When we think about taxonomy terms in Drupal (as opposed to nodes), we think about hierarchy: parents, children, and relationships.  If we were to draw out these relationships on paper, we'd wind up with a series of dots connected by lines--also called a "graph".  By using mathematical graph theory to describe these relationships, we can make your site more efficient, more intelligent, and more fun!

This talk will focus on general ideas and practical advice, and only include the bare minimum mathematics needed to illustrate my points.