Hi all,
I fixed the error Dave found, but it does not seem to activate ‘backward’ mode. I test it by providing a wrong value ‘bla’ instead of ‘backward’ and check whether Fuseki fails to load the assembler. But, unfortunately, it doesn’t fail. Any other suggestions on how to enable ‘backward’ mode from an assembler file? Regards, Barry Verzonden vanaf mijn Windows 10-telefoon Van: Dave Reynolds<mailto:[email protected]> Verzonden: donderdag 18 januari 2018 09:40 Aan: [email protected]<mailto:[email protected]> Onderwerp: Re: GenericRuleReasoner with limited scope Hi Barry, I'm not sure of the assembler syntax but there's one error in your example which might fix it: > @prefix rr: <http://jena.hpl.hp.com/2003/RuleReasoner> . That should be: @prefix rr: <http://jena.hpl.hp.com/2003/RuleReasoner#> . Dave On 17/01/18 15:12, Nouwt, B. (Barry) wrote: > Hi Dave, thanks for the answer. > > I was not aware that the backward reasoner started at triple patterns > (retrieved from the SPARQL query), so I will definitely test whether that > indeed causes the rule to be applied once instead of twice in the example > described in my second post. > > My setup uses Apache Jena Fuseki, so the PROPruleMode should be configured > via a assembly TTL file. Do you know how to do that? I found the > 'http://jena.hpl.hp.com/2003/RuleReasoner/ruleMode' property in the > ReasonerVocabulary.java file [1], but it does not seem to load this property > when I use the following assembly: > > @prefix rr: <http://jena.hpl.hp.com/2003/RuleReasoner> . > . > . > . > > <#infGraph> rdf:type ja:InfModel ; > ja:reasoner [ ja:rulesFrom <file:src/test/resources/et.rules> ; > rr:ruleMode "backward" ; ] ; > ja:content <#test-inf> . > > > Any pointers are welcome! > > Regards, Barry > > [1] > https://github.com/apache/jena/blob/cc038809fb622779933831011909714e22ef494c/jena-core/src/main/java/org/apache/jena/vocabulary/ReasonerVocabulary.java#L77 > > -----Original Message----- > From: Dave Reynolds [mailto:[email protected]] > Sent: woensdag 17 januari 2018 09:33 > To: [email protected] > Subject: Re: GenericRuleReasoner with limited scope > > On 16/01/18 09:55, Nouwt, B. (Barry) wrote: >> Hi everyone, >> >> Currently I'm using the GenericRuleReasoner of Apache Jena in my project to >> apply custom rules to my RDF data. This works as expected: as soon as I >> execute the first SPARQL query in Apache Jena Fuseki, the >> GenericRuleReasoner correctly determines all the derived triples and the >> query can be answered. >> >> Now I am looking for the following GenericRuleReasoner (or another reasoner) >> behavior: >> >> 1. I would like the GenericRuleReasoner to take the SPARQL query into >> account when reasoning. So, only reason about those facts that 'seem' >> relevant for answering the SPARQL query. >> 2. I would like the GenericRuleReasoner to remove the derived triples >> after the SPARQL query has been answered. So, the next time it receives the >> same SPARQL query, it will not be able to reuse the previous reasoning >> result. > > If I understand what you want then use the backward rather than forward > engine. > > The GenericRuleReasoner contains two engines which can be used separately or > in a cascade (hybrid mode). For configuring this see PROPruleMode in > https://jena.apache.org/documentation/inference/#RULEconfiguration > > The backward reasoner is driven by goals at the level of triple patterns and > isn't aware of the overall sparql query so the goals are not very selective > but it will at least help with point #1. > > In terms of point #2 then the backward engine, by default, will not retain > any answers. You can use the tabling declarations to cause it to selectively > remember the answer to specific (sub)goals if you need to see: > https://jena.apache.org/documentation/inference/#RULEbackward > > Note that in hybrid mode (the default) you can still use backward rules by > writing them with the arrow reversed. The advantage of switching the reasoner > mode is that you can use the same rule source syntax and run the rules in > either forward or backward mode to test the difference. > > Dave > This message may contain information that is not intended for you. If you are > not the addressee or if this message was sent to you by mistake, you are > requested to inform the sender and delete the message. TNO accepts no > liability for the content of this e-mail, for the manner in which you use it > and for damage of any kind resulting from the risks inherent to the > electronic transmission of messages. >
