I'm not sure I completely understood your answer. Please confirm my interpretation.
I think I have understood, that the solution is to write rule-based materialization that substitute the reasoners. Apparently since TDB it is possible to execute those rules of inferences on my big ontology, is it? It seems that rule-based materialization is not applicable to OWL2 ontologies (which do not fit into any of the profiles), is it? Greetings and thank you very much for your time. ----- Mensaje original ----- De: "Lorenz B." <buehm...@informatik.uni-leipzig.de> Para: users@jena.apache.org Enviados: Lunes, 20 de Marzo 2017 2:24:33 Asunto: Re: [MASSMAIL]Re: about TDB JENA It totally depends on the reasoning that you want to apply. OWL 2 DL is not possible via simple rules, but for instance RDFS/OLW Horst and OWL RL can be doen via rule-based materialization. > I keep going into details, thank you for responding. > > Of the 13 million property assertions, almost 80% are assertions of object > properties, ie relationships between individuals. In the last ontology I > generated automatically, only for one of the municipalities in Cuba, I had 27 > 763 887 of object properties assertions, 105 054 data property assertions and > 8 158 individuals. > > The inference I need is basically the following: > > 1) To know all the individuals that belong to a class directly and > indirectly, taking into consideration the equivalence between classes and > between individuals. Depends on the reasoning profile and the ontology schema, but might be covered by SPARQL 1.1 as long as you need only RDFS/OWL RL reasoning. > > 2) Given an individual (Ind) and an object property (OP), know all > individuals related to "Ind", through OP. Considering the following > characteristics of OP: symmetry, functional, transitivity, inverse, > equivalence. > > 3) Search the direct and indirect subclasses of a class. SPARQL 1.1 property paths as long as the classes are atomic classes and not complex class expressions. > > 4) Identify all classes equivalent to a class, considering that the > equivalence relation is transitive. > > 5) Identify the set of superclasses of a class. SPARQL 1.1 property paths as long as the classes are atomic classes and not complex class expressions. > > Could JENA and TDB afford that kind of inference on my big ontologies? > > Excuse me, but I'm not a deep connoisseur of the SPARQL language. I have only > used it to access data that is explicit on the ontology, similar to SQL in > relational databases, I have never used it (nor do I know if it is possible > to do so) to infer implicit knowledge. The approach that people do is either query rewriting w.r.t. the schema or forward-chaining, i.e. materialization based on a set of inference rules. For RDFS, OWL Horst and OWL RL this is possible. Materialization has to be done only once (given that the dataset does not change). > > I put copy to Ignazio Palmisano, an excellent researcher and connoisseur of > the framework OWLAPI. With which I have been exchanging on this subject. > > Best regards. > > > ----- Mensaje original ----- > De: "Dave Reynolds" <dave.e.reyno...@gmail.com> > Para: users@jena.apache.org > Enviados: Domingo, 19 de Marzo 2017 13:45:48 > Asunto: Re: [MASSMAIL]Re: about TDB JENA > > On 19/03/17 15:52, Manuel Enrique Puebla Martinez wrote: >> I consider that I did not know how to explain correctly in my previous >> email, I repeat the two questions: >> >> >> 1) I read the page https://jena.apache.org/documentation/tdb/assembler.html, >> I do not think it is what I need. >> >> I work with large OWL2 ontologies from the OWLAPI framework, generated >> automatically. With thousands of individuals and more than 13 million >> property assertions (data and objects). As one may assume, one of the >> limitations I have is that OWLAPI itself can not manage these large >> ontologies, that is, because OWLAPI loads the whole owl file into RAM. Not >> to dream that some classical reasoner (Pellet, Hermit, etc.) can infer new >> knowledge about these great ontologies. >> >> Once explained the problem I have, comes the question: Does JENA solve this >> test ?, ie with JENA and TDB I can generate my great ontologies in OWL2 ?, >> With JENA and TDB I can use a reasoner to infer new implicit knowledge >> (unstated) on my big ontologies? >> >> I do not think JENA will be able to solve this problem, it would be a >> pleasant surprise for me. Unfortunately so far I had not read about TDB and >> the potentialities of JENA in external memory. > Indeed Jena does not offer fully scalable reasoning, all inference is > done in memory. > > That said 13 million assertions is not *that* enormous, the cost of > inference depends on the complexity of the ontology as much its scale. > So 13m triples with some simple domain/range inferences might work in > memory. > > TDB storage itself scales just fine and querying does not load all the > data into memory. So if you don't actually need inference, or only need > simple inference that can be usefully expressed as part of the SPARQL > query then you are fine. > > Dave > > La @universidad_uci es Fidel. Los jóvenes no fallaremos. > #HastaSiempreComandante > #HastalaVictoriaSiempre > -- Lorenz Bühmann AKSW group, University of Leipzig Group: http://aksw.org - semantic web research center La @universidad_uci es Fidel. Los jóvenes no fallaremos. #HastaSiempreComandante #HastalaVictoriaSiempre
