Different kinds of identifiers

[draggett]

In natural language, we have some words with a widely agreed meaning - these are words you can look up in a dictionary. We also have names that can only be resolved in context, e.g. my friends know me as Dave, but there are lots of other people called Dave. In yet other cases you are given a description rather than a name, e.g. the third door on the left.

RDF should allow for the same flexibility.

The first category correspond to URIs for concepts with a widely shared meaning.

The second category are a little harder as when you hear that someone is called Dave you don't immediately know unambiguously which person that is. You could assign an identifier to the hypothetical person along with a triple asserting that that person's name is Dave. Later, you may work out that this person is actually someone you already know, or perhaps learn about another Dave who likewise you aren't sure who he is, and may want to consider whether he is the same as the first Dave.

I think this is easier to deal with if we allow for identifiers scoped to a context like a graph and this makes such identifiers easier to manage. Consider how you might want to represent narratives that define a hypothetical reality and inherit what you know about the real world. Blank nodes give us this flexibility.

The third category can be considered in term of path queries. Here each branch in the path may involve a locally scoped identifier for a path from a given node. This is analogous to the names of object properties in object oriented programming languages. Such locally scoped names may or may not be associated with globally agreed meanings (the first category).

How can RDF support such variations in an easy to understand way?