Re: [TF-PP] Property Path FPWD

On 04/01/2010 12:31 PM, Ivan Herman wrote:
> Hi Andy,
>>> - I am not sure what "A path of length zero connects a graph node to
>>> itself." means in terms of a triple pattern...
>>
>> ?x :p* ?y needs a meaning.  :p* can appear in more complex paths
>> (rdf:first*/rdf:rest).
>>
>> Working backwards from e.g. ?list rdf:first*/rdf:rest ?elt, ?list
>> rdf:first* ?x would match with ?x equal to whatever ?list is.
>>
>
> Hm. Alternatively, ?x :p* ?y would not match anything with length zero?

Then ?list rdf:rest* ?elt does not match the beginning cell of a list and

   ?list rdf:rest*/rdf:first ?elt

(which eventually I will write correctly!)

does not find the first element of a list without making :p* different 
from the :p* in :p*/:q

It does have a nice effect that

   :C rdfs:subClassOf ?class

includes :C (as per inference rule that :C rdfs:subClassOf :C).

An app can write "+" to skip the zero match "+" is '1 or more' where "*" 
is 'zero or more'

 Andy

Received on Monday, 4 January 2010 16:53:40 UTC