On 11/08/14 07:39, Wang Darrell wrote:
so I need to figure out how the bulitin work in code and built a new one
that kind of countMatch?
If you really need to do this in rules then yes.
What is that mean you said API would be eaiser than SPARQL?
Just that, given the info you have available in a builtin, it will be
easy to create a Triple pattern than you can pass to Graph.find and then
just count the number of results. You could create and run a full SPARQL
query but it's not necessary.
and should I
know about register the new builtin to somewhere ?
Yes, there's a brief mention of the details at:
https://jena.apache.org/documentation/inference/#extensions
Looking at the code for RuleMap (which defines a registers a "Deduce"
builtin) would probably help.
Dave
2014-08-08 15:14 GMT+08:00 Dave Reynolds <[email protected]>:
On 08/08/14 03:08, Wang Darrell wrote:
here is part of my ontology
- ( Stevie_Wonder - hasMusicalRole - wordnet_synthesist_110687231 )
- ( Stevie_Wonder - hasMusicalRole - wordnet_bass_guitar_102804123 )
- ( Stevie_Wonder - hasMusicalRole - wordnet_piano_103928116 )
Can I use something like
(?x :hasMusicalRole ?y)
and get a count like 3 , then produce a new fact like
( Stevie_Wonder - can - playMutipleInstrument )
while we know he can play 3 kind of instrument.
No, as I said in my last reply the rules can't count the number of times
they fire or would fire without a lot of messing with non-monotonic rules
and arithmetic.
Or is there any way to use Sparql in rules?
like
[ rule:
SELECT count(?y) WHERE { ?s yago:hasMusicalRole ?y . }
->
( Stevie_Wonder - can - playMutipleInstrument )
]
There isn't a way to do that directly at the moment. There is a Google
Summer of Code project exploring the possibility of this but it is a
separate experiment and not part of the main Jena codebase.
However, for just counting it would be pretty easy to create a rules
builtin, something like:
countMatches(?s, ?p, ?o, ?count)
which would do this. The countMatches implementation could use SPARQL but
since it only needs to count triples then just doing it using the API would
be easier. Remember to mark the builtin as non-monotonic.
Dave
