Re: cwm/n3 and naming blank nodes? (calendar rules)

Norm Walsh asked, back on 1Dec...
http://lists.w3.org/Archives/Public/www-rdf-interest/2002Dec/0002.html

about rules for repeating events, some with
end markers and some without.

I completely missed that message, as I only catch
up with www-rdf-interest occasionally, but meanwhile, in
www-rdf-calendar, I wrote some rules that, I think,
answer Norm's question.

futureEvents.n3: an excercise in processing recurring events
Dan Connolly (Thu, Dec 19 2002)
http://lists.w3.org/Archives/Public/www-rdf-calendar/2002Dec/0022.html

Applying the lessons from futureEvents to Norm's birthday
case, we get:

this log:forAll :p, :s, :o, :t, :u, :l, :k, :m, :E.

{ :p a ab:Contact;
    p:born :o } log:implies { :p :birthEvent [ a db:Appointment ;
                                   db:begin-date :o ;
                                   db:repeat [
                                      rdf:type db:Repeat ;
                                      db:frequency "1";
                                      db:type "Yearly" ] ] } .

{ :p a ab:Contact;
    p:born :o;
    p:died :s;
    :birthEvent :E } log:implies { :E db:end :s }.


There's something unsatisfying about this style of rules...
it feels procedural -- I start to think about
"creating" a db:Appointment and "modifying" it --
while writing rules is supposed to be declarative.

I'm not really modifying anything; this is all monotonic.
But feels wierd.

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/