On Feb 7, 2005, at 5:15 AM, Henry Story wrote:
This is true only if you have the [Equivalence ID] interpretation of the id relation. (Ie you think of id as equivId.)
Yes, and to make myself perfectly clear, that means functional ID, as you call it, would conflict with the design of Atom and any reasonable design of a system wherein the things being identified are allowed to be updated over time.
I wonder if you read the rest of my message...
Yes, though it seems to me that you swapped the meanings of funcId and equivId somewhere between your definitions and your example, so I lost interest.
I gave an example that did not conflict with a reasonable design.
On the contrary, you gave an example in which a feed contained two entries with the same id (where id here is defined as meaning the author intends this entry to supplant any prior entries with the same id). It is not reasonable to include more than one entry with the same id within the same feed representation, since all entry representations in the feed representation must validly represent the state of the feed at the time that the feed representation was generated (otherwise, it is not a feed representation at all -- it is an archive, history, ... whatever).
This whole discussion presumes that it is not desirable to send all versions of all entries as part of the feed; i.e., the author specifically intends old versions of an entry to never appear in later versions of the feed. If you don't agree with that presumption, then I think you are talking about something other than what most bloggers call a feed.
So, please, stop trying to make a real system fit an artificial model of graph theory that isn't even capable of describing the Web. Fix your model instead.
Do you have a good paper that proves your incredibly strong statement above? I would be happy to understand this position, as it would save me a lot of time.
Okay, but only if you promise not to extend this discussion on the atom list -- take it elsewhere if you wish to puncture my opinion -- atom should be allowed to progress in peace without invoking the defenders of RDF universality.
<http://www.w3.org/TR/rdf-mt/#intro>:
There are several aspects of meaning in RDF which are ignored by this semantics; in particular, it treats URI references as simple names, ignoring aspects of meaning encoded in particular URI forms [RFC 2396] and does not provide any analysis of time-varying data or of changes to URI references. It does not provide any analysis of indexical uses of URI references, for example to mean 'this document'. Some parts of the RDF and RDFS vocabularies are not assigned any formal meaning, and in some cases, notably the reification and container vocabularies, it assigns less meaning than one might expect. These cases are noted in the text and the limitations discussed in more detail. RDF is an assertional logic, in which each triple expresses a simple proposition. This imposes a fairly strict monotonic discipline on the language, so that it cannot express closed-world assumptions, local default preferences, and several other commonly used non-monotonic constructs.
RDF has no capacity for temporally qualified assertions, no conceptual understanding of sink-like services, and very little habit of distinguishing between resources and representations (though it does have the capacity to deal with representations as b-nodes). Likewise, it does not differentiate between identification and use, which means it cannot be used to describe the many times in which a single URI can be used for many different things even if it only identifies (directly) one thing. The same comments apply to OWL.
As previously stated, understanding the meaning of a resource is all about time. Trying to describe the Web without that dimension is a hopelessly futile effort that leads to such absurdities as declaring some URIs as being "invalid" or "inappropriate" simply because their use does not fit the artificial model of a timeless world.
But I can't just take your word for it, as there are numerous people who don't seem to think the way you do, and in just as senior or more senior positions than your are.
My position is not based on seniority.
But perhaps
I have missed some important development recently. (I am not being ironic here though it may sound like it. I really would like to
understand more fully your position.)
No, as far as I know, there have been no recent developments that would cause the semantic web to reconsider its central assumptions.
Cheers,
Roy T. Fielding <http://roy.gbiv.com/> Chief Scientist, Day Software <http://www.day.com/>
