Le 20 mars 2014 à 11:20, Dave Reynolds <[email protected]> a écrit :
> > On 20/03/14 09:46, Christophe FAGOT wrote: >> >> Le 19 mars 2014 à 18:46, Dave Reynolds <[email protected]> a écrit : >> >>> >>> On 19/03/14 16:46, Christophe FAGOT wrote: >>>> Hi Jena folks, >>>> >>>> since I need to use Jena with its RETEEngine, I’m actually investigating >>>> what is actually feasible / usable with this engine functionalities. >>>> >>>> I would like to develop my own BuiltIn, used in the head of a forward >>>> rule, and doing some actions when a new rule context appears (due to >>>> triples adding) for the body rule, while doing some other actions when a >>>> rule context disappears (dur to triples removal) for this body rule. >>>> >>>> It appears in the RETEConflictSet (line 180) that a BuiltIn can receive >>>> only … added RETERuleContext. Hence a BuiltIn action can only be called >>>> when a RETERuleContext is added, never when a RETERuleContext is removed. >>>> >>>> Is their a reason for that ? >>> >>> The existing head builtins expect to only be fired when a potitive >>> deduction is made. This is a legacy of the fact that the rule system was >>> designed for monotonic inference and all the remove/non-monotonic >>> processing is a hack. >> >> I don’t see the relationship between monotonic inference and remove >> prohibited. A monotonic inference only means that when adding some facts in >> the knowledge base, the previous inferred data can’t be removed, while when >> removing some facts, new facts can’t be produced. And this is exactly what >> Jena Rete engine perfectly does with « standard » triple patterns. But when >> the head is a BuiltIn, that BuiltIn does not have a single chance to act the >> same way. The BuildIn can only react to added triples. And the only >> mandatory thing for a BuiltIn is to declare is it is monotonic or not. But >> it’s behavior and the triples it adds/removes in the inference graph are >> never verified to check if it really has a (non-)monotonic behavior. But >> this is another story. > > The point is that builtins in the head are only useful if they have some side > effect. Jena indeed handles removes when the rules are monotonic. As soon as > you have side-effecting builtins then all bets are off. Even if a builtin's > effect is reversible (which I take to be the case you are interested in) it's > hard to guarantee all the necessary rules will fire in "remove" mode in the > way you expect without the rule equivalent of reference counting. Absolutely agree. Would you be open to some little modifications in the RETE classes source code, if that modifications improve the ability to extend the RETE behavior (or to correct the problem of memory consumption), while preserving the actual behavior of existing rules sets using BuiltIn (hence, receiving only added data) ? Chris. > > Dave > : : . . . . . . . . . . . . . . . . . . . . . . . : : Christophe FAGOT, PhD Responsable R&D informatique intactile DESIGN : : Création d’interfaces subtiles : : +33 (0)4 67 52 88 61 +33 (0)9 50 12 05 66 20 rue du carré du roi 34000 MONTPELLIER, France http://www.intactile.com Hugh MacLeod : "It's not what the software does, it's what the user does" Les informations contenues dans cet email et ses documents attachés sont confidentielles. Elles sont exclusivement adressées aux destinataires explicitement désignés ci-dessus et ne peuvent être divulguées sans consentement de son auteur. Si vous n'êtes pas le destinataire de cet email vous ne devez pas employer, révéler, distribuer, copier, imprimer ou transmettre le contenu de cet email et devez le détruire immédiatement.
