耶拿 RDFS 推理未返回预期结果

Question

我有以下两个三元组：

<http://example.com/a> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <http://example.com/b> . 
<http://example.com/b> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <http://example.com/c> .

以及以下 Jena 代码：

Reasoner reasoner = RDFSRuleReasonerFactory.theInstance().create(null);
    reasoner.setParameter(ReasonerVocabulary.PROPsetRDFSLevel, ReasonerVocabulary.RDFS_SIMPLE);
    reasoner.setDerivationLogging(true);

    Model schema = FileManager.get().loadModel(schemaFilepath);
    InfModel infmodel = ModelFactory.createInfModel(reasoner, schema);

    OutputStream output = new FileOutputStream(outputFilepath);
    RDFDataMgr.write(output, infmodel.getDeductionsModel(), RDFFormat.NT);

如果我理解规范正确，我应该从 getDeductionsModel() 获得：

<http://example.com/a> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <http://example.com/c> .

但是我得到的是一个空集。有什么想法吗？

Answer 1

我认为推论模型是按需填充的，这取决于特定推理者如何使用推论模型。很有可能仅在请求时生成一些推导的三元组，并且不将它们存储在推导模型中。例如，在下面的示例中，我们打印推导模型，然后是整个模型，然后再次打印推导模型，我们可以看到所需的子类三元组仅在我们打印 entire[=17 时出现=] 模型。一般来说，您应该使用顶级模型，而不是演绎模型，除非您知道关于推理器的实现以及它将使用演绎模型的内容。

import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import org.apache.jena.riot.RDFDataMgr; import org.apache.jena.riot.RDFLanguages; import com.hp.hpl.jena.ontology.OntModel; import com.hp.hpl.jena.ontology.OntModelSpec; import com.hp.hpl.jena.rdf.model.ModelFactory; public class RDFSReasoningExample { public static void main(String[] args) throws IOException { OntModel model = ModelFactory.createOntologyModel(OntModelSpec.RDFS_MEM_RDFS_INF); String content = ("" + "@prefix : <urn:ex:>.\n" + "@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>.\n" + "\n" + ":a rdfs:subClassOf :b .\n" + ":b rdfs:subClassOf :c .\n"); try ( InputStream in = new ByteArrayInputStream(content.getBytes()) ) { RDFDataMgr.read(model, in, RDFLanguages.TTL); } System.out.println("* Write the deductions model"); RDFDataMgr.write(System.out, model.getDeductionsModel(), RDFLanguages.NT); System.out.println("* Write the model"); RDFDataMgr.write(System.out, model, RDFLanguages.NT); System.out.println("* Write the deductions model again"); RDFDataMgr.write(System.out, model.getDeductionsModel(), RDFLanguages.NT); } }

* Write the deductions model …nothing about :a, :b, or :c… * Write the model … <urn:ex:a> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <urn:ex:b> . <urn:ex:b> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <urn:ex:c> . <urn:ex:c> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <urn:ex:c> . <urn:ex:a> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <urn:ex:a> . <urn:ex:a> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <urn:ex:c> . <urn:ex:b> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <urn:ex:b> . … * Write the deductions model again …nothing about :a, :b, or :c…

耶拿 RDFS 推理未返回预期结果

Jena RDFS reasoning not returning expected results

java

rdfs

jena

reasoning