair.
It seems somewhat unfair. If it's not a directed graph, it means you can't actually navigate from the source to the target page by following these links...
edit: in fact, the author describes the goal of his project in another comment here: "my goal for the project which is to traverse the links as any human would be able to".
Every single example I can find makes it painfully clear it is an undirected graph. Sets may differ going from one direction to the other simply because it is only trying to find a sample set of correlations, not an exhaustive set.
The graph is most definitely directed. One small example is Facebook -> Narcissism (1 path of 1 degree)[1] compared to Narcissism -> Facebook (8 paths of 2 degrees)[2].
Philosophy links to neither sexism or "The Demographics of Africa" (and while some older version might link to sexism, it seems unlikely that it ever linked to the Demographics of Africa"). Both of those do link to Philosophy, however.
Alternately it is directed, except when it doesn't find an easy route and uses an undirected result.
