And what is the question now? By the way, those rules do not overwrite any value, the logic is supposed to be monotonic, i.e. only additional triples are inferred. Replacement has to be done in the application code.
> The students have to appear multiple time in the exam. When student appears > first time, he scored 80% and got in the category of Excellent Students > list. Second time he appears, he scored 60% and thus appeared in Average > Student. > Now after two exams, the Student in the owl file should be in the Average > Student list but both Excellent and Average Student appears and thus the > first value of first exam also there. > > On Sun, Oct 16, 2016 at 9:16 PM, Dave Reynolds <[email protected]> > wrote: > >> On 14/10/16 14:53, javed khan wrote: >> >>> I have divided Students into ExcellentStudents and AverageStudents based >>> on >>> some criteria via Jena rules: if student got 75% or more, he/she will be >>> in >>> "ExcellentStudents" else "AverageStudents". >>> In first exam, if some one takes 75% and put into ExcellentStudents but >>> next time if he scores less than 75%, he will be AverageStudents. >>> >>> The problem is that when I store it in the file, the previous value does >>> not overwrite the new one and I see both categories in the owl file like: >>> John >>> AverageStudents >>> ExcellentStudents >>> >>> How can we cope with this issue? >>> >> >> If in your data there is only ever one exam result for a given student >> then you it might make sense to have AverageStudents/ExcellentStudent >> classes. However, if you have multiple exam results in the same data then >> naturally some will be average on some and excellent on others. >> >> So you have to decide what your semantics are. Do you want >> ExcellentStudent to mean that the student averages 75% or more across all >> exams? Or you you want an n-relationship between students, exams and >> classifications? >> >> Once you've decided what you semantics are and how the answers should look >> then you can figure out an implementation. >> >> Dave >> >> >> >>> The rules are: >>> >>> String rule = "[rule1:(?x http://www.w3.org/1999/02/22-rdf-syntax-ns#type >>> http://www.semanticweb.org#Student) " >>> + "( ?x http://www.semanticweb.org#score ?marks )" >>> + "greaterThan(?marks, 70) " >>> + " -> (?x http://www.w3.org/1999/02/22-r >>> df-syntax-ns#type >>> http://www.semanticweb.org#ExcellentStudents )]" >>> >>> + "[rule2:(?x http://www.w3.org/1999/02/22-rdf-syntax-ns#type >>> http://www.semanticweb.org#Student) " >>> + "( ?x http://www.semanticweb.org#score ?marks )" >>> + "lessThan(?marks, 70) " >>> + " -> (?x http://www.w3.org/1999/02/22-r >>> df-syntax-ns#type >>> http://www.semanticweb.org#AverageStudents )]"; >>> >>> >>> for (Iterator i = inf.listResourcesWithProperty(RDF.type,stutype1 ); >>> i.hasNext();) { >>> inf.listStatements(null,RDF.type, "ExcellentStudents"); >>> >>> } >>> for (Iterator i = inf.listResourcesWithProperty(RDF.type, stutype2); >>> i.hasNext();) { >>> inf.listStatements(null,RDF.type, "AverageStudents"); >>> >>> } >>> >>> I also tried with SPARQL but same result. >>> SELECT * " + >>> " WHERE { ?x rdf:type std:ExcellentStudents . ?x >>> rdf:type >>> std:AverageStudents}"; >>> >>> -- Lorenz Bühmann AKSW group, University of Leipzig Group: http://aksw.org - semantic web research center
