Simon Grant wrote:

>> For instance if a book has been published several times,
 >> it's publication date is a set of dates.
> How do you square this with FRBR?

I was not talking about FRBR but trying to answer your question. By the 
way I wonder how FRBR squares with reality - but FRBR is not the topic.

> I wouldn't take seriously any proposed single entity with a
> publication set of dates. Doesn't this mean that the entity
 > covers a set of other things each with their own publication date?

No it doesn't. The choice what makes an entity is arbitrary and always 
an oversimplification of reality. If you don't want things to have 
multiple dates, you don't have to allow it, but either choice is not 

> In which case, we have still not found a practical example of an entity
> which, in its own right, has a set of dates as an attribute.

Q: "When did this band play in your town?"
A: "They gave a concert at 2nd and 3rd June"
Q: "Oh, they started playing at 2nd and finished at 3rd?"
A: "No, they gave two shows, one at 2nd, one at 3rd."
Q: "But which date did they play?"
A: "At 2nd, and 3rd, as I said."
Q: "But '2nd and 3rd' is not a date!"
A: "You definitely spent too much time with date formats!"


P.S: Unless you try to relate sets of dates as "equal to" other 
concepts, like intervals, durations and single dates, the question 
whether to allow sets of dates is independent from other aspects, 
anyway. I would also forbid sets of cardinality less than two, to
avoid more difficult questions.

Jakob Voß <[log in to unmask]>, skype: nichtich
Verbundzentrale des GBV (VZG) / Common Library Network
Platz der Goettinger Sieben 1, 37073 Göttingen, Germany
+49 (0)551 39-10242,