Semantic Web

What must it represent?

Perhaps not much

... a large majority of the information we want to express is along the lines of "a hex-head bolt is a type of machine bolt ...." Berners-Lee 2001

In RDF, a document makes assertions that particular things (people, Web pages or whatever) have properties (such as "is a sister of," "is the author of") with certain values (another person, another Web page). This structure turns out to be a natural way to describe the vast majority of the data processed by machines. Berners-Lee 2001

If so, then

All ambiguity is lexical! (Cf. Tip O'Neill.)