XML.com: An Introduction to FOAF
XML.com: An Introduction to FOAF: "That's because there is still some debate around both the social and technical implications of assigning URIs to people. Which URI identifies you? Who assigns these URIs? What problems are associated with having multiple URIs (assigned by different people) for the same person? Side-stepping this potential minefield, FOAF borrows the concept of an 'inverse functional property' (IFP) from OWL, the Web Ontology Language. An inverse functional property is simply a property whose value uniquely identifies a resource."